esqueleto-3.3.3.2: Type-safe EDSL for SQL queries on persistent backends.

Safe Haskell | None
Language | Haskell2010

Database.Esqueleto.Internal.Language

Contents

- The pretty face
- The guts

Description

This is an internal module, anything exported by this module may change without a major version bump. Please use only Database.Esqueleto if possible.

Synopsis

- from :: From a => (a -> SqlQuery b) -> SqlQuery b
- newtype Value a = Value {
  - unValue :: a
  }
- newtype ValueList a = ValueList a
- data SomeValue where
  - SomeValue :: SqlExpr (Value a) -> SomeValue
- class ToSomeValues a where
  - toSomeValues :: a -> [SomeValue]
- data InnerJoin a b = a `InnerJoin` b
- data CrossJoin a b = a `CrossJoin` b
- data LeftOuterJoin a b = a `LeftOuterJoin` b
- data RightOuterJoin a b = a `RightOuterJoin` b
- data FullOuterJoin a b = a `FullOuterJoin` b
- data OnClauseWithoutMatchingJoinException = OnClauseWithoutMatchingJoinException String
- data OrderBy
- data DistinctOn
- data Update typ
- data Insertion a
- data LockingKind
  - = ForUpdate
  - | ForUpdateSkipLocked
  - | ForShare
  - | LockInShareMode
- class PersistField a => SqlString a
- class ToBaseId ent where
  - type BaseEnt ent :: *
  - toBaseIdWitness :: Key (BaseEnt ent) -> Key ent
- data JoinKind
  - = InnerJoinKind
  - | CrossJoinKind
  - | LeftOuterJoinKind
  - | RightOuterJoinKind
  - | FullOuterJoinKind
- class IsJoinKind join where
  - smartJoin :: a -> b -> join a b
  - reifyJoinKind :: join a b -> JoinKind
- class BackendCompatible sup sub where
  - projectBackend :: sub -> sup
- data PreprocessedFrom a
- class From a
- class FromPreprocess a
- when_ :: expr (Value Bool) -> () -> expr a -> (expr (Value Bool), expr a)
- then_ :: ()
- else_ :: expr a -> expr a
- where_ :: SqlExpr (Value Bool) -> SqlQuery ()
- on :: SqlExpr (Value Bool) -> SqlQuery ()
- groupBy :: ToSomeValues a => a -> SqlQuery ()
- orderBy :: [SqlExpr OrderBy] -> SqlQuery ()
- rand :: SqlExpr OrderBy
- asc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy
- desc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy
- limit :: Int64 -> SqlQuery ()
- offset :: Int64 -> SqlQuery ()
- distinct :: SqlQuery a -> SqlQuery a
- distinctOn :: [SqlExpr DistinctOn] -> SqlQuery a -> SqlQuery a
- don :: SqlExpr (Value a) -> SqlExpr DistinctOn
- distinctOnOrderBy :: [SqlExpr OrderBy] -> SqlQuery a -> SqlQuery a
- having :: SqlExpr (Value Bool) -> SqlQuery ()
- locking :: LockingKind -> SqlQuery ()
- sub_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)
- (^.) :: forall typ val. (PersistEntity val, PersistField typ) => SqlExpr (Entity val) -> EntityField val typ -> SqlExpr (Value typ)
- (?.) :: (PersistEntity val, PersistField typ) => SqlExpr (Maybe (Entity val)) -> EntityField val typ -> SqlExpr (Value (Maybe typ))
- val :: PersistField typ => typ -> SqlExpr (Value typ)
- isNothing :: PersistField typ => SqlExpr (Value (Maybe typ)) -> SqlExpr (Value Bool)
- just :: SqlExpr (Value typ) -> SqlExpr (Value (Maybe typ))
- nothing :: SqlExpr (Value (Maybe typ))
- joinV :: SqlExpr (Value (Maybe (Maybe typ))) -> SqlExpr (Value (Maybe typ))
- withNonNull :: PersistField typ => SqlExpr (Value (Maybe typ)) -> (SqlExpr (Value typ) -> SqlQuery a) -> SqlQuery a
- countRows :: Num a => SqlExpr (Value a)
- count :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a)
- countDistinct :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a)
- not_ :: SqlExpr (Value Bool) -> SqlExpr (Value Bool)
- (==.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (>=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (>.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (<=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (<.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (!=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
- (&&.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
- (||.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
- between :: PersistField a => SqlExpr (Value a) -> (SqlExpr (Value a), SqlExpr (Value a)) -> SqlExpr (Value Bool)
- (+.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- (-.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- (/.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- (*.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
- random_ :: (PersistField a, Num a) => SqlExpr (Value a)
- round_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- ceiling_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- floor_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- min_ :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value (Maybe a))
- max_ :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value (Maybe a))
- sum_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b))
- avg_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b))
- castNum :: (Num a, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
- castNumM :: (Num a, Num b) => SqlExpr (Value (Maybe a)) -> SqlExpr (Value (Maybe b))
- coalesce :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value (Maybe a))
- coalesceDefault :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
- lower_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
- upper_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
- trim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
- ltrim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
- rtrim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
- length_ :: (SqlString s, Num a) => SqlExpr (Value s) -> SqlExpr (Value a)
- left_ :: (SqlString s, Num a) => (SqlExpr (Value s), SqlExpr (Value a)) -> SqlExpr (Value s)
- right_ :: (SqlString s, Num a) => (SqlExpr (Value s), SqlExpr (Value a)) -> SqlExpr (Value s)
- like :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool)
- ilike :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool)
- (%) :: SqlString s => SqlExpr (Value s)
- concat_ :: SqlString s => [SqlExpr (Value s)] -> SqlExpr (Value s)
- (++.) :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value s)
- castString :: (SqlString s, SqlString r) => SqlExpr (Value s) -> SqlExpr (Value r)
- subList_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a)
- valList :: PersistField typ => [typ] -> SqlExpr (ValueList typ)
- justList :: SqlExpr (ValueList typ) -> SqlExpr (ValueList (Maybe typ))
- in_ :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool)
- notIn :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool)
- exists :: SqlQuery () -> SqlExpr (Value Bool)
- notExists :: SqlQuery () -> SqlExpr (Value Bool)
- set :: PersistEntity val => SqlExpr (Entity val) -> [SqlExpr (Update val)] -> SqlQuery ()
- (=.) :: (PersistEntity val, PersistField typ) => EntityField val typ -> SqlExpr (Value typ) -> SqlExpr (Update val)
- (+=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- (-=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- (*=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- (/=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
- case_ :: PersistField a => [(SqlExpr (Value Bool), SqlExpr (Value a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
- toBaseId :: ToBaseId ent => SqlExpr (Value (Key ent)) -> SqlExpr (Value (Key (BaseEnt ent)))
- (<#) :: (a -> b) -> SqlExpr (Value a) -> SqlExpr (Insertion b)
- (<&>) :: SqlExpr (Insertion (a -> b)) -> SqlExpr (Value a) -> SqlExpr (Insertion b)
- subSelect :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value (Maybe a))
- subSelectMaybe :: PersistField a => SqlQuery (SqlExpr (Value (Maybe a))) -> SqlExpr (Value (Maybe a))
- subSelectCount :: (Num a, PersistField a) => SqlQuery ignored -> SqlExpr (Value a)
- subSelectList :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a)
- subSelectForeign :: (BackendCompatible SqlBackend (PersistEntityBackend val1), PersistEntity val1, PersistEntity val2, PersistField a) => SqlExpr (Entity val2) -> EntityField val2 (Key val1) -> (SqlExpr (Entity val1) -> SqlExpr (Value a)) -> SqlExpr (Value a)
- subSelectUnsafe :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)

# The pretty face

from :: From a => (a -> SqlQuery b) -> SqlQuery b Source #

`FROM` clause: bring entities into scope.

This function internally uses two type classes in order to provide some flexibility of how you may call it. Internally we refer to these type classes as the two different magics.

The innermost magic allows you to use `from` with the following types:

- `expr (Entity val)`, which brings a single entity into scope.
- `expr (Maybe (Entity val))`, which brings a single entity that may be `NULL` into scope. Used for `OUTER JOIN`s.
- A `JOIN` of any other two types allowed by the innermost magic, where a `JOIN` may be an `InnerJoin`, a `CrossJoin`, a `LeftOuterJoin`, a `RightOuterJoin`, or a `FullOuterJoin`. The `JOINs` have left fixity.

The outermost magic allows you to use `from` on any tuples of types supported by innermost magic (and also tuples of tuples, and so on), up to 8-tuples.

Note that using `from` for the same entity twice does work and corresponds to a self-join. You don't even need to use two different calls to `from`, you may use a `JOIN` or a tuple.

The following are valid examples of uses of `from` (the types of the arguments of the lambda are inside square brackets):

    from $ \person -> ...
    from $ \(person, blogPost) -> ...
    from $ \(p `LeftOuterJoin` mb) -> ...
    from $ \(p1 `InnerJoin` f `InnerJoin` p2) -> ...
    from $ \((p1 `InnerJoin` f) `InnerJoin` p2) -> ...

The types of the arguments to the lambdas above are, respectively:

    person
      :: ( Esqueleto query expr backend
         , PersistEntity Person
         , PersistEntityBackend Person ~ backend
         ) => expr (Entity Person)
    (person, blogPost)
      :: (...) => (expr (Entity Person), expr (Entity BlogPost))
    (p `LeftOuterJoin` mb)
      :: (...) => InnerJoin (expr (Entity Person)) (expr (Maybe (Entity BlogPost)))
    (p1 `InnerJoin` f `InnerJoin` p2)
      :: (...) => InnerJoin
                    (InnerJoin (expr (Entity Person))
                               (expr (Entity Follow)))
                    (expr (Entity Person))
    (p1 `InnerJoin` (f `InnerJoin` p2)) ::
      :: (...) => InnerJoin
                    (expr (Entity Person))
                    (InnerJoin (expr (Entity Follow))
                               (expr (Entity Person)))

Note that some backends may not support all kinds of `JOIN`s.

newtype Value a Source #

A single value (as opposed to a whole entity). You may use `(`^.`)` or `(`?.`)` to get a `Value` from an `Entity`.

Constructors

Value |

Fields

- unValue :: a

#### Instances

Instances details

Monad Value Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods (>>=) :: Value a -> (a -> Value b) -> Value b (>>) :: Value a -> Value b -> Value b return :: a -> Value a
Functor Value Source # | Since: 1.4.4
Instance details Defined in Database.Esqueleto.Internal.Internal Methods fmap :: (a -> b) -> Value a -> Value b (<$) :: a -> Value b -> Value a
Applicative Value Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods pure :: a -> Value a (<*>) :: Value (a -> b) -> Value a -> Value b liftA2 :: (a -> b -> c) -> Value a -> Value b -> Value c (*>) :: Value a -> Value b -> Value b (<*) :: Value a -> Value b -> Value a
Eq a => Eq (Value a) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods (==) :: Value a -> Value a -> Bool (/=) :: Value a -> Value a -> Bool
Ord a => Ord (Value a) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods compare :: Value a -> Value a -> Ordering (<) :: Value a -> Value a -> Bool (<=) :: Value a -> Value a -> Bool (>) :: Value a -> Value a -> Bool (>=) :: Value a -> Value a -> Bool max :: Value a -> Value a -> Value a min :: Value a -> Value a -> Value a
Show a => Show (Value a) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods showsPrec :: Int -> Value a -> ShowS show :: Value a -> String showList :: [Value a] -> ShowS
ToSomeValues (SqlExpr (Value a)) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: SqlExpr (Value a) -> [SomeValue] Source #
ToAliasReference (SqlExpr (Value a)) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toAliasReference :: Ident -> SqlExpr (Value a) -> SqlQuery (ToAliasReferenceT (SqlExpr (Value a))) Source #
ToAlias (SqlExpr (Value a)) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toAlias :: SqlExpr (Value a) -> SqlQuery (ToAliasT (SqlExpr (Value a))) Source #
ToMaybe (SqlExpr (Value a)) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toMaybe :: SqlExpr (Value a) -> ToMaybeT (SqlExpr (Value a)) Source #
PersistField a => SqlSelect (SqlExpr (Value a)) (Value a) Source # | You may return any single value (i.e. a single column) from a `select` query.
Instance details Defined in Database.Esqueleto.Internal.Internal Methods sqlSelectCols :: IdentInfo -> SqlExpr (Value a) -> (Builder, [PersistValue]) Source # sqlSelectColCount :: Proxy (SqlExpr (Value a)) -> Int Source # sqlSelectProcessRow :: [PersistValue] -> Either Text (Value a) Source # sqlInsertInto :: IdentInfo -> SqlExpr (Value a) -> (Builder, [PersistValue]) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe a', ma ~ ToMaybeT a', ToMaybe b', mb ~ ToMaybeT b') => ToFrom (FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool)) -> From (ToFromT (FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool)))) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe a', ma ~ ToMaybeT a') => ToFrom (RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool)) -> From (ToFromT (RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool)))) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe b', mb ~ ToMaybeT b') => ToFrom (LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool)) -> From (ToFromT (LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool)))) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b') => ToFrom (InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool)) -> From (ToFromT (InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool)))) Source #

newtype ValueList a Source #

A list of single values. There's a limited set of functions able to work with this data type (such as `subList_select`, `valList`, `in_` and `exists`).

Constructors

ValueList a |

#### Instances

Instances details

Eq a => Eq (ValueList a) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods (==) :: ValueList a -> ValueList a -> Bool (/=) :: ValueList a -> ValueList a -> Bool
Ord a => Ord (ValueList a) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods compare :: ValueList a -> ValueList a -> Ordering (<) :: ValueList a -> ValueList a -> Bool (<=) :: ValueList a -> ValueList a -> Bool (>) :: ValueList a -> ValueList a -> Bool (>=) :: ValueList a -> ValueList a -> Bool max :: ValueList a -> ValueList a -> ValueList a min :: ValueList a -> ValueList a -> ValueList a
Show a => Show (ValueList a) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods showsPrec :: Int -> ValueList a -> ShowS show :: ValueList a -> String showList :: [ValueList a] -> ShowS

data SomeValue where Source #

A wrapper type for for any `expr (Value a)` for all a.

Constructors

SomeValue :: SqlExpr (Value a) -> SomeValue |

class ToSomeValues a where Source #

A class of things that can be converted into a list of SomeValue. It has instances for tuples and is the reason why `groupBy` can take tuples, like ``groupBy` (foo `^.` FooId, foo `^.` FooName, foo `^.` FooType)`.

Methods

toSomeValues :: a -> [SomeValue] Source #

#### Instances

Instances details

ToSomeValues (SqlExpr (Value a)) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: SqlExpr (Value a) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b) => ToSomeValues (a, b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b, ToSomeValues c) => ToSomeValues (a, b, c) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b, c) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b, ToSomeValues c, ToSomeValues d) => ToSomeValues (a, b, c, d) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b, c, d) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b, ToSomeValues c, ToSomeValues d, ToSomeValues e) => ToSomeValues (a, b, c, d, e) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b, c, d, e) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b, ToSomeValues c, ToSomeValues d, ToSomeValues e, ToSomeValues f) => ToSomeValues (a, b, c, d, e, f) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b, c, d, e, f) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b, ToSomeValues c, ToSomeValues d, ToSomeValues e, ToSomeValues f, ToSomeValues g) => ToSomeValues (a, b, c, d, e, f, g) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b, c, d, e, f, g) -> [SomeValue] Source #
(ToSomeValues a, ToSomeValues b, ToSomeValues c, ToSomeValues d, ToSomeValues e, ToSomeValues f, ToSomeValues g, ToSomeValues h) => ToSomeValues (a, b, c, d, e, f, g, h) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toSomeValues :: (a, b, c, d, e, f, g, h) -> [SomeValue] Source #

data InnerJoin a b infixl 2 Source #

Data type that represents an `INNER JOIN` (see `LeftOuterJoin` for an example).

Constructors

a `InnerJoin` b infixl 2 |

#### Instances

Instances details

IsJoinKind InnerJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> InnerJoin a b Source # reifyJoinKind :: InnerJoin a b -> JoinKind Source #
FromPreprocess (InnerJoin a b) => From (InnerJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (InnerJoin a b) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b') => ToFrom (InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool)) -> From (ToFromT (InnerJoin a (b, (a' :& b') -> SqlExpr (Value Bool)))) Source #
ToFrom (InnerJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: InnerJoin a b -> From (ToFromT (InnerJoin a b)) Source #

data CrossJoin a b infixl 2 Source #

Data type that represents a `CROSS JOIN` (see `LeftOuterJoin` for an example).

Constructors

a `CrossJoin` b infixl 2 |

#### Instances

Instances details

IsJoinKind CrossJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> CrossJoin a b Source # reifyJoinKind :: CrossJoin a b -> JoinKind Source #
FromPreprocess (CrossJoin a b) => From (CrossJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (CrossJoin a b) Source #
(ToFrom a, ToFrom b) => ToFrom (CrossJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: CrossJoin a b -> From (ToFromT (CrossJoin a b)) Source #

data LeftOuterJoin a b infixl 2 Source #

Data type that represents a `LEFT OUTER JOIN`. For example,

    select $
    from $ \(person `LeftOuterJoin` pet) ->
      ...

is translated into

    SELECT ...
    FROM Person LEFT OUTER JOIN Pet
    ...

See also: `from`.

Constructors

a `LeftOuterJoin` b infixl 2 |

#### Instances

Instances details

IsJoinKind LeftOuterJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> LeftOuterJoin a b Source # reifyJoinKind :: LeftOuterJoin a b -> JoinKind Source #
FromPreprocess (LeftOuterJoin a b) => From (LeftOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (LeftOuterJoin a b) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe b', mb ~ ToMaybeT b') => ToFrom (LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool)) -> From (ToFromT (LeftOuterJoin a (b, (a' :& mb) -> SqlExpr (Value Bool)))) Source #
ToFrom (LeftOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: LeftOuterJoin a b -> From (ToFromT (LeftOuterJoin a b)) Source #

data RightOuterJoin a b infixl 2 Source #

Data type that represents a `RIGHT OUTER JOIN` (see `LeftOuterJoin` for an example).

Constructors

a `RightOuterJoin` b infixl 2 |

#### Instances

Instances details

IsJoinKind RightOuterJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> RightOuterJoin a b Source # reifyJoinKind :: RightOuterJoin a b -> JoinKind Source #
FromPreprocess (RightOuterJoin a b) => From (RightOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (RightOuterJoin a b) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe a', ma ~ ToMaybeT a') => ToFrom (RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool)) -> From (ToFromT (RightOuterJoin a (b, (ma :& b') -> SqlExpr (Value Bool)))) Source #
ToFrom (RightOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: RightOuterJoin a b -> From (ToFromT (RightOuterJoin a b)) Source #

data FullOuterJoin a b infixl 2 Source #

Data type that represents a `FULL OUTER JOIN` (see `LeftOuterJoin` for an example).

Constructors

a `FullOuterJoin` b infixl 2 |

#### Instances

Instances details

IsJoinKind FullOuterJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> FullOuterJoin a b Source # reifyJoinKind :: FullOuterJoin a b -> JoinKind Source #
FromPreprocess (FullOuterJoin a b) => From (FullOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (FullOuterJoin a b) Source #
(ToFrom a, ToFromT a ~ a', ToFrom b, ToFromT b ~ b', ToMaybe a', ma ~ ToMaybeT a', ToMaybe b', mb ~ ToMaybeT b') => ToFrom (FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool))) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool)) -> From (ToFromT (FullOuterJoin a (b, (ma :& mb) -> SqlExpr (Value Bool)))) Source #
ToFrom (FullOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Experimental Methods toFrom :: FullOuterJoin a b -> From (ToFromT (FullOuterJoin a b)) Source #

data OnClauseWithoutMatchingJoinException Source #

Exception thrown whenever `on` is used to create an `ON` clause but no matching `JOIN` is found.

Constructors

OnClauseWithoutMatchingJoinException String |

#### Instances

Instances details

Eq OnClauseWithoutMatchingJoinException Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods (==) :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Bool (/=) :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Bool
Ord OnClauseWithoutMatchingJoinException Source # |

Instance details

Defined in Database.Esqueleto.Internal.Internal

Methods

compare :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Ordering

(<) :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Bool

(<=) :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Bool

(>) :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Bool

(>=) :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> Bool

max :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException

min :: OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException -> OnClauseWithoutMatchingJoinException

Show OnClauseWithoutMatchingJoinException Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods showsPrec :: Int -> OnClauseWithoutMatchingJoinException -> ShowS show :: OnClauseWithoutMatchingJoinException -> String showList :: [OnClauseWithoutMatchingJoinException] -> ShowS
Exception OnClauseWithoutMatchingJoinException Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods toException :: OnClauseWithoutMatchingJoinException -> SomeException # fromException :: SomeException -> Maybe OnClauseWithoutMatchingJoinException # displayException :: OnClauseWithoutMatchingJoinException -> String #

data OrderBy Source #

Phantom type used by `orderBy`, `asc` and `desc`.

data DistinctOn Source #

Phantom type used by `distinctOn` and `don`.

data Update typ Source #

Phantom type for a `SET` operation on an entity of the given type (see `set` and `(=.)`).

data Insertion a Source #

Phantom type used by `insertSelect`.

data LockingKind Source #

Different kinds of locking clauses supported by `locking`.

Note that each RDBMS has different locking support. The constructors of this datatype specify only the syntax of the locking mechanism, not its semantics. For example, even though both MySQL and PostgreSQL support `ForUpdate`, there are no guarantees that they will behave the same.

Since: 2.2.7

Constructors

ForUpdate | `FOR UPDATE` syntax. Supported by MySQL, Oracle and PostgreSQL. Since: 2.2.7
ForUpdateSkipLocked | `FOR UPDATE SKIP LOCKED` syntax. Supported by MySQL, Oracle and PostgreSQL. Since: 2.2.7
ForShare | `FOR SHARE` syntax. Supported by PostgreSQL. Since: 2.2.7
LockInShareMode | `LOCK IN SHARE MODE` syntax. Supported by MySQL. Since: 2.2.7

class PersistField a => SqlString a Source #

Phantom class of data types that are treated as strings by the RDBMS. It has no methods because it's only used to avoid type errors such as trying to concatenate integers.

If you have a custom data type or `newtype`, feel free to make it an instance of this class.

Since: 2.4.0

#### Instances

Instances details

SqlString ByteString Source # | Since: 2.3.0
Instance details Defined in Database.Esqueleto.Internal.Internal
SqlString Text Source # | Since: 2.3.0
Instance details Defined in Database.Esqueleto.Internal.Internal
SqlString Text Source # | Since: 2.3.0
Instance details Defined in Database.Esqueleto.Internal.Internal
SqlString Html Source # | Since: 2.3.0
Instance details Defined in Database.Esqueleto.Internal.Internal
a ~ Char => SqlString [a] Source # | Since: 2.3.0
Instance details Defined in Database.Esqueleto.Internal.Internal
SqlString a => SqlString (Maybe a) Source # | Since: 2.4.0
Instance details Defined in Database.Esqueleto.Internal.Internal

class ToBaseId ent where Source #

Class that enables one to use `toBaseId` to convert an entity's key on a query into another (cf. `toBaseId`).

Associated Types

type BaseEnt ent :: * Source #

e.g. `type BaseEnt MyBase = MyChild`

Methods

toBaseIdWitness :: Key (BaseEnt ent) -> Key ent Source #

Convert from the key of the BaseEnt(ity) to the key of the child entity. This function is not actually called, but that it typechecks proves this operation is safe.

# The guts

data JoinKind Source #

(Internal) A kind of `JOIN`.

Constructors

InnerJoinKind

    INNER JOIN

CrossJoinKind

    CROSS JOIN

LeftOuterJoinKind

    LEFT OUTER JOIN

RightOuterJoinKind

    RIGHT OUTER JOIN

FullOuterJoinKind

    FULL OUTER JOIN

#### Instances

Instances details

Eq JoinKind Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods (==) :: JoinKind -> JoinKind -> Bool (/=) :: JoinKind -> JoinKind -> Bool
Show JoinKind Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods showsPrec :: Int -> JoinKind -> ShowS show :: JoinKind -> String showList :: [JoinKind] -> ShowS

class IsJoinKind join where Source #

(Internal) Functions that operate on types (that should be) of kind `JoinKind`.

Methods

smartJoin :: a -> b -> join a b Source #

(Internal) `smartJoin a b` is a `JOIN` of the correct kind.

reifyJoinKind :: join a b -> JoinKind Source #

(Internal) Reify a `JoinKind` from a `JOIN`. This function is non-strict.

#### Instances

Instances details

IsJoinKind FullOuterJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> FullOuterJoin a b Source # reifyJoinKind :: FullOuterJoin a b -> JoinKind Source #
IsJoinKind RightOuterJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> RightOuterJoin a b Source # reifyJoinKind :: RightOuterJoin a b -> JoinKind Source #
IsJoinKind LeftOuterJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> LeftOuterJoin a b Source # reifyJoinKind :: LeftOuterJoin a b -> JoinKind Source #
IsJoinKind CrossJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> CrossJoin a b Source # reifyJoinKind :: CrossJoin a b -> JoinKind Source #
IsJoinKind InnerJoin Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods smartJoin :: a -> b -> InnerJoin a b Source # reifyJoinKind :: InnerJoin a b -> JoinKind Source #

class BackendCompatible sup sub where Source #

This class witnesses that two backend are compatible, and that you can convert from the `sub` backend into the `sup` backend. This is similar to the `HasPersistBackend` and `IsPersistBackend` classes, but where you don't want to fix the type associated with the `PersistEntityBackend` of a record.

Generally speaking, where you might have:

    foo ::
      ( PersistEntity record
      , PeristEntityBackend record ~ BaseBackend backend
      , IsSqlBackend backend
      )

this can be replaced with:

    foo ::
      ( PersistEntity record,
      , PersistEntityBackend record ~ backend
      , BackendCompatible SqlBackend backend
      )

This works for `SqlReadBackend` because of the `instance `BackendCompatible` `SqlBackend` `SqlReadBackend``, without needing to go through the `BaseBackend` type family.

Likewise, functions that are currently hardcoded to use `SqlBackend` can be generalized:

    -- before:
    asdf :: ReaderT SqlBackend m ()
    asdf = pure ()

    -- after:
    asdf' :: BackendCompatible SqlBackend backend => ReaderT backend m ()
    asdf' = withReaderT projectBackend asdf

Since: persistent-2.7.1

Methods

projectBackend :: sub -> sup Source #

data PreprocessedFrom a Source #

(Internal) Phantom type used to process `from` (see `fromStart`).

class From a Source #

(Internal) Class that implements the tuple `from` magic (see `fromStart`).

Minimal complete definition

from_

#### Instances

Instances details

FromPreprocess (SqlExpr (Maybe (Entity val))) => From (SqlExpr (Maybe (Entity val))) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (SqlExpr (Maybe (Entity val))) Source #
FromPreprocess (SqlExpr (Entity val)) => From (SqlExpr (Entity val)) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (SqlExpr (Entity val)) Source #
(From a, From b) => From (a, b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b) Source #
FromPreprocess (FullOuterJoin a b) => From (FullOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (FullOuterJoin a b) Source #
FromPreprocess (RightOuterJoin a b) => From (RightOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (RightOuterJoin a b) Source #
FromPreprocess (LeftOuterJoin a b) => From (LeftOuterJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (LeftOuterJoin a b) Source #
FromPreprocess (CrossJoin a b) => From (CrossJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (CrossJoin a b) Source #
FromPreprocess (InnerJoin a b) => From (InnerJoin a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (InnerJoin a b) Source #
(From a, From b, From c) => From (a, b, c) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b, c) Source #
(From a, From b, From c, From d) => From (a, b, c, d) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b, c, d) Source #
(From a, From b, From c, From d, From e) => From (a, b, c, d, e) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b, c, d, e) Source #
(From a, From b, From c, From d, From e, From f) => From (a, b, c, d, e, f) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b, c, d, e, f) Source #
(From a, From b, From c, From d, From e, From f, From g) => From (a, b, c, d, e, f, g) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b, c, d, e, f, g) Source #
(From a, From b, From c, From d, From e, From f, From g, From h) => From (a, b, c, d, e, f, g, h) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods from_ :: SqlQuery (a, b, c, d, e, f, g, h) Source #

class FromPreprocess a Source #

(Internal) Class that implements the `JOIN` `from` magic (see `fromStart`).

Minimal complete definition

fromPreprocess

#### Instances

Instances details

(PersistEntity val, BackendCompatible SqlBackend (PersistEntityBackend val)) => FromPreprocess (SqlExpr (Maybe (Entity val))) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Maybe (Entity val))))) Source #
(PersistEntity val, BackendCompatible SqlBackend (PersistEntityBackend val)) => FromPreprocess (SqlExpr (Entity val)) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Entity val)))) Source #
(FromPreprocess a, FromPreprocess b, IsJoinKind join) => FromPreprocess (join a b) Source # |
Instance details Defined in Database.Esqueleto.Internal.Internal Methods fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom (join a b))) Source #

when_ :: expr (Value Bool) -> () -> expr a -> (expr (Value Bool), expr a) Source #

Syntax sugar for `case_`.

Since: 2.1.2

then_ :: () Source #

Syntax sugar for `case_`.

Since: 2.1.2

else_ :: expr a -> expr a Source #

Syntax sugar for `case_`.

Since: 2.1.2

where_ :: SqlExpr (Value Bool) -> SqlQuery () Source #

`WHERE` clause: restrict the query's result.

on :: SqlExpr (Value Bool) -> SqlQuery () Source #

An `ON` clause, useful to describe how two tables are related. Cross joins and tuple-joins do not need an `on` clause, but `InnerJoin` and the various outer joins do.

If you don't include an `on` clause (or include too many!) then a runtime exception will be thrown.

As an example, consider this simple join:

    select $
    from $ \(foo `InnerJoin` bar) -> do
      on (foo ^. FooId ==. bar ^. BarFooId)
      ...

We need to specify the clause for joining the two columns together. If we had this:

    select $
    from $ \(foo `CrossJoin` bar) -> do
      ...

Then we can safely omit the `on` clause, because the cross join will make pairs of all records possible.

You can do multiple `on` clauses in a query. This query joins three tables, and has two `on` clauses:

    select $
    from $ \(foo `InnerJoin` bar `InnerJoin` baz) -> do
      on (baz ^. BazId ==. bar ^. BarBazId)
      on (foo ^. FooId ==. bar ^. BarFooId)
      ...

Old versions of esqueleto required that you provide the `on` clauses in reverse order. This restriction has been lifted - you can now provide `on` clauses in any order, and the SQL should work itself out. The above query is now totally equivalent to this:

    select $
    from $ \(foo `InnerJoin` bar `InnerJoin` baz) -> do
      on (foo ^. FooId ==. bar ^. BarFooId)
      on (baz ^. BazId ==. bar ^. BarBazId)
      ...

groupBy :: ToSomeValues a => a -> SqlQuery () Source #

`GROUP BY` clause. You can enclose multiple columns in a tuple.

    select $ from \(foo `InnerJoin` bar) -> do
      on (foo ^. FooBarId ==. bar ^. BarId)
      groupBy (bar ^. BarId, bar ^. BarName)
      return (bar ^. BarId, bar ^. BarName, countRows)

With groupBy you can sort by aggregate functions, like so (we used `let` to restrict the more general `countRows` to `SqlSqlExpr (Value Int)` to avoid ambiguity---the second use of `countRows` has its type restricted by the `:: Int` below):

    r <- select $ from \(foo `InnerJoin` bar) -> do
      on (foo ^. FooBarId ==. bar ^. BarId)
      groupBy $ bar ^. BarName
      let countRows' = countRows
      orderBy [asc countRows']
      return (bar ^. BarName, countRows')
    forM_ r $ \(Value name, Value count) -> do
      print name
      print (count :: Int)

### Need more columns?

The `ToSomeValues` class is defined for `SqlExpr` and tuples of `SqlExpr`s. We only have definitions for up to 8 elements in a tuple right now, so it's possible that you may need to have more than 8 elements.

For example, consider a query with a `groupBy` call like this:

    groupBy (e0, e1, e2, e3, e4, e5, e6, e7)

This is the biggest you can get with a single tuple. However, you can easily nest the tuples to add more:

    groupBy ((e0, e1, e2, e3, e4, e5, e6, e7), e8, e9)

orderBy :: [SqlExpr OrderBy] -> SqlQuery () Source #

`ORDER BY` clause. See also `asc` and `desc`.

Multiple calls to `orderBy` get concatenated on the final query, including `distinctOnOrderBy`.

rand :: SqlExpr OrderBy Source #

Deprecated: Since 2.6.0: `rand` ordering function is not uniform across all databases! To avoid accidental partiality it will be removed in the next major version.

`ORDER BY random()` clause.

Since: 1.3.10

asc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy Source #

Ascending order of this field or SqlExpression.

desc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy Source #

Descending order of this field or SqlExpression.

limit :: Int64 -> SqlQuery () Source #

`LIMIT`. Limit the number of returned rows.

offset :: Int64 -> SqlQuery () Source #

`OFFSET`. Usually used with `limit`.

distinct :: SqlQuery a -> SqlQuery a Source #

`DISTINCT`. Change the current `SELECT` into `SELECT DISTINCT`. For example:

    select $ distinct $
      from \foo -> do
      ...

Note that this also has the same effect:

    select $
      from \foo -> do
      distinct (return ())
      ...

Since: 2.2.4

distinctOn :: [SqlExpr DistinctOn] -> SqlQuery a -> SqlQuery a Source #

`DISTINCT ON`. Change the current `SELECT` into `SELECT DISTINCT ON (SqlExpressions)`. For example:

    select $
      from \foo ->
      distinctOn [don (foo ^. FooName), don (foo ^. FooState)] $ do
      ...

You can also chain different calls to `distinctOn`. The above is equivalent to:

    select $
      from \foo ->
      distinctOn [don (foo ^. FooName)] $
      distinctOn [don (foo ^. FooState)] $ do
      ...

Each call to `distinctOn` adds more SqlExpressions. Calls to `distinctOn` override any calls to `distinct`.

Note that PostgreSQL requires the SqlExpressions on `DISTINCT ON` to be the first ones to appear on a `ORDER BY`. This is not managed automatically by esqueleto, keeping its spirit of trying to be close to raw SQL.

Supported by PostgreSQL only.

Since: 2.2.4

don :: SqlExpr (Value a) -> SqlExpr DistinctOn Source #

Erase an SqlExpression's type so that it's suitable to be used by `distinctOn`.

Since: 2.2.4

distinctOnOrderBy :: [SqlExpr OrderBy] -> SqlQuery a -> SqlQuery a Source #

A convenience function that calls both `distinctOn` and `orderBy`. In other words,

    distinctOnOrderBy [asc foo, desc bar, desc quux] $ do
      ...

is the same as:

    distinctOn [don foo, don  bar, don  quux] $ do
      orderBy  [asc foo, desc bar, desc quux]
      ...

Since: 2.2.4

having :: SqlExpr (Value Bool) -> SqlQuery () Source #

`HAVING`.

Since: 1.2.2

locking :: LockingKind -> SqlQuery () Source #

Add a locking clause to the query. Please read `LockingKind` documentation and your RDBMS manual.

If multiple calls to `locking` are made on the same query, the last one is used.

Since: 2.2.7

sub_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a) Source #

Deprecated: sub_select sub_select is an unsafe function to use. If used with a SqlQuery that returns 0 results, then it may return NULL despite not mentioning Maybe in the return type. If it returns more than 1 result, then it will throw a SQL error. Instead, consider using one of the following alternatives: - subSelect: attaches a LIMIT 1 and the Maybe return type, totally safe. - subSelectMaybe: Attaches a LIMIT 1, useful for a query that already has a Maybe in the return type. - subSelectCount: Performs a count of the query - this is always safe. - subSelectUnsafe: Performs no checks or guarantees. Safe to use with countRows and friends.

Execute a subquery `SELECT` in an SqlExpression. Returns a simple value so should be used only when the `SELECT` query is guaranteed to return just one row.

Deprecated in 3.2.0.

(^.) :: forall typ val. (PersistEntity val, PersistField typ) => SqlExpr (Entity val) -> EntityField val typ -> SqlExpr (Value typ) infixl 9 Source #

Project a field of an entity.

(?.) :: (PersistEntity val, PersistField typ) => SqlExpr (Maybe (Entity val)) -> EntityField val typ -> SqlExpr (Value (Maybe typ)) Source #

Project a field of an entity that may be null.

val :: PersistField typ => typ -> SqlExpr (Value typ) Source #

Lift a constant value from Haskell-land to the query.

isNothing :: PersistField typ => SqlExpr (Value (Maybe typ)) -> SqlExpr (Value Bool) Source #

`IS NULL` comparison.

just :: SqlExpr (Value typ) -> SqlExpr (Value (Maybe typ)) Source #

Analogous to `Just`, promotes a value of type `typ` into one of type `Maybe typ`. It should hold that ``val` . Just === just . `val``.

nothing :: SqlExpr (Value (Maybe typ)) Source #

`NULL` value.

joinV :: SqlExpr (Value (Maybe (Maybe typ))) -> SqlExpr (Value (Maybe typ)) Source #

Join nested `Maybe`s in a `Value` into one. This is useful when calling aggregate functions on nullable fields.

withNonNull :: PersistField typ => SqlExpr (Value (Maybe typ)) -> (SqlExpr (Value typ) -> SqlQuery a) -> SqlQuery a Source #

Project an SqlExpression that may be null, guarding against null cases.

countRows :: Num a => SqlExpr (Value a) Source #

`COUNT(*)` value.

count :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a) Source #

`COUNT`.

countDistinct :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a) Source #

`COUNT(DISTINCT x)`.

Since: 2.4.1

not_ :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) Source #

(==.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #

(>=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #

(>.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #

(<=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #

(<.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #

(!=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool) infix 4 Source #

(&&.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool) infixr 3 Source #

(||.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool) infixr 2 Source #

between :: PersistField a => SqlExpr (Value a) -> (SqlExpr (Value a), SqlExpr (Value a)) -> SqlExpr (Value Bool) Source #

`BETWEEN`.

@since: 3.1.0

(+.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 6 Source #

(-.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 6 Source #

(/.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 7 Source #

(*.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a) infixl 7 Source #

random_ :: (PersistField a, Num a) => SqlExpr (Value a) Source #

Deprecated: Since 2.6.0: `random_` is not uniform across all databases! Please use a specific one such as `random_`, `random_`, or `random_`

round_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #

ceiling_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #

floor_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #

min_ :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value (Maybe a)) Source #

max_ :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value (Maybe a)) Source #

sum_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b)) Source #

avg_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b)) Source #

castNum :: (Num a, Num b) => SqlExpr (Value a) -> SqlExpr (Value b) Source #

Allow a number of one type to be used as one of another type via an implicit cast. An explicit cast is not made, this function changes only the types on the Haskell side.

Caveat: Trying to use `castNum` from `Double` to `Int` will not result in an integer, the original fractional number will still be used! Use `round_`, `ceiling_` or `floor_` instead.

Safety: This operation is mostly safe due to the `Num` constraint between the types and the fact that RDBMSs usually allow numbers of different types to be used interchangeably. However, there may still be issues with the query not being accepted by the RDBMS or `persistent` not being able to parse it.

Since: 2.2.9

castNumM :: (Num a, Num b) => SqlExpr (Value (Maybe a)) -> SqlExpr (Value (Maybe b)) Source #

Same as `castNum`, but for nullable values.

Since: 2.2.9

coalesce :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value (Maybe a)) Source #

`COALESCE` function. Evaluates the arguments in order and returns the value of the first non-NULL SqlExpression, or NULL (Nothing) otherwise. Some RDBMSs (such as SQLite) require at least two arguments; please refer to the appropriate documentation.

Since: 1.4.3

coalesceDefault :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value a) -> SqlExpr (Value a) Source #

Like `coalesce`, but takes a non-nullable SqlExpression placed at the end of the SqlExpression list, which guarantees a non-NULL result.

Since: 1.4.3

lower_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) Source #

`LOWER` function.

upper_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) Source #

`UPPER` function. Since: 3.3.0

trim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) Source #

`TRIM` function. Since: 3.3.0

ltrim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) Source #

`LTRIM` function. Since: 3.3.0

rtrim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) Source #

`RTRIM` function. Since: 3.3.0

length_ :: (SqlString s, Num a) => SqlExpr (Value s) -> SqlExpr (Value a) Source #

`LENGTH` function. Since: 3.3.0

left_ :: (SqlString s, Num a) => (SqlExpr (Value s), SqlExpr (Value a)) -> SqlExpr (Value s) Source #

`LEFT` function. Since: 3.3.0

right_ :: (SqlString s, Num a) => (SqlExpr (Value s), SqlExpr (Value a)) -> SqlExpr (Value s) Source #

`RIGHT` function. Since: 3.3.0

like :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool) infixr 2 Source #

`LIKE` operator.

ilike :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool) infixr 2 Source #

`ILIKE` operator (case-insensitive `LIKE`).

Supported by PostgreSQL only.

Since: 2.2.3

(%) :: SqlString s => SqlExpr (Value s) Source #

The string ``%``. May be useful while using `like` and concatenation (`concat_` or `++.`, depending on your database). Note that you always have to type the parenthesis, for example:

    name `like` (%) ++. val "John" ++. (%)

concat_ :: SqlString s => [SqlExpr (Value s)] -> SqlExpr (Value s) Source #

The `CONCAT` function with a variable number of parameters. Supported by MySQL and PostgreSQL.

(++.) :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value s) infixr 5 Source #

The `||` string concatenation operator (named after Haskell's `++` in order to avoid naming clash with `||.`). Supported by SQLite and PostgreSQL.

castString :: (SqlString s, SqlString r) => SqlExpr (Value s) -> SqlExpr (Value r) Source #

Cast a string type into `Text`. This function is very useful if you want to use `newtype`s, or if you want to apply functions such as `like` to strings of different types.

Safety: This is a slightly unsafe function, especially if you have defined your own instances of `SqlString`. Also, since `Maybe` is an instance of `SqlString`, it's possible to turn a nullable value into a non-nullable one. Avoid using this function if possible.

subList_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a) Source #

Execute a subquery `SELECT` in an SqlExpression. Returns a list of values.

valList :: PersistField typ => [typ] -> SqlExpr (ValueList typ) Source #

Lift a list of constant value from Haskell-land to the query.

justList :: SqlExpr (ValueList typ) -> SqlExpr (ValueList (Maybe typ)) Source #

Same as `just` but for `ValueList`. Most of the time you won't need it, though, because you can use `just` from inside `subList_select` or `Just` from inside `valList`.

Since: 2.2.12

in_ :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool) Source #

`IN` operator. For example if you want to select all `Person`s by a list of IDs:

    SELECT *
    FROM Person
    WHERE Person.id IN (?)

In `esqueleto`, we may write the same query above as:

    select $
    from $ \person -> do
    where_ $ person ^. PersonId `in_` valList personIds
    return person

Where `personIds` is of type `[Key Person]`.

notIn :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool) Source #

`NOT IN` operator.

exists :: SqlQuery () -> SqlExpr (Value Bool) Source #

`EXISTS` operator. For example:

    select $
    from $ \person -> do
    where_ $ exists $
             from $ \post -> do
             where_ (post ^. BlogPostAuthorId ==. person ^. PersonId)
    return person

notExists :: SqlQuery () -> SqlExpr (Value Bool) Source #

`NOT EXISTS` operator.

set :: PersistEntity val => SqlExpr (Entity val) -> [SqlExpr (Update val)] -> SqlQuery () Source #

`SET` clause used on `UPDATE`s. Note that while it's not a type error to use this function on a `SELECT`, it will most certainly result in a runtime error.

(=.) :: (PersistEntity val, PersistField typ) => EntityField val typ -> SqlExpr (Value typ) -> SqlExpr (Update val) infixr 3 Source #

(+=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #

(-=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #

(*=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #

(/=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val) infixr 3 Source #

case_ :: PersistField a => [(SqlExpr (Value Bool), SqlExpr (Value a))] -> SqlExpr (Value a) -> SqlExpr (Value a) Source #

`CASE` statement. For example:

    select $
    return $
    case_
       [ when_
           (exists $
           from $ \p -> do
           where_ (p ^. PersonName ==. val "Mike"))
         then_
           (sub_select $
           from $ \v -> do
           let sub =
                   from $ \c -> do
                   where_ (c ^. PersonName ==. val "Mike")
                   return (c ^. PersonFavNum)
           where_ (v ^. PersonFavNum >. sub_select sub)
           return $ count (v ^. PersonName) +. val (1 :: Int)) ]
       (else_ $ val (-1))

This query is a bit complicated, but basically it checks if a person named `"Mike"` exists, and if that person does, run the subquery to find out how many people have a ranking (by Fav Num) higher than `"Mike"`.

NOTE: There are a few things to be aware about this statement.

- This only implements the full CASE statement, it does not implement the "simple" CASE statement.
- At least one `when_` and `then_` is mandatory otherwise it will emit an error.
- The `else_` is also mandatory, unlike the SQL statement in which if the `ELSE` is omitted it will return a `NULL`. You can reproduce this via `nothing`.

Since: 2.1.2

toBaseId :: ToBaseId ent => SqlExpr (Value (Key ent)) -> SqlExpr (Value (Key (BaseEnt ent))) Source #

Convert an entity's key into another entity's.

This function is to be used when you change an entity's `Id` to be that of another entity. For example:

    Bar
      barNum Int
    Foo
      bar BarId
      fooNum Int
      Primary bar

In this example, Bar is said to be the BaseEnt(ity), and Foo the child. To model this in Esqueleto, declare:

    instance ToBaseId Foo where
      type BaseEnt Foo = Bar
      toBaseIdWitness barId = FooKey barId

Now you're able to write queries such as:

    select $
    from $ (bar `InnerJoin` foo) -> do
    on (toBaseId (foo ^. FooId) ==. bar ^. BarId)
    return (bar, foo)

Note: this function may be unsafe to use in conditions not like the one of the example above.

Since: 2.4.3

(<#) :: (a -> b) -> SqlExpr (Value a) -> SqlExpr (Insertion b) Source #

Apply a `PersistField` constructor to `SqlExpr Value` arguments.

(<&>) :: SqlExpr (Insertion (a -> b)) -> SqlExpr (Value a) -> SqlExpr (Insertion b) Source #

Apply extra `SqlExpr Value` arguments to a `PersistField` constructor

subSelect :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value (Maybe a)) Source #

Execute a subquery `SELECT` in a `SqlExpr`. The query passed to this function will only return a single result - it has a `LIMIT 1` passed in to the query to make it safe, and the return type is `Maybe` to indicate that the subquery might result in 0 rows.

If you find yourself writing ``joinV` . `subSelect``, then consider using `subSelectMaybe`.

If you're performing a `countRows`, then you can use `subSelectCount` which is safe.

If you know that the subquery will always return exactly one row (eg a foreign key constraint guarantees that you'll get exactly one row), then consider `subSelectUnsafe`, along with a comment explaining why it is safe.

Since: 3.2.0

subSelectMaybe :: PersistField a => SqlQuery (SqlExpr (Value (Maybe a))) -> SqlExpr (Value (Maybe a)) Source #

Execute a subquery `SELECT` in a `SqlExpr`. This function is a shorthand for the common ``joinV` . `subSelect`` idiom, where you are calling `subSelect` on an expression that would be `Maybe` already.

As an example, you would use this function when calling `sum_` or `max_`, which have `Maybe` in the result type (for a 0 row query).

Since: 3.2.0

subSelectCount :: (Num a, PersistField a) => SqlQuery ignored -> SqlExpr (Value a) Source #

Performs a `COUNT` of the given query in a `subSelect` manner. This is always guaranteed to return a result value, and is completely safe.

Since: 3.2.0

subSelectList :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a) Source #

Execute a subquery `SELECT` in a `SqlExpr` that returns a list. This is an alias for `subList_select` and is provided for symmetry with the other safe subselect functions.

Since: 3.2.0

subSelectForeign Source #

Arguments

:: (BackendCompatible SqlBackend (PersistEntityBackend val1), PersistEntity val1, PersistEntity val2, PersistField a) |
=> SqlExpr (Entity val2) | An expression representing the table you have access to now.
-> EntityField val2 (Key val1) | The foreign key field on the table.
-> (SqlExpr (Entity val1) -> SqlExpr (Value a)) | A function to extract a value from the foreign reference table.
-> SqlExpr (Value a) |

Performs a sub-select using the given foreign key on the entity. This is useful to extract values that are known to be present by the database schema.

As an example, consider the following persistent definition:

    User
      profile ProfileId

    Profile
      name    Text

The following query will return the name of the user.

    getUserWithName =
        select $
        from $ user ->
        pure (user, subSelectForeign user UserProfile (^. ProfileName)

Since: 3.2.0

subSelectUnsafe :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a) Source #

Execute a subquery `SELECT` in a `SqlExpr`. This function is unsafe, because it can throw runtime exceptions in two cases:

1. If the query passed has 0 result rows, then it will return a `NULL` value. The `persistent` parsing operations will fail on an unexpected `NULL`.
2. If the query passed returns more than one row, then the SQL engine will fail with an error like "More than one row returned by a subquery used as an expression".

This function is safe if you guarantee that exactly one row will be returned, or if the result already has a `Maybe` type for some reason.

For variants with the safety encoded already, see `subSelect` and `subSelectMaybe`. For the most common safe use of this, see `subSelectCount`.

Since: 3.2.0