# Fields

Fields define the behavior of the data on model’s record.

## Field options

The following arguments are available to all field types. All are optional except `Field.string`.

### `string`

`Field.``string`

A string for the label of the field.

### `help`

`Field.``help`

A multi-line help string for the field.

### `required`

`Field.``required`

If `True`, the field is not allowed to be empty. Default is `False`.

### `readonly`

`Field.``readonly`

If `True`, the field is not editable in the client. Default is `False`.

Warning

For relational fields, it means only the new, delete, add and remove buttons are inactivated. The editable state of the target record must be managed at the target model level.

### `domain`

`Field.``domain`

A domain constraint that will be applied on the field value.

### `states`

`Field.``states`

A dictionary that defines dynamic states of the field and overrides the static one. Possible keys are `required`, `readonly` and `invisible`. The values are `PYSON` statements that will be evaluated with the values of the record.

### `select`

`Field.``select`

If true, the content of the field will be indexed.

### `on_change`

`Field.``on_change`

A set of field names. If this attribute is set, the client will call the method `on_change_<field name>` of the model when the user changes the current field value and will give the values of each fields in this list. The method signature is:

    on_change_<field name>()

This method must change the value of the fields to be updated.

Note

The on_change_<field name> methods are running in a rollbacked transaction.

The set of field names could be filled by using the decorator `depends()`.

### `on_change_with`

`Field.``on_change_with`

A set of field names. Same like `on_change`, but defined the other way around. If this attribute is set, the client will call the method `on_change_with_<field name>` of the model when the user changes one of the fields defined in the list and will give the values of each fields in this list. The method signature is:

    on_change_with_<field name>()

This method must return the new value of the field.

Note

The on_change_with_<field name> methods are running in a rollbacked transaction.

The set of field names could be filled by using the decorator `depends()`.

### `depends`

`Field.``depends`

A list of field names on which the current one depends. This means that the client will also read these fields even if they are not defined on the view. `Field.depends` is used per example to ensure that `PYSON` statement could be evaluated.

### `context`

`Field.``context`

A dictionary which will update the current context for relation field.

Warning

The context could only depend on direct field of the record and without context.

### `loading`

`Field.``loading`

Define how the field must be loaded: `lazy` or `eager`.

### `name`

`Field.``name`

The name of the field.

Instance methods:

`Field.``convert_domain`(domain, tables, Model)

  Convert the simple domain clause into a SQL expression or a new domain. tables could be updated to add new joins.

`Field.``sql_format`(value)

  Convert the value to use as parameter of SQL queries.

`Field.``sql_type`()

  Return the namedtuple(‘SQLType’, ‘base type’) which defines the SQL type to use for creation and casting. Or None if the field is not stored in the database.

  sql_type is using the _sql_type attribute to compute its return value. The backend is responsible for the computation.

  For the list of supported types by Tryton see backend types.

`Field.``sql_cast`(expression)

  Return the SQL expression with cast with the type of the field.

`Field.``sql_column`(table)

  Return the Column instance based on table.

`Field.``set_rpc`(model)

  Adds to model the default RPC instances required by the field.

## Default value

See default value

## Searching

A class method could be defined for each field which must return a SQL expression for the given domain instead of the default one. The method signature is:

    domain_<field name>(domain, tables)

Where `domain` is the simple domain clause and `tables` is a nested dictionary, see `convert_domain()`.

## Ordering

A class method could be defined for each field which must return a list of SQL expression on which to order instead of the field. The method signature is:

    order_<field name>(tables)

Where `tables` is a nested dictionary, see `convert_domain()`.

## Depends

`trytond.model.fields.``depends`([*fields[, methods]])

A decorator to define the field names on which the decorated method depends. The methods argument can be used to duplicate the field names from other decorated methods. This is useful if the decorated method calls another method.

## Field types

### Boolean

class `trytond.model.fields.``Boolean`(string[, **options])

A true/false field.

### Integer

class `trytond.model.fields.``Integer`(string[, **options])

An integer field.

### BigInteger

class `trytond.model.fields.``BigInteger`(string[, **options])

A long integer field.

### Char

class `trytond.model.fields.``Char`(string[, size[, translate[, **options]]])

A single line string field.

`Char` has two extra optional arguments:

`Char.``size`

  The maximum length (in characters) of the field. The size is enforced at the storage level and in the client input.

`Char.``translate`

  If true, the value of the field is translatable. The value readed and stored will depend on the `language` defined in the context.

`Char.``autocomplete`

  A set of field names. If this attribute is set, the client will call the method `autocomplete_<field name>` of the model when the user changes one of those field value. The method signature is:

      autocomplete_<field name>()

  This method must return a list of string that will populate the ComboboxEntry in the client. The set of field names could be filled by using the decorator `depends()`.

`Char.``search_unaccented`

  If this attribute is set to True, `ilike` searches will be performed on unaccented strings. The default value is True.

Warning

The database backend must supports unaccented search.

### Text

class `trytond.model.fields.``Text`(string[, size[, translatable[, **options]]])

A multi line string field.

`Text` has two extra optional arguments:

`Text.``size`

  Same as `Char.size`

`Text.``translate`

  Same as `Char.translate`

### Float

class `trytond.model.fields.``Float`(string[, digits[, **options]])

A floating-point number field. It will be represented in Python by a `float` instance.

`Float` has one extra optional arguments:

`Float.``digits`

  A tuple of two integers. The first integer defines the total of numbers in the integer part. The second integer defines the total of numbers in the decimal part. Integers can be replaced by a `PYSON` statement. If digits is None or any values of the tuple is None, no validation on the numbers will be done.

### Numeric

class `trytond.model.fields.``Numeric`(string[, digits[, **options]])

A fixed-point number field. It will be represented in Python by a `decimal.Decimal` instance.

`Numeric` has one extra optional arguments:

`Numeric.``digits`

  Same as `Float.digits`

### Date

class `trytond.model.fields.``Date`(string[, **options])

A date, represented in Python by a `datetime.date` instance.

### DateTime

class `trytond.model.fields.``DateTime`(string[, format, **options])

A date and time, represented in Python by a `datetime.datetime` instance. It is stored in UTC while displayed in the user timezone.

`DateTime.``format`

  A string format as used by strftime. This format will be used to display the time part of the field. The default value is %H:%M:%S. The value can be replaced by a `PYSON` statement.

### Timestamp

class `trytond.model.fields.``Timestamp`(string[, **options])

A timestamp, represented in Python by a `datetime.datetime` instance.

### Time

class `trytond.model.fields.``Time`(string[, format, **options])

A time, represented in Python by a `datetime.time` instance.

`Time.``format`

  Same as `DateTime.format`

### TimeDelta

class `trytond.model.fields.``TimeDelta`(string[, converter[, **options]])

An interval, represented in Python by a `datetime.timedelta` instance.

`TimeDelta.``converter`

  The name of the context key containing the time converter. A time converter is a dictionary with the keys: `s` (second), `m` (minute), `h` (hour), `d` (day), `w` (week), `M` (month), `Y` (year) and the value in second.

### Binary

class `trytond.model.fields.``Binary`(string[, **options])

A binary field. It will be represented in Python by a `bytes` instance.

Warning

If the context contains a key composed of the model name and field name separated by a dot and its value is the string size then the read value is the size instead of the content.

`Binary` has three extra optional arguments:

`Binary.``filename`

  Name of the field that holds the data’s filename. Default value is an empty string, which means the data has no filename (in this case, the filename is hidden, and the “Open” button is hidden when the widget is set to “image”).

`Binary.``file_id`

  Name of the field that holds the FileStore identifier. Default value is None which means the data is stored in the database. The field must be on the same table and accept char values.

Warning

Switching from database to file-store is supported transparently. But switching from file-store to database is not supported without manually upload to the database all the files.

`Binary.``store_prefix`

  The prefix to use with the FileStore. Default value is None which means the database name is used.

### Selection

class `trytond.model.fields.``Selection`(selection, string[, sort[, selection_change_with[, translate[, **options]]])

A string field with limited values to choice.

`Selection` has one extra required argument:

`Selection.``selection`

  A list of 2-tuples that looks like this:

      [
          ('M', 'Male'),
          ('F', 'Female'),
      ]

  The first element in each tuple is the actual value stored. The second element is the human-readable name.

  It can also be the name of a class or instance method on the model, that will return an appropriate list. The signature of the method is:

      selection()

  Note

  The method is automaticly added to `trytond.model.Model._rpc` if not manually set.

`Selection` has two extra optional arguments:

`Selection.``sort`

  If true, the choices will be sorted by human-readable value. Default value is `True`.

`Selection.``selection_change_with`

  A set of field names. If this attribute is set, the client will call the `selection` method of the model when the user changes on of the fields defined in the list and will give the values of each fields in the list. The `selection` method should be an instance method. The set of field names could be filled by using the decorator `depends()`.

`Selection.``translate_selection`

  If true, the human-readable values will be translated. Default value is `True`.

Instance methods:

`Selection.``translated`([name])

  Returns a descriptor for the translated value of the field. The descriptor must be used on the same class as the field. It will use the language defined in the context of the instance accessed.

### Reference

class `trytond.model.fields.``Reference`(string[, selection[, selection_change_with[, search_order[, search_context[, **options]]]])

A field that refers to a record of a model. It will be represented in Python by a `str` instance like this:

    '<model name>,<record id>'

But a `tuple` can be used to search or set value.

`Reference` has three extra optional arguments:

`Reference.``selection`

  Same as `Selection.selection` but only for model name.

`Reference.``selection_change_with`

  Same as `Selection.selection_change_with`.

`Reference.``datetime_field`

  Same as `Many2One.datetime_field`

`Reference.``search_order`

  Same as `Many2One.search_order`

`Reference.``search_context`

  Same as `Many2One.search_context`

Instance methods:

`Reference.``translated`([name])

  Same as `translated()` but for the translated name of the target model.

### Many2One

class `trytond.model.fields.``Many2One`(model_name, string[, left[, right[, ondelete[, datetime_field[, target_search[, search_order[, search_context[, **options]]]]]]])

A many-to-one relation field.

`Many2One` has one extra required argument:

`Many2One.``model_name`

  The name of the target model.

`Many2One` has some extra optional arguments:

`Many2One.``left`

  The name of the field that stores the left value for the Modified Preorder Tree Traversal. It only works if the `model_name` is the same then the model.

Warning

The MPTT Tree will be rebuild on database update if one record is found having left or right field value equals to the default or NULL.

`Many2One.``right`

  The name of the field that stores the right value. See `left`.

`Many2One.``ondelete`

  Define the behavior of the record when the target record is deleted. Allowed values are:

  > - `CASCADE`: it will try to delete the record.
  > - `RESTRICT`: it will prevent the deletion of the target record.
  > - `SET NULL`: it will empty the relation field.

  `SET NULL` is the default setting.

  Note

  `SET NULL` will be override into `RESTRICT` if `required` is true.

`Many2One.``datetime_field`

  If set, the target record will be read at the date defined by the datetime field name of the record. It is usually used in combination with `trytond.model.ModelSQL._history` to request a value for a given date and time on a historicized model.

`Many2One.``target_search`

  Define the kind of SQL query to use when searching on related target. Allowed values are:

  > - `subquery`: it will use a subquery based on the ids.
  > - `join`: it will add a join on the main query.

  `join` is the default value.

  Note

  `join` could improve the performance if the target has a huge amount of records.

`Many2One.``search_order`

  A PYSON expression defining the default order used to display search results in the clients.

`Many2One.``search_context`

  A dictionary defining the default context used when searching from the client.

  Beware that `search_context` will override the values from the client `context`.

### One2Many

class `trytond.model.fields.``One2Many`(model_name, field, string[, add_remove[, order[, datetime_field[, size[, search_order[, search_context[, **options]]]]]]])

A one-to-many relation field. It requires to have the opposite `Many2One` field or a `Reference` field defined on the target model.

This field accepts as written value a list of tuples like this:

> - `('create', [{<field name>: value, ...}, ...])`: it will create new target records and link them to this one.
> - `('write'[[, ids, ...], {<field name>: value, ...}, ...])`: it will write values to target ids.
> - `('delete'[, ids, ...])`: it will delete the target ids.
> - `('add'[, ids, ...])`: it will link the target ids to this record.
> - `('remove'[, ids, ...])`: it will unlink the target ids from this record.
> - `('copy', ids[, {<field name>: value, ...}])`: it will copy the target ids to this record. Optional field names and values may be added to override some of the fields of the copied records.

Note

`PYSON` statement or `Field.depends` of target records can access value of the parent record fields by prepending `_parent_` to the opposite field name and followed by the dotted notation.

`One2Many` has some extra required arguments:

`One2Many.``model_name`

  The name of the target model.

`One2Many.``field`

  The name of the field that handles the opposite `Many2One` or `Reference`.

`One2Many` has some extra optional arguments:

`One2Many.``add_remove`

  A domain to select records to add. If set, the client will allow to add/remove existing records instead of only create/delete.

`One2Many.``filter`

  A domain that is not a constraint but only a filter on the records.

`One2Many.``order`

  A list of tuple defining the default order of the records like for `trytond.model.ModelSQL._order`.

`One2Many.``datetime_field`

  Same as `Many2One.datetime_field`

`One2Many.``size`

  An integer or a PYSON expression denoting the maximum number of records allowed in the relation.

`One2Many.``search_order`

  Same as `Many2One.search_order`

`One2Many.``search_context`

  Same as `Many2One.search_context`

### Many2Many

class `trytond.model.fields.``Many2Many`(relation_name, origin, target, string[, order[, datetime_field[, size[, search_order[, search_context[, **options]]]]]])

A many-to-many relation field. It requires to have the opposite origin `Many2One` field or a:class:Reference field defined on the relation model and a `Many2One` field pointing to the target.

This field accepts as written value a list of tuples like the `One2Many`.

`Many2Many` has some extra required arguments:

`Many2Many.``relation_name`

  The name of the relation model.

`Many2Many.``origin`

  The name of the field that has the `Many2One` or `Reference` to the record.

`Many2Many.``target`

  The name of the field that has the `Many2One` to the target record.

Note

A `Many2Many` field can be used on a simple `ModelView`, like in a `Wizard`. For this, `relation_name` is set to the target model and `origin` and `target` are set to None.

`Many2Many` has some extra optional arguments:

`Many2Many.``order`

  Same as `One2Many.order`

`Many2Many.``datetime_field`

  Same as `Many2One.datetime_field`

`Many2Many.``size`

  An integer or a PYSON expression denoting the maximum number of records allowed in the relation.

`Many2Many.``add_remove`

  An alias to the `domain` for compatibility with the `One2Many`.

`Many2Many.``filter`

  Same as `One2Many.filter`

Instance methods:

`Many2Many.``get_target`()

  Return the target `Model`.

`Many2Many.``search_order`

  Same as `Many2One.search_order`

`Many2Many.``search_context`

  Same as `Many2One.search_context`

### One2One

class `trytond.model.fields.``One2One`(relation_name, origin, target, string[, datetime_field[, **options]])

A one-to-one relation field.

Warning

It is on the relation_name `Model` that the unicity of the couple (origin, target) must be checked.

`One2One.``datetime_field`

  Same as `Many2One.datetime_field`

`One2One.``filter`

  Same as `One2Many.filter`

Instance methods:

`One2One.``get_target`()

  Return the target `Model`.

### Function

class `trytond.model.fields.``Function`(field, getter[, setter[, searcher]])

A function field can emulate any other given field.

`Function` has a required argument:

`Function.``getter`

  The name of the classmethod or instance of the `Model` for getting values. The signature of the classmethod is:

      getter(instances, name)

  where name is the name of the field, and it must return a dictionary with a value for each instance.

  Or the signature of the classmethod is:

      getter(instances, names)

  where names is a list of name fields, and it must return a dictionary containing for each names a dictionary with a value for each instance.

  The signature of the instancemethod is:

      getter(name)

  where name is the name of the field, and it must return the value.

`Function` has some extra optional arguments:

`Function.``setter`

  The name of the classmethod of the `Model` to set the value. The signature of the method id:

      setter(instances, name, value)

  where name is the name of the field and value the value to set.

Warning

The modifications made to instances will not be saved automatically.

`Function.``searcher`

  The name of the classmethod of the `Model` to search on the field. The signature of the method is:

      searcher(name, clause)

  where name is the name of the field and clause is a domain clause. It must return a list of domain clauses but the `operand` can be a SQL query.

Instance methods:

`Function.``get`(ids, model, name[, values])

  Call the `getter` classmethod where model is the `Model` instance of the field, name is the name of the field.

`Function.``set`(ids, model, name, value)

  Call the `setter` classmethod where model is the `Model` instance of the field, name is the name of the field, value is the value to set.

`Function.``search`(model, name, clause)

  Call the `searcher` classmethod where model is the `Model` instance of the field, name is the name of the field, clause is a clause of domain.

### MultiValue

class `trytond.model.fields.``MultiValue`(field)

A multivalue field that is like a `Function` field but with predefined `getter` and `setter` that use the `MultiValueMixin` for stored values.

Warning

The `get_multivalue()` and `set_multivalue()` should be prefered over the descriptors of the field.

Warning

The default method of the field must accept pattern as keyword argument.

### Dict

class `trytond.model.fields.``Dict`(schema_model[, **options])

A dictionary field with predefined keys.

Note

It is possible to store the dict as JSON in the database if the backend supports by manually altering the column type to JSON on the database.

`Dict` has one extra required argument:

`Dict.``schema_model`

  The name of the `DictSchemaMixin` model that stores the definition of keys.

Instance methods:

`Dict.``translated`([name[, type_]])

  Returns a descriptor for the translated values or keys of the field following type_. The descriptor must be used on the same class as the field. Default type_ is values.