# Django 4.2.11 documentation

# Source code for django.contrib.gis.db.models.fields

    from collections import defaultdict, namedtuple

    from django.contrib.gis import forms, gdal
    from django.contrib.gis.db.models.proxy import SpatialProxy
    from django.contrib.gis.gdal.error import GDALException
    from django.contrib.gis.geos import (
        GeometryCollection,
        GEOSException,
        GEOSGeometry,
        LineString,
        MultiLineString,
        MultiPoint,
        MultiPolygon,
        Point,
        Polygon,
    )
    from django.core.exceptions import ImproperlyConfigured
    from django.db.models import Field
    from django.utils.translation import gettext_lazy as _

    # Local cache of the spatial_ref_sys table, which holds SRID data for each
    # spatial database alias. This cache exists so that the database isn't queried
    # for SRID info each time a distance query is constructed.
    _srid_cache = defaultdict(dict)

    SRIDCacheEntry = namedtuple(
        "SRIDCacheEntry", ["units", "units_name", "spheroid", "geodetic"]
    )

    def get_srid_info(srid, connection):
        """
        Return the units, unit name, and spheroid WKT associated with the
        given SRID from the `spatial_ref_sys` (or equivalent) spatial database
        table for the given database connection.  These results are cached.
        """
        from django.contrib.gis.gdal import SpatialReference

        global _srid_cache

        try:
            # The SpatialRefSys model for the spatial backend.
            SpatialRefSys = connection.ops.spatial_ref_sys()
        except NotImplementedError:
            SpatialRefSys = None

        alias, get_srs = (
            (
                connection.alias,
                lambda srid: SpatialRefSys.objects.using(connection.alias)
                .get(srid=srid)
                .srs,
            )
            if SpatialRefSys
            else (None, SpatialReference)
        )
        if srid not in _srid_cache[alias]:
            srs = get_srs(srid)
            units, units_name = srs.units
            _srid_cache[alias][srid] = SRIDCacheEntry(
                units=units,
                units_name=units_name,
                spheroid='SPHEROID["%s",%s,%s]'
                % (srs["spheroid"], srs.semi_major, srs.inverse_flattening),
                geodetic=srs.geographic,
            )

        return _srid_cache[alias][srid]

    class BaseSpatialField(Field):
        """
        The Base GIS Field.

        It's used as a base class for GeometryField and RasterField. Defines
        properties that are common to all GIS fields such as the characteristics
        of the spatial reference system of the field.
        """

        description = _("The base GIS field.")
        empty_strings_allowed = False

        def __init__(self, verbose_name=None, srid=4326, spatial_index=True, **kwargs):
            """
            The initialization function for base spatial fields. Takes the following
            as keyword arguments:

            srid:
             The spatial reference system identifier, an OGC standard.
             Defaults to 4326 (WGS84).

            spatial_index:
             Indicates whether to create a spatial index.  Defaults to True.
             Set this instead of 'db_index' for geographic fields since index
             creation is different for geometry columns.
            """

            # Setting the index flag with the value of the `spatial_index` keyword.
            self.spatial_index = spatial_index

            # Setting the SRID and getting the units.  Unit information must be
            # easily available in the field instance for distance queries.
            self.srid = srid

            # Setting the verbose_name keyword argument with the positional
            # first parameter, so this works like normal fields.
            kwargs["verbose_name"] = verbose_name

            super().__init__(**kwargs)

        def deconstruct(self):
            name, path, args, kwargs = super().deconstruct()
            # Always include SRID for less fragility; include spatial index if it's
            # not the default value.
            kwargs["srid"] = self.srid
            if self.spatial_index is not True:
                kwargs["spatial_index"] = self.spatial_index
            return name, path, args, kwargs

        def db_type(self, connection):
            return connection.ops.geo_db_type(self)

        def spheroid(self, connection):
            return get_srid_info(self.srid, connection).spheroid

        def units(self, connection):
            return get_srid_info(self.srid, connection).units

        def units_name(self, connection):
            return get_srid_info(self.srid, connection).units_name

        def geodetic(self, connection):
            """
            Return true if this field's SRID corresponds with a coordinate
            system that uses non-projected units (e.g., latitude/longitude).
            """
            return get_srid_info(self.srid, connection).geodetic

        def get_placeholder(self, value, compiler, connection):
            """
            Return the placeholder for the spatial column for the
            given value.
            """
            return connection.ops.get_geom_placeholder(self, value, compiler)

        def get_srid(self, obj):
            """
            Return the default SRID for the given geometry or raster, taking into
            account the SRID set for the field. For example, if the input geometry
            or raster doesn't have an SRID, then the SRID of the field will be
            returned.
            """
            srid = obj.srid  # SRID of given geometry.
            if srid is None or self.srid == -1 or (srid == -1 and self.srid != -1):
                return self.srid
            else:
                return srid

        def get_db_prep_value(self, value, connection, *args, **kwargs):
            if value is None:
                return None
            return connection.ops.Adapter(
                super().get_db_prep_value(value, connection, *args, **kwargs),
                **(
                    {"geography": True}
                    if self.geography and connection.features.supports_geography
                    else {}
                ),
            )

        def get_raster_prep_value(self, value, is_candidate):
            """
            Return a GDALRaster if conversion is successful, otherwise return None.
            """
            if isinstance(value, gdal.GDALRaster):
                return value
            elif is_candidate:
                try:
                    return gdal.GDALRaster(value)
                except GDALException:
                    pass
            elif isinstance(value, dict):
                try:
                    return gdal.GDALRaster(value)
                except GDALException:
                    raise ValueError(
                        "Couldn't create spatial object from lookup value '%s'." % value
                    )

        def get_prep_value(self, value):
            obj = super().get_prep_value(value)
            if obj is None:
                return None
            # When the input is not a geometry or raster, attempt to construct one
            # from the given string input.
            if isinstance(obj, GEOSGeometry):
                pass
            else:
                # Check if input is a candidate for conversion to raster or geometry.
                is_candidate = isinstance(obj, (bytes, str)) or hasattr(
                    obj, "__geo_interface__"
                )
                # Try to convert the input to raster.
                raster = self.get_raster_prep_value(obj, is_candidate)

                if raster:
                    obj = raster
                elif is_candidate:
                    try:
                        obj = GEOSGeometry(obj)
                    except (GEOSException, GDALException):
                        raise ValueError(
                            "Couldn't create spatial object from lookup value '%s'." % obj
                        )
                else:
                    raise ValueError(
                        "Cannot use object with type %s for a spatial lookup parameter."
                        % type(obj).__name__
                    )

            # Assigning the SRID value.
            obj.srid = self.get_srid(obj)
            return obj

    class GeometryField(BaseSpatialField):
        """
        The base Geometry field -- maps to the OpenGIS Specification Geometry type.
        """

        description = _(
            "The base Geometry field — maps to the OpenGIS Specification Geometry type."
        )
        form_class = forms.GeometryField
        # The OpenGIS Geometry name.
        geom_type = "GEOMETRY"
        geom_class = None

        def __init__(
            self,
            verbose_name=None,
            dim=2,
            geography=False,
            *,
            extent=(-180.0, -90.0, 180.0, 90.0),
            tolerance=0.05,
            **kwargs,
        ):
            """
            The initialization function for geometry fields. In addition to the
            parameters from BaseSpatialField, it takes the following as keyword
            arguments:

            dim:
             The number of dimensions for this geometry.  Defaults to 2.

            extent:
             Customize the extent, in a 4-tuple of WGS 84 coordinates, for the
             geometry field entry in the `USER_SDO_GEOM_METADATA` table.  Defaults
             to (-180.0, -90.0, 180.0, 90.0).

            tolerance:
             Define the tolerance, in meters, to use for the geometry field
             entry in the `USER_SDO_GEOM_METADATA` table.  Defaults to 0.05.
            """
            # Setting the dimension of the geometry field.
            self.dim = dim

            # Is this a geography rather than a geometry column?
            self.geography = geography

            # Oracle-specific private attributes for creating the entry in
            # `USER_SDO_GEOM_METADATA`
            self._extent = extent
            self._tolerance = tolerance

            super().__init__(verbose_name=verbose_name, **kwargs)

        def deconstruct(self):
            name, path, args, kwargs = super().deconstruct()
            # Include kwargs if they're not the default values.
            if self.dim != 2:
                kwargs["dim"] = self.dim
            if self.geography is not False:
                kwargs["geography"] = self.geography
            if self._extent != (-180.0, -90.0, 180.0, 90.0):
                kwargs["extent"] = self._extent
            if self._tolerance != 0.05:
                kwargs["tolerance"] = self._tolerance
            return name, path, args, kwargs

        def contribute_to_class(self, cls, name, **kwargs):
            super().contribute_to_class(cls, name, **kwargs)

            # Setup for lazy-instantiated Geometry object.
            setattr(
                cls,
                self.attname,
                SpatialProxy(self.geom_class or GEOSGeometry, self, load_func=GEOSGeometry),
            )

        def formfield(self, **kwargs):
            defaults = {
                "form_class": self.form_class,
                "geom_type": self.geom_type,
                "srid": self.srid,
                **kwargs,
            }
            if self.dim > 2 and not getattr(
                defaults["form_class"].widget, "supports_3d", False
            ):
                defaults.setdefault("widget", forms.Textarea)
            return super().formfield(**defaults)

        def select_format(self, compiler, sql, params):
            """
            Return the selection format string, depending on the requirements
            of the spatial backend. For example, Oracle and MySQL require custom
            selection formats in order to retrieve geometries in OGC WKB.
            """
            if not compiler.query.subquery:
                return compiler.connection.ops.select % sql, params
            return sql, params

    # The OpenGIS Geometry Type Fields

    class PointField(GeometryField):
        geom_type = "POINT"
        geom_class = Point
        form_class = forms.PointField
        description = _("Point")

    class LineStringField(GeometryField):
        geom_type = "LINESTRING"
        geom_class = LineString
        form_class = forms.LineStringField
        description = _("Line string")

    class PolygonField(GeometryField):
        geom_type = "POLYGON"
        geom_class = Polygon
        form_class = forms.PolygonField
        description = _("Polygon")

    class MultiPointField(GeometryField):
        geom_type = "MULTIPOINT"
        geom_class = MultiPoint
        form_class = forms.MultiPointField
        description = _("Multi-point")

    class MultiLineStringField(GeometryField):
        geom_type = "MULTILINESTRING"
        geom_class = MultiLineString
        form_class = forms.MultiLineStringField
        description = _("Multi-line string")

    class MultiPolygonField(GeometryField):
        geom_type = "MULTIPOLYGON"
        geom_class = MultiPolygon
        form_class = forms.MultiPolygonField
        description = _("Multi polygon")

    class GeometryCollectionField(GeometryField):
        geom_type = "GEOMETRYCOLLECTION"
        geom_class = GeometryCollection
        form_class = forms.GeometryCollectionField
        description = _("Geometry collection")

    class ExtentField(Field):
        "Used as a return value from an extent aggregate"

        description = _("Extent Aggregate Field")

        def get_internal_type(self):
            return "ExtentField"

        def select_format(self, compiler, sql, params):
            select = compiler.connection.ops.select_extent
            return select % sql if select else sql, params

    class RasterField(BaseSpatialField):
        """
        Raster field for GeoDjango -- evaluates into GDALRaster objects.
        """

        description = _("Raster Field")
        geom_type = "RASTER"
        geography = False

        def _check_connection(self, connection):
            # Make sure raster fields are used only on backends with raster support.
            if (
                not connection.features.gis_enabled
                or not connection.features.supports_raster
            ):
                raise ImproperlyConfigured(
                    "Raster fields require backends with raster support."
                )

        def db_type(self, connection):
            self._check_connection(connection)
            return super().db_type(connection)

        def from_db_value(self, value, expression, connection):
            return connection.ops.parse_raster(value)

        def contribute_to_class(self, cls, name, **kwargs):
            super().contribute_to_class(cls, name, **kwargs)
            # Setup for lazy-instantiated Raster object. For large querysets, the
            # instantiation of all GDALRasters can potentially be expensive. This
            # delays the instantiation of the objects to the moment of evaluation
            # of the raster attribute.
            setattr(cls, self.attname, SpatialProxy(gdal.GDALRaster, self))

        def get_transform(self, name):
            from django.contrib.gis.db.models.lookups import RasterBandTransform

            try:
                band_index = int(name)
                return type(
                    "SpecificRasterBandTransform",
                    (RasterBandTransform,),
                    {"band_index": band_index},
                )
            except ValueError:
                pass
            return super().get_transform(name)