145 lines
4.5 KiB
Python
145 lines
4.5 KiB
Python
from django import forms
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from django.contrib.gis.gdal import GDALException
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from django.contrib.gis.geos import GEOSException, GEOSGeometry
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from django.core.exceptions import ValidationError
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from django.utils.translation import gettext_lazy as _
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from .widgets import OpenLayersWidget
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class GeometryField(forms.Field):
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"""
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This is the basic form field for a Geometry. Any textual input that is
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accepted by GEOSGeometry is accepted by this form. By default,
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this includes WKT, HEXEWKB, WKB (in a buffer), and GeoJSON.
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"""
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widget = OpenLayersWidget
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geom_type = "GEOMETRY"
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default_error_messages = {
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"required": _("No geometry value provided."),
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"invalid_geom": _("Invalid geometry value."),
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"invalid_geom_type": _("Invalid geometry type."),
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"transform_error": _(
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"An error occurred when transforming the geometry "
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"to the SRID of the geometry form field."
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),
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}
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def __init__(self, *, srid=None, geom_type=None, **kwargs):
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self.srid = srid
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if geom_type is not None:
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self.geom_type = geom_type
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super().__init__(**kwargs)
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self.widget.attrs["geom_type"] = self.geom_type
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def to_python(self, value):
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"""Transform the value to a Geometry object."""
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if value in self.empty_values:
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return None
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if not isinstance(value, GEOSGeometry):
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if hasattr(self.widget, "deserialize"):
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try:
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value = self.widget.deserialize(value)
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except GDALException:
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value = None
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else:
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try:
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value = GEOSGeometry(value)
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except (GEOSException, ValueError, TypeError):
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value = None
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if value is None:
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raise ValidationError(
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self.error_messages["invalid_geom"], code="invalid_geom"
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)
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# Try to set the srid
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if not value.srid:
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try:
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value.srid = self.widget.map_srid
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except AttributeError:
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if self.srid:
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value.srid = self.srid
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return value
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def clean(self, value):
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"""
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Validate that the input value can be converted to a Geometry object
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and return it. Raise a ValidationError if the value cannot be
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instantiated as a Geometry.
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"""
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geom = super().clean(value)
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if geom is None:
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return geom
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# Ensuring that the geometry is of the correct type (indicated
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# using the OGC string label).
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if (
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str(geom.geom_type).upper() != self.geom_type
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and self.geom_type != "GEOMETRY"
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):
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raise ValidationError(
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self.error_messages["invalid_geom_type"], code="invalid_geom_type"
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)
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# Transforming the geometry if the SRID was set.
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if self.srid and self.srid != -1 and self.srid != geom.srid:
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try:
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geom.transform(self.srid)
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except GEOSException:
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raise ValidationError(
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self.error_messages["transform_error"], code="transform_error"
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)
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return geom
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def has_changed(self, initial, data):
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"""Compare geographic value of data with its initial value."""
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try:
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data = self.to_python(data)
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initial = self.to_python(initial)
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except ValidationError:
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return True
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# Only do a geographic comparison if both values are available
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if initial and data:
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data.transform(initial.srid)
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# If the initial value was not added by the browser, the geometry
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# provided may be slightly different, the first time it is saved.
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# The comparison is done with a very low tolerance.
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return not initial.equals_exact(data, tolerance=0.000001)
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else:
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# Check for change of state of existence
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return bool(initial) != bool(data)
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class GeometryCollectionField(GeometryField):
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geom_type = "GEOMETRYCOLLECTION"
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class PointField(GeometryField):
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geom_type = "POINT"
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class MultiPointField(GeometryField):
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geom_type = "MULTIPOINT"
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class LineStringField(GeometryField):
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geom_type = "LINESTRING"
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class MultiLineStringField(GeometryField):
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geom_type = "MULTILINESTRING"
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class PolygonField(GeometryField):
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geom_type = "POLYGON"
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class MultiPolygonField(GeometryField):
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geom_type = "MULTIPOLYGON"
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