131 lines
4.3 KiB
Python
131 lines
4.3 KiB
Python
from __future__ import unicode_literals
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from django import forms
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from django.utils.translation import ugettext_lazy as _
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# While this couples the geographic forms to the GEOS library,
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# it decouples from database (by not importing SpatialBackend).
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from django.contrib.gis.geos import GEOSException, GEOSGeometry
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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': _('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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def __init__(self, **kwargs):
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# Pop out attributes from the database field, or use sensible
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# defaults (e.g., allow None).
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self.srid = kwargs.pop('srid', None)
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self.geom_type = kwargs.pop('geom_type', self.geom_type)
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super(GeometryField, self).__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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"""
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Transforms the value to a Geometry object.
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"""
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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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try:
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value = GEOSGeometry(value)
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except (GEOSException, ValueError, TypeError):
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raise forms.ValidationError(self.error_messages['invalid_geom'], code='invalid_geom')
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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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Validates that the input value can be converted to a Geometry
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object (which is returned). A ValidationError is raised if
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the value cannot be instantiated as a Geometry.
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"""
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geom = super(GeometryField, self).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 str(geom.geom_type).upper() != self.geom_type and not self.geom_type == 'GEOMETRY':
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raise forms.ValidationError(self.error_messages['invalid_geom_type'], code='invalid_geom_type')
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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 forms.ValidationError(
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self.error_messages['transform_error'], code='transform_error')
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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 forms.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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