76 lines
2.9 KiB
Python
76 lines
2.9 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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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 = forms.Textarea
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default_error_messages = {
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'no_geom' : _('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', 'GEOMETRY')
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self.null = kwargs.pop('null', True)
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super(GeometryField, self).__init__(**kwargs)
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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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try:
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return GEOSGeometry(value)
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except (GEOSException, ValueError, TypeError):
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raise forms.ValidationError(self.error_messages['invalid_geom'])
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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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if not value:
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if self.null and not self.required:
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# The geometry column allows NULL and is not required.
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return None
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else:
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raise forms.ValidationError(self.error_messages['no_geom'])
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# Transform the value to a python object first
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geom = self.to_python(value)
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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'])
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# Transforming the geometry if the SRID was set.
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if self.srid:
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if not geom.srid:
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# Should match that of the field if not given.
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geom.srid = self.srid
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elif 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:
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raise forms.ValidationError(self.error_messages['transform_error'])
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return geom
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