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from django import forms
from django.contrib.gis.db.backend import SpatialBackend
from django.utils.translation import ugettext_lazy as _
class GeometryField(forms.Field):
"""
This is the basic form field for a Geometry. Any textual input that is
accepted by SpatialBackend.Geometry is accepted by this form. By default,
this is GEOSGeometry, which accepts WKT, HEXEWKB, WKB, and GeoJSON.
"""
widget = forms.Textarea
default_error_messages = {
'no_geom' : _(u'No geometry value provided.'),
'invalid_geom' : _(u'Invalid geometry value.'),
'invalid_geom_type' : _(u'Invalid geometry type.'),
}
def __init__(self, **kwargs):
self.null = kwargs.pop('null')
self.geom_type = kwargs.pop('geom_type')
super(GeometryField, self).__init__(**kwargs)
def clean(self, value):
"""
Validates that the input value can be converted to a Geometry
object (which is returned). A ValidationError is raised if
the value cannot be instantiated as a Geometry.
"""
if not value:
if self.null:
# The geometry column allows NULL, return None.
return None
else:
raise forms.ValidationError(self.error_messages['no_geom'])
try:
# Trying to create a Geometry object from the form value.
geom = SpatialBackend.Geometry(value)
except:
raise forms.ValidationError(self.error_messages['invalid_geom'])
# Ensuring that the geometry is of the correct type (indicated
# using the OGC string label).
if str(geom.geom_type).upper() != self.geom_type and not self.geom_type == 'GEOMETRY':
raise forms.ValidationError(self.error_messages['invalid_geom_type'])
return geom
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