Merged the gis branch into trunk.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8219 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/forms/fields.py

@@ -0,0 +1,37 @@
+from django import forms
+from django.contrib.gis.geos import GEOSGeometry, GEOSException
+from django.utils.translation import ugettext_lazy as _
+
+class GeometryField(forms.Field):
+    # By default a Textarea widget is used.
+    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:
+            geom = GEOSGeometry(value)
+            if geom.geom_type.upper() != self.geom_type:
+                raise forms.ValidationError(self.error_messages['invalid_geom_type'])
+            return geom
+        except GEOSException:
+            raise forms.ValidationError(self.error_messages['invalid_geom'])