query.py 文件源码

def geojson(self, precision=8, crs=False, bbox=False, **kwargs):
        """
        Returns a GeoJSON representation of the geometry field in a `geojson`
        attribute on each element of the GeoQuerySet.

        The `crs` and `bbox` keywords may be set to True if the user wants
        the coordinate reference system and the bounding box to be included
        in the GeoJSON representation of the geometry.
        """
        backend = connections[self.db].ops
        if not backend.geojson:
            raise NotImplementedError('Only PostGIS and SpatiaLite support GeoJSON serialization.')

        if not isinstance(precision, six.integer_types):
            raise TypeError('Precision keyword must be set with an integer.')

        options = 0
        if crs and bbox:
            options = 3
        elif bbox:
            options = 1
        elif crs:
            options = 2
        s = {'desc': 'GeoJSON',
             'procedure_args': {'precision': precision, 'options': options},
             'procedure_fmt': '%(geo_col)s,%(precision)s,%(options)s',
             }
        return self._spatial_attribute('geojson', s, **kwargs)