lookups.py 文件源码

def process_rhs(self, compiler, connection):
        if hasattr(self.rhs, '_as_sql'):
            # If rhs is some QuerySet, don't touch it
            return super(GISLookup, self).process_rhs(compiler, connection)

        geom = self.rhs
        if isinstance(self.rhs, Col):
            # Make sure the F Expression destination field exists, and
            # set an `srid` attribute with the same as that of the
            # destination.
            geo_fld = self.rhs.output_field
            if not hasattr(geo_fld, 'srid'):
                raise ValueError('No geographic field found in expression.')
            self.rhs.srid = geo_fld.srid
        elif isinstance(self.rhs, Expression):
            raise ValueError('Complex expressions not supported for spatial fields.')
        elif isinstance(self.rhs, (list, tuple)):
            geom = self.rhs[0]
            # Check if a band index was passed in the query argument.
            if ((len(self.rhs) == 2 and not self.lookup_name == 'relate') or
                    (len(self.rhs) == 3 and self.lookup_name == 'relate')):
                self.process_band_indices()
            elif len(self.rhs) > 2:
                raise ValueError('Tuple too long for lookup %s.' % self.lookup_name)
        elif isinstance(self.lhs, RasterBandTransform):
            self.process_band_indices(only_lhs=True)

        rhs, rhs_params = super(GISLookup, self).process_rhs(compiler, connection)
        rhs = connection.ops.get_geom_placeholder(self.lhs.output_field, geom, compiler)
        return rhs, rhs_params