Disable wrapping in select

If the application wants to build queries with GeoAlchemy 2 and gets them as strings, the wrapping of geometry columns with a ST_AsEWKB() function might be annoying. In this case it is possible to disable this wrapping. This example uses SQLAlchemy ORM queries.

 from sqlalchemy import Column
 from sqlalchemy import Integer
 from sqlalchemy import func
 from sqlalchemy.ext.declarative import declarative_base

 from geoalchemy2 import Geometry

 # Tests imports
 from tests import select

 Base = declarative_base()


 class RawGeometry(Geometry):
     """This class is used to remove the 'ST_AsEWKB()'' function from select queries"""

     def column_expression(self, col):
         return col


 class Point(Base):
     __tablename__ = "point"
     id = Column(Integer, primary_key=True)
     geom = Column(Geometry(srid=4326, geometry_type="POINT"))
     raw_geom = Column(
         RawGeometry(srid=4326, geometry_type="POINT"))


 def test_no_wrapping():
     # Select all columns
     select_query = select([Point])

     # Check that the 'geom' column is wrapped by 'ST_AsEWKB()' and that the column
     # 'raw_geom' is not.
     assert str(select_query) == (
         "SELECT point.id, ST_AsEWKB(point.geom) AS geom, point.raw_geom \n"
         "FROM point"
     )


 def test_func_no_wrapping():
     # Select query with function
     select_query = select([
         func.ST_Buffer(Point.geom),  # with wrapping (default behavior)
         func.ST_Buffer(Point.geom, type_=Geometry),  # with wrapping
         func.ST_Buffer(Point.geom, type_=RawGeometry)  # without wrapping
     ])

     # Check the query
     assert str(select_query) == (
         "SELECT "
         "ST_AsEWKB(ST_Buffer(point.geom)) AS \"ST_Buffer_1\", "
         "ST_AsEWKB(ST_Buffer(point.geom)) AS \"ST_Buffer_2\", "
         "ST_Buffer(point.geom) AS \"ST_Buffer_3\" \n"
         "FROM point"
     )