在所选内容中禁用换行

如果应用程序想要使用GeoAlChemy 2构建查询并将其作为字符串获取，则使用 ST_AsEWKB() 函数可能很烦人。在这种情况下，可以禁用该包装。此示例使用SQLAlChemy ORM查询。

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

from geoalchemy2 import Geometry


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"
    )