SQLAlchemy中filter()和filter_by()有什么区别
from:https://segmentfault.com/q/1010000000140472
apply the given filtering criterion to a copy of this Query, using SQL expressions.
e.g.:
session.query(MyClass).filter(MyClass.name == 'some name')
apply the given filtering criterion to a copy of this Query, using keyword expressions.
e.g.:
session.query(MyClass).filter_by(name = 'some name')
确实,filter用类名.属性名,比较用==,filter_by直接用属性名,比较用=
不过这个是语法小细节。个人觉得最重要的区别是filter不支持组合查询,只能连续调用filter来变相实现。
而filter_by的参数是**kwargs
,直接支持组合查询。
比如:
q = sess.query(IS).filter(IS.node == node and IS.password == password).all()
对应的sql是SELECT tb_is.id AS tb_is_id, tb_is.node AS tb_is_node, tb_is.password AS tb_is_password, tb_is.email AS tb_is_email, tb_is.`admin` AS tb_is_admin, tb_is.contact AS tb_is_contact, tb_is.is_available AS tb_is_is_available, tb_is.is_url AS tb_is_is_url, tb_is.note AS tb_is_note
FROM tb_is
WHERE tb_is.node = %(node_1)sand后面的条件既不报错,又不生效,很坑。
要实现组合查询,要么连续调用filter:
q = sess.query(IS).filter(IS.node == node).filter(IS.password == password).all()
或者直接用filter_by:
q = sess.query(IS).filter_by(node=node, password=password).all()
两者都对应sql:
SELECT tb_is.id AS tb_is_id, tb_is.node AS tb_is_node, tb_is.password AS tb_is_password, tb_is.email AS tb_is_email, tb_is.`admin` AS tb_is_admin, tb_is.contact AS tb_is_contact, tb_is.is_available AS tb_is_is_available, tb_is.is_url AS tb_is_is_url, tb_is.note AS tb_is_note
FROM tb_is
WHERE tb_is.password = %(password_1)s AND tb_is.node = %(node_1)s
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