SQLAlchemy中filter()和filter_by()有什么區別

from:https://segmentfault.com/q/1010000000140472

filter:

apply the given filtering criterion to a copy of this Query, using SQL expressions.
e.g.:
session.query(MyClass).filter(MyClass.name == 'some name')

filter_by:

apply the given filtering criterion to a copy of this Query, using keyword expressions.
e.g.:
session.query(MyClass).filter_by(name = 'some name')

確實，filter用類名.屬性名，比較用==，filter_by直接用屬性名，比較用=
不過這個是語法小細節。

個人覺得最重要的區別是filter不支持組合查詢，只能連續調用filter來變相實現。
而filter_by的參數是**kwargs，直接支持組合查詢。
比如：

q = sess.query(IS).filter(IS.node == node and IS.password == password).all()
對應的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)s

and后面的條件既不報錯，又不生效，很坑。

要實現組合查詢，要么連續調用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()

兩者都對應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