基于另一个表中的值的简单 SQLAlchemy 更新表

Question

I am a newcomer to SQLAlchemy, so please forgive what must be an elementary question.

I have a database table properties (mapped in SQLALchemy as the object Property ) which contains a field MEBID . I have another table mebs (mapped in SQLAlchemy as MEB ). I want to set the properties.MEBID field to mebs.id where properties.PostCode == mebs.PostCode.

I can do this simply in SQL using the command

update properties, mebs set properties.mebid = mebs.id where mebs.PostCode = properties.PostCode

but am struggling with doing it in SQLAlchemy. If I try the command

session.query(Property, MEB).\
  filter(Property.PostCode == MEB.PostCode).\
  update({Property.MEBID : MEB.id})

I get

InvalidRequestError: This operation requires only one Table or entity be specified as the target.

I know that this must be elementary as it's such a fundamental operation, but can't work out how it's done.

Answer 1

To update:

for prop, meb in session.query(Property, MEB).filter(Property.PostCode == MEB.PostCode).all():
    prop.MEBID=meb.id 
    session.add(prop)