使用 SQLAlchemy，我可以在查询中加入 Python object（即列表）吗？

Question

Assuming I have a Postgres-DB table looking like this (with with many more rows):

|------|-------|
|col1  |col 2  |
|------|-------|
|a1    |10     |
|a2    |55     |
|a3    |24     |
|------|-------|

And a List in Python with Tuples looking like this:

|------|-------|
|a1    |1      |
|a3    |2      |
|------|-------|

During runtime I now want to (inner) join the table with the list without having to persist the list as a DB object.

What does work, is to filter using the list and SQLAlchemys .in_ operator.

However when I try db.query(Table).join(list) I get this error:

sqlalchemy.exc.NoInspectionAvailable: No inspection system is available for object of type

Of course a workaround would be to first fetch all elements from the db using the filter operator and then using python for the join...but it feels like there should be a

Answer 1

If I understood correctly and you want to only get the rows where col1 == tuple[0] , you can use the sqlalchemy filter and in_ operators:

tuples_list = [('a1', 1), ('a3', 2)]

search_dict = dict(tuples_list)  # Convert to dict 

res = db.query(Table).filter(Table.col1.in_(search_dict.keys())).all()

for instance in res:
    instance.col2 = instance.col2 + search_dict[instance.col1]

There's also a detailed example without using the ORM here: SQLAlchemy IN clause