Clear sqlalchemy reflection cache

Question

I'm using sqlalchemy's reflection tools to get a Table object. I do this because these tables are dynamic and tables/columns can change. Here's the code I'm using:

def getTableByReflection(self, tableName, metadata, engine):

    return Table(tableName, metadata, autoload = True, autoload_with = engine)

The problem is that when the above code is run twice it seems to return the same results regardless of whether or not the columns have changed. I have tried refreshing using the mysession.refresh(mytable) but that fails because the table is not attached to any metadata - which makes sense but then why am I seeing cached results?

Is there any way to tell the metadata/engine/session to forget about this table and let me load it cleanly?

Answer 1

传入新创建的新元数据实例。

Answer 2

With thanks to codeape 's comment above I was able to fix the problem by changing the syntax to:

def getTableByReflection(self, tableName, metadata, engine):

    return Table(tableName, MetaData(), autoload = True, autoload_with = engine)

So passing in a new MetaData() instance each time. This probably affects performance but it's ok for me in this part of my app.

All credit to codeape