if you can provide an example of the specific operation you're doing I can evaluate if this might be impacting SQLAlchemy internally or otherwise what this use case is.
On Wed, May 9, 2018 at 1:15 PM, Zac Goldstein <[email protected]> wrote: > Thanks for the pointers and for checking. I misidentified the problem in > traverse. It does eventually iterate down to just the columns in the call > to _copy_internals. So the problem boils down to the second thing I > mentioned which is the require_embedded parameter being set to true when > corresponding_column is called. The selectable I'm using isn't just a > simple alias. > > I subclassed ClauseAdapter and rewrote replace so that corresponding_column > is called with require_embedded=False > (https://github.com/zzzeek/sqlalchemy/blob/699272e4dcb9aa71ebbc0d9487fb6de82d3abc2b/lib/sqlalchemy/sql/util.py#L656). > This seems to be working. > > > On Wednesday, May 9, 2018 at 12:28:28 AM UTC-7, Zac Goldstein wrote: >> >> I'm trying to use ClauseAdapter.traverse similar to how it's used in your >> old blog post to substitute columns in arbitrary clauses with columns on a >> different selectable that share an ancestor: >> http://techspot.zzzeek.org/archive/2008/01/1/ >> >> Even in a simple case using a BinaryExpression, >> ClauseAdapter(selectable).traverse(binaryexpression) is simply returning the >> expression. When I looked at it with the debugger, it seems the expression >> isn't being traversed, but rather it eventually feeds the entire >> BinaryExpression object into corresponding_column and subsequently returns >> the full expression since obviously the BinaryExpression can't be matched to >> a particular column on the selectable. >> >> selectable.corresponding_column(binaryexpression.left) returns the correct >> column, however ClauseAdapter(selectable).traverse(binaryexpression.left) >> does not. The discrepancy is found in corresponding_column being called >> with require_embedded=True during traverse, which is hardcoded. I don't >> know if this behavior causes the behavior I previously described with the >> BinaryExpression being passed to corresponding_column, but it seemed >> noteworthy. >> >> Any ideas for fixes or alternatives? >> >> Thanks >> >> >> > -- > SQLAlchemy - > The Python SQL Toolkit and Object Relational Mapper > > http://www.sqlalchemy.org/ > > To post example code, please provide an MCVE: Minimal, Complete, and > Verifiable Example. See http://stackoverflow.com/help/mcve for a full > description. > --- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/d/optout. -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
