well the good news is that these cloning bugs, which have the property that each time I spend four hours fixing one I'm absolutely convinced it's the last (a process which began at least four years ago), are my highest priority since there are usually zero workarounds and also indicate there's many other places that they can be occurring.
The call to s._from_obj.union(s._froms) regards keeping a set around of all the copies of from objects. At the end of the day a particular FROM can be in these sets any number of times as various clones of itself and is normal - the actual list of FROMs to be rendered always has a unique list. The issue here centers around Select._froms at line 4769. What happens here is a SELECT that contains a selectable Q, and a JOIN of Q to R, should be "hiding" the instance of Q by itself. But the "hiding" logic in this case isn't matching up the cloned join of Q to R to the Q by itself, so you get "Q, Q JOIN R" in the FROM clause. The point of _from_cloned is to keep track of all the copies of Q. anyway its ticket http://www.sqlalchemy.org/trac/ticket/2453, I'd like to get this out today but hopefully it won't be too hard. On Mar 30, 2012, at 6:50 AM, Christoph Rauch wrote: > Hello List, > > the problem I am facing is that _deep_deannotate, which is used in > ColumnProperty.__init__, breaks the FROM clause of my select() object if this > select() has a JOIN (either left or right, doesn't matter) as from_obj in it, > _where the initial table is aliased_. > > To illustrate I'll append my testcase. I traced it down to > Select._copy_internals(), line 4907 in sqlalchemy.sql.expression, where the > call to s._from_obj.union(s._froms) will happily add an the initial table _a > second time_ to the FROM clause, (it is already part of the join object) > resulting in an error from the database because the alias is duplicated in > the generated SQL. > > Taking any hints on how to fix this. :) > > Reproduced in 0.7.6 > > thanks, > Christoph > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/sqlalchemy/-/w1P2N5cbeL4J. > To post to this group, send email to sqlalchemy@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > <deep_deannotate_and_aliased_tables.py> -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
