final, ok for indirect recursion too .
##########
import sqlalchemy
def join_via( keys, mapper):
'''Query.join_via, input root mapper, return last mapper/table;
alias and link properly recursive /self-referential joins
'''
clause = None
c = None
self_table = None
self_colequivalents = None
xmappers = [mapper] #mapper === parent
for key in keys:
prop = mapper.props[key]
c = prop.get_join( mapper) #SA rev>=2285
parent_table = self_table
self_table = prop.target
parent_colequivalents = self_colequivalents
self_colequivalents =
prop.mapper._get_inherited_column_equivalents()
print key,prop.primaryjoin,prop.foreignkey,prop.remote_side
if prop.mapper in xmappers:
self_table = self_table.alias()
print '>>', self_table.name
c.accept_visitor( sqlalchemy.sql_util.ClauseAdapter(
self_table, include=prop.remote_side,
equivalents= self_colequivalents
))
xmappers.append( prop.mapper)
if mapper in xmappers:
if parent_table:
c.accept_visitor( sqlalchemy.sql_util.ClauseAdapter(
parent_table, include=prop.foreignkey,
equivalents= parent_colequivalents
))
print '>>>', c
if clause is None:
clause = c
else:
clause &= c
mapper = prop.mapper
return clause, mapper, self_table
##########
Anyone interested in the resulting expression-translator?
It is independent from the sawrap-per, although will be used inside.
e.g. convert plain python-func/method
def myfilter( person):
return ( (person.friend.address.owner.friend.age > 20)
& person.name.startswith('a') )
into SA-query...
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