def left_join(right, left, onclause):
"""
Function: Join columns using an inner join
Input:
1. Right statement/table to be joined,
2. Left statement/table to be joined,
3. A SQL expression representing the ON clause of the join. If left at None, it attempts to join the two tables based on a foreign key relationship
If more than 1 expression is listed, (expressions) have to use an '&' operator. Ex: (Table1.c.colname1 = Table2.c.colname1 & Table1.c.colname2 = Table2.c.colname2)
Output: A joined object
Example: Table1 >> to_statement >> left_join(Table2, onclause=(Table1.c.colname = Table2.c.colname):BooleanClauseList)
"""
left, right = left.alias(), table_check(right)
print(left, right)
l1, r1 = get_onclause_col(onclause)
l2, r2 = [c.name for c in l1], [c.name for c in r1]
l3, r3 = sorted([c for c in left.columns if c.name in l2],
key=lambda x: x.name), sorted(
[c for c in right.columns if c.name in r2],
key=lambda x: x.name)
col_dict = dict(zip(l3, r3))
expr_list = [(k == v) for k, v in col_dict.items()]
clause = reduce(lambda x, y: operator.iand(x, y), expr_list)
return select_sql([left.join_sql(right, onclause=clause, isouter=True)])
def maybe_wrap(stmt):
if isinstance(stmt, Alias):
return select_sql([col for col in stmt.c]).select_from(stmt)
else:
return stmt
def _maybe_wrap(stmt):
if isinstance(stmt, Alias):
return select_sql(everything(stmt)).select_from(stmt)
else:
return stmt
def to_statement(table_class):
"""Returns all columns from a table as a 'Select' object"""
return select_sql(everything(table_class))
def to_statement(table_class):
return select_sql(everything(table_class))