Use _extract_recursive_joins to handle multiple joins

src/suql/sql_free_text_support/execute_free_text_sql.py

@@ -619,7 +619,7 @@ def _retrieve_and_verify(
     elif len(node.fromClause) == 1 and isinstance(node.fromClause[0], JoinExpr):
         single_table = False
         id_list = {}
-        for arg in [node.fromClause[0].larg, node.fromClause[0].rarg]:
+        for arg in _extract_recursive_joins(node.fromClause[0]):
             if isinstance(arg, RangeVar):
                 table_name = arg.relname
                 id_field_name = table_w_ids[table_name]
@@ -1133,8 +1133,31 @@ def visit_ColumnRef(self, ancestors: Ancestor, node: ColumnRef):
                         # the same field appears twice, this means that the original syntax is problematic
                         break
                     res = (String(sval=f"{table_name}^{node.fields[0].sval}"),)
-            node.fields = res
+
+            # do not replace if None, b/c this should be an aliased field
+            if res is not None:
+                node.fields = res
 
+def _extract_recursive_joins(
+    fromClause: JoinExpr
+):
+    """
+    A FROM clause of a SelectStmt could have multiple joins.
+    This functions searilizes the joins and returns them as a list.
+    """
+    res = []
+    if isinstance(fromClause.larg, RangeVar):
+        res.append(fromClause.larg)
+    if isinstance(fromClause.rarg, RangeVar):
+        res.append(fromClause.rarg)
+
+    if isinstance(fromClause.larg, JoinExpr):
+        res.extend(_extract_recursive_joins(fromClause.larg))
+    if isinstance(fromClause.rarg, JoinExpr):
+        res.extend(_extract_recursive_joins(fromClause.rarg))
+
+    return res
+
 
 def _execute_structural_sql(
     original_node: SelectStmt,
@@ -1157,7 +1180,7 @@ def _execute_structural_sql(
     elif len(node.fromClause) == 1 and isinstance(node.fromClause[0], JoinExpr):
         all_projection_fields = []
         table_column_mapping = {}
-        for table in [node.fromClause[0].larg, node.fromClause[0].rarg]:
+        for table in _extract_recursive_joins(node.fromClause[0]):
             # find out what columns this table has
             _, columns = execute_sql_with_column_info(
                 RawStream()(SelectStmt(fromClause=(table,), targetList=(ResTarget(val=ColumnRef(fields=(A_Star(),))),))),
@@ -1189,6 +1212,8 @@ def _execute_structural_sql(
             table_column_mapping=table_column_mapping
         )
         replace_original_target_visitor(original_node.targetList)
+        if original_node.groupClause is not None:
+            replace_original_target_visitor(original_node.groupClause)
         if original_node.sortClause is not None:
             replace_original_target_visitor(original_node.sortClause)
     # next, there are tuple joins (self joins)
@@ -1234,8 +1259,10 @@ def _execute_structural_sql(
     node.limitOffset = None
     # change predicates
     node.whereClause = predicate
+    # reset other unecessary clauses
     node.groupClause = None
     node.havingClause = None
+    node.sortClause = None
 
     # only queries that involve only structural parts can be executed
     assert _if_all_structural(node)