Add support for RETURNING in SQLAlchemy dialect

Author: chaudum

src/crate/client/sqlalchemy/compiler.py

@@ -177,6 +177,13 @@ def visit_any(self, element, **kw):
             self.process(element.right, **kw)
         )
 
+    def returning_clause(self, stmt, returning_cols):
+        columns = [
+            self._label_select_column(None, c, True, False, {})
+            for c in sa.sql.expression._select_iterables(returning_cols)
+        ]
+        return "RETURNING " + ", ".join(columns)
+
     def visit_insert(self, insert_stmt, asfrom=False, **kw):
         """
         used to compile <sql.expression.Insert> expressions.

src/crate/client/sqlalchemy/dialect.py

@@ -165,6 +165,7 @@ class CrateDialect(default.DefaultDialect):
     type_compiler = CrateTypeCompiler
     supports_native_boolean = True
     colspecs = colspecs
+    implicit_returning = True
 
     def __init__(self, *args, **kwargs):
         super(CrateDialect, self).__init__(*args, **kwargs)