Add JSON access query support

Author: Ricardo Piro-Rael

base.py

@@ -288,6 +288,12 @@ def visit_external_stage(self, external_stage, **kw):
                                                     external_stage.path,
                                                     external_stage.file_format)
 
+    def visit_json_getitem_op_binary(self, binary, operator, **kw):
+        return '%s[%s]' % (
+            self.process(binary.left, **kw),
+            self.process(binary.right, **kw)
+        )
+
     def delete_extra_from_clause(self, delete_stmt, from_table,
                                  extra_froms, from_hints, **kw):
         return "USING " + ', '.join(

test/test_compiler.py

@@ -1,15 +1,16 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-from sqlalchemy import Integer, String, and_, select
+from sqlalchemy import Integer, JSON, String, and_, select
 from sqlalchemy.sql import column, quoted_name, table
 from sqlalchemy.testing import AssertsCompiledSQL
 
 table1 = table(
     'table1',
     column('id', Integer),
     column('name', String),
-    column('value', Integer)
+    column('value', Integer),
+    column('metadata', JSON)
 )
 
 table2 = table(
@@ -19,7 +20,6 @@
     column('value', Integer)
 )
 
-
 class TestSnowflakeCompiler(AssertsCompiledSQL):
     __dialect__ = "snowflake"
 
@@ -55,6 +55,16 @@ def test_multi_table_update(self):
         )
 
 
+    def test_json_getitem(self):
+        statement = table1.query \
+            .with_entities(table1.metadata['size'].label('size')) \
+            .statement
+        self.assert_compile(
+            statement,
+            "SELECT data['size'] AS size FROM table1"
+        )
+
+
 def test_quoted_name_label(engine_testaccount):
     test_cases = [
         # quote name