From 16125327b190e6a739b4431c567836bd2b4fc89a Mon Sep 17 00:00:00 2001
From: Arik Fraimovich <arik@arikfr.com>
Date: Tue, 13 May 2014 18:16:30 +0300
Subject: [PATCH] Class for SQL metadata logic (tables, ddl, dml statements)

---
 redash/utils.py             | 64 +++++++++++++++++++++++++++++--------
 tests/test_sql_meta_data.py | 28 ++++++++++++++++
 2 files changed, 79 insertions(+), 13 deletions(-)
 create mode 100644 tests/test_sql_meta_data.py

diff --git a/redash/utils.py b/redash/utils.py
index 7a9f0d44..9786331d 100644
--- a/redash/utils.py
+++ b/redash/utils.py
@@ -10,19 +10,57 @@ import sqlparse
 
 COMMENTS_REGEX = re.compile("/\*.*?\*/")
 
-def extract_table_names(tokens):
-    tables = set()
-    tokens = [t for t in tokens if t.ttype not in (sqlparse.tokens.Whitespace, sqlparse.tokens.Newline)]
-    
-    for i in range(len(tokens)):
-        if tokens[i].is_group():
-            tables.update(extract_table_names(tokens[i].tokens))
-        else:
-            if tokens[i].ttype == sqlparse.tokens.Keyword \
-            and tokens[i].normalized in ['FROM', 'JOIN', 'LEFT JOIN', 'FULL JOIN', 'RIGHT JOIN', 'CROSS JOIN', 'INNER JOIN', 'OUTER JOIN', 'LEFT OUTER JOIN', 'RIGHT OUTER JOIN', 'FULL OUTER JOIN'] \
-            and isinstance(tokens[i + 1], sqlparse.sql.Identifier):
-                tables.add(tokens[i + 1].value)
-    return tables
+
+class SQLMetaData(object):
+    TABLE_SELECTION_KEYWORDS = ('FROM', 'JOIN', 'LEFT JOIN', 'FULL JOIN', 'RIGHT JOIN', 'CROSS JOIN', 'INNER JOIN',
+                                'OUTER JOIN', 'LEFT OUTER JOIN', 'RIGHT OUTER JOIN', 'FULL OUTER JOIN')
+
+    def __init__(self, sql):
+        self.sql = sql
+        self.parsed_sql = sqlparse.parse(self.sql)
+
+        self.has_ddl_statements = self._find_ddl_statements()
+        self.has_non_select_dml_statements = self._find_dml_statements()
+        self.used_tables = self._find_tables()
+
+    def _find_ddl_statements(self):
+        for statement in self.parsed_sql:
+            if len([x for x in statement.flatten() if x.ttype == sqlparse.tokens.DDL]):
+                return True
+
+        return False
+
+    def _find_tables(self):
+        tables = set()
+        for statement in self.parsed_sql:
+            tables.update(self.extract_table_names(statement.tokens))
+
+        return tables
+
+    def extract_table_names(self, tokens):
+        tables = set()
+        tokens = [t for t in tokens if t.ttype not in (sqlparse.tokens.Whitespace, sqlparse.tokens.Newline)]
+
+        for i in range(len(tokens)):
+            if tokens[i].is_group():
+                tables.update(self.extract_table_names(tokens[i].tokens))
+            else:
+                if tokens[i].ttype == sqlparse.tokens.Keyword and tokens[i].normalized in self.TABLE_SELECTION_KEYWORDS:
+                    if isinstance(tokens[i + 1], sqlparse.sql.Identifier):
+                        tables.add(tokens[i + 1].value)
+
+                    if isinstance(tokens[i + 1], sqlparse.sql.IdentifierList):
+                        tables.update(set([t.value for t in tokens[i+1].get_identifiers()]))
+        return tables
+
+    def _find_dml_statements(self):
+        for statement in self.parsed_sql:
+            for token in statement.flatten():
+                if token.ttype == sqlparse.tokens.DML and token.normalized != 'SELECT':
+                    return True
+
+        return False
+
 
 def gen_query_hash(sql):
     """Returns hash of the given query after stripping all comments, line breaks and multiple
diff --git a/tests/test_sql_meta_data.py b/tests/test_sql_meta_data.py
new file mode 100644
index 00000000..68dc40da
--- /dev/null
+++ b/tests/test_sql_meta_data.py
@@ -0,0 +1,28 @@
+from redash.utils import SQLMetaData
+from unittest import TestCase
+
+
+class TestSQLMetaData(TestCase):
+    def test_simple_select(self):
+        metadata = SQLMetaData("SELECT t FROM test")
+        self.assertEquals(metadata.used_tables, set(("test",)))
+        self.assertFalse(metadata.has_ddl_statements)
+        self.assertFalse(metadata.has_non_select_dml_statements)
+
+    def test_multiple_select(self):
+        metadata = SQLMetaData("SELECT t FROM test, test2 WHERE t > 1; SELECT a, b, c FROM testing as tbl")
+        self.assertEquals(metadata.used_tables, set(("test", "test2", "testing")))
+        self.assertFalse(metadata.has_ddl_statements)
+        self.assertFalse(metadata.has_non_select_dml_statements)
+
+    def test_detects_ddl(self):
+        metadata = SQLMetaData("SELECT t FROM test; DROP TABLE test")
+        self.assertEquals(metadata.used_tables, set(("test",)))
+        self.assertTrue(metadata.has_ddl_statements)
+        self.assertFalse(metadata.has_non_select_dml_statements)
+
+    def test_detects_dml(self):
+        metadata = SQLMetaData("SELECT t FROM test; DELETE * FROM test")
+        self.assertEquals(metadata.used_tables, set(("test",)))
+        self.assertFalse(metadata.has_ddl_statements)
+        self.assertTrue(metadata.has_non_select_dml_statements)