Fix empty external tables sending #240

mymarilyn · Aug 19, 2021 · 78e389e · 78e389e
1 parent 10103f8
commit 78e389e
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Showing 3 changed files with 28 additions and 0 deletions.
diff --git a/clickhouse_driver/block.py b/clickhouse_driver/block.py
@@ -132,6 +132,9 @@ def normalize(self, data):
 
     @property
     def num_columns(self):
+        if self.columns_with_types is not None:
+            return len(self.columns_with_types)
+
         return len(self.data[0]) if self.num_rows else 0
 
     @property

diff --git a/clickhouse_driver/connection.py b/clickhouse_driver/connection.py
@@ -609,6 +609,11 @@ def send_cancel(self):
 
     def send_external_tables(self, tables, types_check=False):
         for table in tables or []:
+            if not table['structure']:
+                raise ValueError(
+                    'Empty table "{}" structure'.format(table['name'])
+                )
+
             block = RowOrientedBlock(table['structure'], table['data'],
                                      types_check=types_check)
             self.send_data(block, table_name=table['name'])

diff --git a/tests/test_external_tables.py b/tests/test_external_tables.py
@@ -14,3 +14,23 @@ def test_select(self):
         }]
         rv = self.client.execute('SELECT * FROM test', external_tables=tables)
         self.assertEqual(rv, [(100, [2, 4, 6, 8]), (500, [1, 3, 5, 7])])
+
+    def test_send_empty_table(self):
+        tables = [{
+            'name': 'test',
+            'structure': [('x', 'Int32')],
+            'data': []
+        }]
+        rv = self.client.execute('SELECT * FROM test', external_tables=tables)
+        self.assertEqual(rv, [])
+
+    def test_send_empty_table_structure(self):
+        tables = [{
+            'name': 'test',
+            'structure': [],
+            'data': []
+        }]
+        with self.assertRaises(ValueError) as e:
+            self.client.execute('SELECT * FROM test', external_tables=tables)
+
+        self.assertIn('Empty table "test" structure', str(e.exception))