Do not send readonly=1 when connection is already in readonly mode (this causes a database error)

src/infi/clickhouse_orm/database.py

@@ -26,8 +26,11 @@ class Database(object):
         self.db_url = db_url
         self.username = username
         self.password = password
-        self.readonly = readonly
-        if not self.readonly:
+        self.readonly = False
+        if readonly:
+            self.connection_readonly = self._is_connection_readonly()
+            self.readonly = True
+        else:
             self.create_database()
         self.server_timezone = self._get_server_timezone()
 
@@ -175,7 +178,8 @@ class Database(object):
             params['user'] = self.username
         if self.password:
             params['password'] = self.password
-        if self.readonly:
+        # Send the readonly flag, unless the connection is already readonly (to prevent db error)
+        if self.readonly and not self.connection_readonly:
             params['readonly'] = '1'
         return params
 
@@ -197,3 +201,7 @@ class Database(object):
         except DatabaseException:
             logger.exception('Cannot determine server timezone, assuming UTC')
             return pytz.utc
+
+    def _is_connection_readonly(self):
+        r = self._send("SELECT value FROM system.settings WHERE name = 'readonly'")
+        return r.text.strip() != '0'

tests/test_readonly.py

@@ -11,17 +11,32 @@ from .base_test_with_data import *
 
 class ReadonlyTestCase(TestCaseWithData):
 
-    def test_readonly(self):
+    def _test_readonly_db(self, username):
+        self._insert_and_check(self._sample_data(), len(data))
         orig_database = self.database
-        self.database = Database(orig_database.db_name, readonly=True)
-        with self.assertRaises(DatabaseException):
-            self._insert_and_check(self._sample_data(), len(data))
-        self.assertEquals(self.database.count(Person), 0)
-        with self.assertRaises(DatabaseException):
-            self.database.drop_table(Person)
-        with self.assertRaises(DatabaseException):
-            self.database.drop_database()
-        self.database = orig_database
+        try:
+            self.database = Database(orig_database.db_name, username=username, readonly=True)
+            with self.assertRaises(DatabaseException):
+                self._insert_and_check(self._sample_data(), len(data))
+            self.assertEquals(self.database.count(Person), 100)
+            list(self.database.select('SELECT * from $table', Person))
+            with self.assertRaises(DatabaseException):
+                self.database.drop_table(Person)
+            with self.assertRaises(DatabaseException):
+                self.database.drop_database()
+        except DatabaseException, e:
+            if 'Unknown user' in unicode(e):
+                raise unittest.SkipTest('Database user "%s" is not defined' % username)
+            else:
+                raise
+        finally:
+            self.database = orig_database
+
+    def test_readonly_db_with_default_user(self):
+        self._test_readonly_db('default')
+
+    def test_readonly_db_with_readonly_user(self):
+        self._test_readonly_db('readonly')
 
     def test_insert_readonly(self):
         m = ReadOnlyModel(name='readonly')