Fix handling of JSON in the Query Tool with NULL elements. Fixes #4263

docs/en_US/release_notes_4_7.rst

@@ -24,6 +24,7 @@ Bug fixes
 | `Bug #4246 <https://redmine.postgresql.org/issues/4246>`_ - Fixed console error when subnode control is used in panels.
 | `Bug #4261 <https://redmine.postgresql.org/issues/4261>`_ - Stop using application/x-javascript as a mime type and use the RFC-compliant application/javascript instead.
 | `Bug #4262 <https://redmine.postgresql.org/issues/4262>`_ - Fixed error on displaying table properties of a table partitioned by list having a default partition.
+| `Bug #4263 <https://redmine.postgresql.org/issues/4263>`_ - Fix handling of JSON in the Query Tool with NULL elements.
 | `Bug #4269 <https://redmine.postgresql.org/issues/4269>`_ - Fix navigation of switch cells in grids.
 | `Bug #4275 <https://redmine.postgresql.org/issues/4275>`_ - Clarify wording for the NO INHERIT option on constraints, per Michel Feinstein.
 | `Bug #4276 <https://redmine.postgresql.org/issues/4276>`_ - Relax the permission check on the directory containing the config database, as it may fail in some environments such as OpenShift.

web/pgadmin/tools/sqleditor/static/js/sqleditor.js

@@ -2424,7 +2424,7 @@ define('tools.querytool', [
 
             if(data.types[0] && data.types[0].typname === 'json') {
               /* json is sent as text, parse it */
-              explain_data_json = JSON.parse(data.result[0]);
+              explain_data_json = JSON.parse(data.result[0][0]);
             }
 
             if (explain_data_json && explain_data_json[0] &&

web/pgadmin/tools/sqleditor/tests/test_explain_plan.py

@@ -0,0 +1,72 @@
+##########################################################################
+#
+# pgAdmin 4 - PostgreSQL Tools
+#
+# Copyright (C) 2013 - 2019, The pgAdmin Development Team
+# This software is released under the PostgreSQL Licence
+#
+##########################################################################
+
+import json
+
+from pgadmin.browser.server_groups.servers.databases.tests import utils as \
+    database_utils
+from pgadmin.utils.route import BaseTestGenerator
+from regression import parent_node_dict
+from regression.python_test_utils import test_utils as utils
+
+
+class TestExplainPlan(BaseTestGenerator):
+    """ This class will test the explain plan return format. """
+
+    def runTest(self):
+        database_info = parent_node_dict["database"][-1]
+        self.server_id = database_info["server_id"]
+
+        self.db_id = database_info["db_id"]
+        db_con = database_utils.connect_database(self,
+                                                 utils.SERVER_GROUP,
+                                                 self.server_id,
+                                                 self.db_id)
+        if not db_con["info"] == "Database connected.":
+            raise Exception("Could not connect to the database.")
+
+        # Initialize query tool
+        url = '/datagrid/initialize/query_tool/{0}/{1}/{2}'.format(
+            utils.SERVER_GROUP, self.server_id, self.db_id)
+        response = self.tester.post(url)
+        self.assertEquals(response.status_code, 200)
+
+        response_data = json.loads(response.data.decode('utf-8'))
+        self.trans_id = response_data['data']['gridTransId']
+
+        # Start query tool transaction
+        url = '/sqleditor/query_tool/start/{0}'.format(self.trans_id)
+        response = self.tester.post(
+            url, data=json.dumps({
+                "sql": "SELECT 1",
+                "explain_plan": {
+                    "format": "json",
+                    "analyze": False,
+                    "verbose": False,
+                    "costs": False,
+                    "buffers": False,
+                    "timing": False,
+                    "verbose": False
+                }
+            }), content_type='html/json')
+
+        self.assertEquals(response.status_code, 200)
+
+        # Query tool polling
+        url = '/sqleditor/poll/{0}'.format(self.trans_id)
+        response = self.tester.get(url)
+        self.assertEquals(response.status_code, 200)
+        response_data = json.loads(response.data.decode('utf-8'))
+
+        # Check the ouput of explain plan
+        self.assertEquals(len(response_data['data']['result']), 1)
+        self.assertEquals(len(response_data['data']['result'][0]), 1)
+
+        # Disconnect the database
+        database_utils.disconnect_database(self, self.server_id, self.db_id)