[fix] disable email alert on wrong field. fixes frappe/erpnext#3372 (#3290)

frappe/email/doctype/email_alert/email_alert.py

@@ -217,7 +217,14 @@ def evaluate_alert(doc, alert, event):
 				return
 
 		if event=="Value Change" and not doc.is_new():
-			db_value = frappe.db.get_value(doc.doctype, doc.name, alert.value_changed)
+			try:
+				db_value = frappe.db.get_value(doc.doctype, doc.name, alert.value_changed)
+			except frappe.DatabaseOperationalError as e:
+				if e.args[0]==1054:
+					alert.db_set('enabled', 0)
+					frappe.log_error('Email Alert {0} has been disabled due to missing field'.format(alert.name))
+					return
+
 			db_value = parse_val(db_value)
 			if (doc.get(alert.value_changed) == db_value) or \
 				(not db_value and not doc.get(alert.value_changed)):

frappe/email/doctype/email_alert/test_email_alert.py

@@ -87,6 +87,36 @@ class TestEmailAlert(unittest.TestCase):
 		self.assertTrue(frappe.db.get_value("Email Queue", {"reference_doctype": "Event",
 			"reference_name": event.name, "status":"Not Sent"}))
 
+	def test_alert_disabled_on_wrong_field(self):
+		frappe.set_user('Administrator')
+		email_alert = frappe.get_doc({
+			"doctype": "Email Alert",
+			"subject":"_Test Email Alert for wrong field",
+			"document_type": "Event",
+			"event": "Value Change",
+			"attach_print": 0,
+			"value_changed": "description1",
+			"message": "Description changed",
+			"recipients": [
+				{ "email_by_document_field": "owner" }
+			]
+		}).insert()
+
+		event = frappe.new_doc("Event")
+		event.subject = "test-2",
+		event.event_type = "Private"
+		event.starts_on  = "2014-06-06 12:00:00"
+		event.insert()
+		event.subject = "test 1"
+		event.save()
+
+		# verify that email_alert is disabled
+		email_alert.reload()
+		self.assertEqual(email_alert.enabled, 0)
+		email_alert.delete()
+		event.delete()
+
+
 	def test_date_changed(self):
 		event = frappe.new_doc("Event")
 		event.subject = "test",

frappe/exceptions.py

@@ -7,6 +7,7 @@ from __future__ import unicode_literals
 
 from werkzeug.exceptions import NotFound
 from MySQLdb import ProgrammingError as SQLError, Error
+from MySQLdb import OperationalError as DatabaseOperationalError
 
 
 class ValidationError(Exception):