Extended AlertContextValue with metadata optional property

x-pack/plugins/triggers_actions_ui/public/application/components/builtin_alert_types/threshold/expression.tsx

@@ -143,7 +143,8 @@ export const IndexThresholdAlertTypeExpression: React.FunctionComponent<IndexThr
       groupBy: groupBy ?? DEFAULT_VALUES.GROUP_BY,
       threshold: threshold ?? DEFAULT_VALUES.THRESHOLD,
     });
-    if (index.length > 0) {
+
+    if (index && index.length > 0) {
       const currentEsFields = await getFields(index);
       const timeFields = getTimeFieldOptions(currentEsFields as any);
 

x-pack/plugins/triggers_actions_ui/public/application/context/alerts_context.tsx

@@ -23,6 +23,7 @@ export interface AlertsContextValue {
   >;
   charts?: ChartsPluginSetup;
   dataFieldsFormats?: DataPublicPluginSetup['fieldFormats'];
+  metadata?: Record<string, any>;
 }
 
 const AlertsContext = createContext<AlertsContextValue>(null as any);

x-pack/plugins/triggers_actions_ui/public/application/sections/alert_form/alert_add.test.tsx

@@ -6,18 +6,35 @@
 import * as React from 'react';
 import { mountWithIntl, nextTick } from 'test_utils/enzyme_helpers';
 import { act } from 'react-dom/test-utils';
+import { FormattedMessage } from '@kbn/i18n/react';
+import { EuiFormLabel } from '@elastic/eui';
 import { coreMock } from '../../../../../../../src/core/public/mocks';
 import { AlertAdd } from './alert_add';
 import { actionTypeRegistryMock } from '../../action_type_registry.mock';
 import { ValidationResult } from '../../../types';
-import { AlertsContextProvider } from '../../context/alerts_context';
+import { AlertsContextProvider, useAlertsContext } from '../../context/alerts_context';
 import { alertTypeRegistryMock } from '../../alert_type_registry.mock';
 import { chartPluginMock } from '../../../../../../../src/plugins/charts/public/mocks';
 import { dataPluginMock } from '../../../../../../../src/plugins/data/public/mocks';
 import { ReactWrapper } from 'enzyme';
 const actionTypeRegistry = actionTypeRegistryMock.create();
 const alertTypeRegistry = alertTypeRegistryMock.create();
 
+export const TestExpression: React.FunctionComponent<any> = () => {
+  const alertsContext = useAlertsContext();
+  const { metadata } = alertsContext;
+
+  return (
+    <EuiFormLabel>
+      <FormattedMessage
+        defaultMessage="Metadata: {val}. Fields: {fields}."
+        id="xpack.triggersActionsUI.sections.alertAdd.metadataTest"
+        values={{ val: metadata!.test, fields: metadata!.fields.join(' ') }}
+      />
+    </EuiFormLabel>
+  );
+};
+
 describe('alert_add', () => {
   let deps: any;
   let wrapper: ReactWrapper<any>;
@@ -41,7 +58,7 @@ describe('alert_add', () => {
       validate: (): ValidationResult => {
         return { errors: {} };
       },
-      alertParamsExpression: () => <React.Fragment />,
+      alertParamsExpression: TestExpression,
     };
 
     const actionTypeModel = {
@@ -77,13 +94,10 @@ describe('alert_add', () => {
           alertTypeRegistry: deps.alertTypeRegistry,
           toastNotifications: deps.toastNotifications,
           uiSettings: deps.uiSettings,
+          metadata: { test: 'some value', fields: ['test'] },
         }}
       >
-        <AlertAdd
-          consumer={'alerting'}
-          addFlyoutVisible={true}
-          setAddFlyoutVisibility={state => {}}
-        />
+        <AlertAdd consumer={'alerting'} addFlyoutVisible={true} setAddFlyoutVisibility={() => {}} />
       </AlertsContextProvider>
     );
     // Wait for active space to resolve before requesting the component to update
@@ -97,5 +111,10 @@ describe('alert_add', () => {
     await setup();
     expect(wrapper.find('[data-test-subj="addAlertFlyoutTitle"]').exists()).toBeTruthy();
     expect(wrapper.find('[data-test-subj="saveAlertButton"]').exists()).toBeTruthy();
+    wrapper
+      .find('[data-test-subj="my-alert-type-SelectOption"]')
+      .first()
+      .simulate('click');
+    expect(wrapper.contains('Metadata: some value. Fields: test.')).toBeTruthy();
   });
 });