feat(core): add isLocalized method to LocalizationService

#3791

npm/ng-packs/packages/core/src/lib/services/localization.service.ts

@@ -1,11 +1,12 @@
 import { Injectable, NgZone, Optional, SkipSelf } from '@angular/core';
 import { ActivatedRouteSnapshot, Router } from '@angular/router';
-import { Store, Actions, ofActionSuccessful } from '@ngxs/store';
+import { Actions, ofActionSuccessful, Store } from '@ngxs/store';
 import { noop, Observable } from 'rxjs';
+import { SetLanguage } from '../actions/session.actions';
+import { ApplicationConfiguration } from '../models/application-configuration';
+import { Config } from '../models/config';
 import { ConfigState } from '../states/config.state';
 import { registerLocale } from '../utils/initial-utils';
-import { Config } from '../models/config';
-import { SetLanguage } from '../actions/session.actions';
 
 type ShouldReuseRoute = (future: ActivatedRouteSnapshot, curr: ActivatedRouteSnapshot) => boolean;
 
@@ -75,4 +76,31 @@ export class LocalizationService {
   instant(key: string | Config.LocalizationWithDefault, ...interpolateParams: string[]): string {
     return this.store.selectSnapshot(ConfigState.getLocalization(key, ...interpolateParams));
   }
+
+  isLocalized(key, sourceName) {
+    if (sourceName === '_') {
+      //A convention to suppress the localization
+      return true;
+    }
+
+    const localization = this.store.selectSnapshot(
+      ConfigState.getOne('localization'),
+    ) as ApplicationConfiguration.Localization;
+    sourceName = sourceName || localization.defaultResourceName;
+    if (!sourceName) {
+      return false;
+    }
+
+    const source = localization.values[sourceName];
+    if (!source) {
+      return false;
+    }
+
+    const value = source[key];
+    if (value === undefined) {
+      return false;
+    }
+
+    return true;
+  }
 }