feat(translation): Translate pipe

ionic/ionic.ts

@@ -26,3 +26,4 @@ export * from './transitions/md-transition'
 export * from './platform/plugins'
 
 export * from './translation/translate'
+export * from './translation/translate_pipe'

ionic/translation/translate.ts

@@ -18,22 +18,18 @@ export class Translate {
     return this._transMap[lang];
   }
 
-  translate(lang, key) {
-    // If called with just one param, first is the key
-    if(typeof key === 'undefined') {
-      key = lang;
-      lang = this._language;
-    }
-
-    // If the language isn't specified, return the string passed.
-    if(!lang) {
+  translate(key, lang) {
+    // If the language isn't specified and we have no overridden one, return the string passed.
+    if(!lang && !this._language) {
       return key;
     }
 
-    let map = this.getTranslations(lang);
+    let setLanguage = lang || this._language;
+
+    let map = this.getTranslations(setLanguage);
 
     if(!map) {
-      console.warn('I18N: No translation for key', key, 'using language', this._language);
+      console.warn('I18N: No translation for key', key, 'using language', setLanguage);
       return '';
     }
     return this._getTranslation(map, key);

ionic/translation/translate_pipe.ts

@@ -0,0 +1,30 @@
+import {Injectable, Pipe, PipeTransform} from 'angular2/angular2';
+
+import {Translate} from './translate';
+
+/**
+ * The Translate pipe makes it easy to translate strings.
+ *
+ * @usage
+ * Translate using the current language or language set through Translate.setLanguage
+ * {{ 'Please enter your location' | translate }}
+ *
+ * Translate using a specific language
+ * {{ 'Please enter your location' | translate:"de" }}
+ */
+@Pipe({name: 'translate'})
+@Injectable()
+export class TranslatePipe implements PipeTransform {
+  constructor(translate: Translate) {
+    this.translate = translate;
+  }
+  transform(value, args) {
+    let lang;
+    if(args.length > 0) {
+      lang = args[0];
+    }
+    return this.translate.translate(value, lang);
+  }
+
+  supports(obj) { return true; }
+}