Extend Book.getLanguageBook

lib/models/book.js

@@ -176,14 +176,18 @@ Book.prototype.isLanguageBook = function() {
 };
 
 /**
-    Return a languages book
+    Returns the book for a language.
+    Returns itself if matches the language itself.
 
-    @param {String} language
-    @return {Book}
+    @param {String} lang Language ID
+    @return {Book | Null} Null if no such language
 */
-Book.prototype.getLanguageBook = function(language) {
-    var books = this.getBooks();
-    return books.get(language);
+Book.prototype.getLanguageBook = function(lang) {
+    if (this.getLanguage() === lang) {
+        return this;
+    } else {
+        return this.getBooks().get(lang) || null;
+    }
 };
 
 /**