[feat] Throw when trying to save a fetched file.

Author: leeyeh

lib/file.js

@@ -571,6 +571,9 @@ module.exports = function(AV) {
      * @return {AV.Promise} Promise that is resolved when the save finishes.
      */
     save: function() {
+      if (this.id) {
+        throw new Error('File already saved. If you want to manipulate a file, use AV.Query to get it.');
+      }
       var options = null;
       var saveOptions = {};
       if(arguments.length === 1) {
@@ -637,6 +640,16 @@ module.exports = function(AV) {
       return self._previousSave._thenRunCallbacks(options);
     },
 
+    /**
+    * fetch the file from server. If the server's representation of the
+    * model differs from its current attributes, they will be overriden,
+    * @param {Object} fetchOptions Optional options to set 'keys' and
+    *      'include' option.
+    * @param {Object} options Optional Backbone-like options object to be
+    *     passed in to set.
+    * @return {AV.Promise} A promise that is fulfilled when the fetch
+    *     completes.
+    */
     fetch: function() {
         var options = null;
         var fetchOptions = {};
@@ -650,8 +663,8 @@ module.exports = function(AV) {
         var self = this;
         var request = AV._request('files', null, this.id, 'GET',
                                   fetchOptions);
-        return request.then(function(response, status, xhr) {
-          var value = AV.Object.prototype.parse(response, status, xhr);
+        return request.then(function(response) {
+          var value = AV.Object.prototype.parse(response);
           value._metaData = value.metaData || {};
           value._url = value.url;
           value._name = value.name;

test/file.js

@@ -178,6 +178,12 @@ describe("files", function() {
       expect(file).to.be.a(AV.File);
       expect(file.id).to.be(fileId);
     });
+    it('save a fetched file should throw', function(){
+      var file = AV.File.createWithoutData(fileId);
+      expect(function saveFetchedFile(){
+        file.save();
+      }).to.throwError(/File already saved\./);
+    });
     it('fetch() should retrieve all data', function(done){
       var file = AV.File.createWithoutData(fileId);
       file.fetch().then(function(file){