Added save-again-to-same-file feature, with tests

Author: nathancarter

cloud-storage.js

@@ -172,6 +172,11 @@ function failureDebug () {
  * If the user doesn't log in to the service or cancels the dialog, the
  * failure callback will be called.
  *
+ * The object passed to the success callback also contains an `update`
+ * member, which can be used to save new content over top of the content of
+ * the file opened using this method.  See details in the `saveFile`
+ * function implemented, after the `openFile` function, further below.
+ *
  * By default, this routine displays an iframe to contain the File > Open
  * dialog it shows to the user.  If the client already has an iframe to use
  * as the dialog, it can be passed as the third parameter, and will be used.
@@ -212,6 +217,12 @@ openFile = window.openFile = function ( successCB, failureCB, iframe )
                             if ( !succ ) succ = successDebug;
                             if ( !fail ) fail = failureDebug;
                             fileSystemBackEnd.readFile( path, succ, fail );
+                        },
+                        update : function ( content, succ, fail ) {
+                            if ( !succ ) succ = successDebug;
+                            if ( !fail ) fail = failureDebug;
+                            fileSystemBackEnd.writeFile( path, content,
+                                succ, fail );
                         }
                     } );
                 } else {
@@ -229,13 +240,6 @@ openFile = window.openFile = function ( successCB, failureCB, iframe )
     } );
 }
 
-/*
- * Failure callback will have reason as a string parameter.
- * Success callback will have an object with file metadata, and a method
- * for resaving the file, update(newContent,successCB,failureCB), in which
- * the first callback will yield a new object to replace the old, and the
- * second will have an error message.
- */
 /*
  * Show a "File > Save" dialog box.
  *

test.html

@@ -41,6 +41,8 @@
                    onclick='testOpenFile();'/>
             <input type='button' value='Test saving a file'
                    onclick='testSaveFile();'/>
+            <input type='button' value='Test re-saving the same file'
+                   onclick='testResaveFile();'/>
         </p>
 
         <!--
@@ -138,11 +140,16 @@
                 return ( dialog.style.display == 'block' ) ? dialog : null;
             }
 
+            // Global variable used to store the last result of a success
+            // callback from any of the functions below.  Necessary to
+            // implement the "re-save the same file" feature.
+            var lastFileObject = null;
             // Event handler when the user clicks "Test opening a file."
             // In the various success and failure callbacks, populate one or
             // both of the two textareas with the results.
             function testOpenFile () {
                 openFile( function ( chosenFile ) {
+                    lastFileObject = chosenFile;
                     chosenFile.get( function ( content ) {
                         setMessages( 'User chose: ' + chosenFile.path, null,
                                      'File loaded successfully' );
@@ -154,6 +161,7 @@
                         if ( dialogIfVisible() ) toggleDialog();
                     } );
                 }, function ( error ) {
+                    lastFileObject = null;
                     setMessages( null, 'Error', error );
                     if ( dialogIfVisible() ) toggleDialog();
                 }, dialogIfVisible() );
@@ -163,6 +171,7 @@
             // both of the two textareas with the results.
             function testSaveFile () {
                 saveFile( function ( destination ) {
+                    lastFileObject = destination;
                     destination.update( getEditor(), function ( result ) {
                         setMessages( 'Destination: ' + destination.path,
                                      'Success', result );
@@ -173,10 +182,36 @@
                         if ( dialogIfVisible() ) toggleDialog();
                     } );
                 }, function ( error ) {
+                    lastFileObject = null;
                     setMessages( null, 'Error', error );
                     if ( dialogIfVisible() ) toggleDialog();
                 }, dialogIfVisible() );
             }
+            // Event handler when the user clicks "Test re-saving the same
+            // file."  In the various success and failure callbacks,
+            // populate one or both of the two textareas with the results.
+            function testResaveFile () {
+                if ( !lastFileObject ) {
+                    setMessages( null, 'Error',
+                        'You have not yet successfully opened or saved a '
+                      + ' file, and so you cannot re-save to the "same" '
+                      + ' location.' );
+                } else {
+                    lastFileObject.update( getEditor(),
+                        function ( result ) {
+                            setMessages( 'Destination: '
+                                       + lastFileObject.path,
+                                         'Success', result );
+                            if ( dialogIfVisible() ) toggleDialog();
+                        }, function ( error ) {
+                            setMessages( 'Destination: '
+                                       + lastFileObject.path,
+                                         'Error', error );
+                            if ( dialogIfVisible() ) toggleDialog();
+                        }
+                    );
+                }
+            }
         </script>
     </body>
 </html>