Overview of API changes from 3.4.1

The architectural changes resulted in the deprecation, replacement, or removal of some of the attributes, properties, methods and events from 3.4.1 version of the Uploader. Here is a quick list of the changes most likely to affect your upgrade:

Attribute changes

Attribute in 3.4.1	Change in 3.5.0
buttonSkin	No longer exists. The Uploader in Flash mode is now always rendered as transparent, overlaying a "Select Files" button that can be replaced with any control (with any skin) using the selectFilesButton attribute.
fileFilters	Only available when the Uploader is in Flash mode, and has no effect when the Uploader is in HTML5 mode. If filtering by extension is needed across all Uploader modes, it is best to implement it post-selection, by validating individual elements in the fileList.
log	No longer exists. All necessary uploader information is transmitted via events.
multiFiles	Renamed to multipleFiles
transparent	No longer exists. The Uploader in Flash mode is now always rendered as a transparent overlay over a "Select Files" button that can be customized or replaced with any control using the selectFilesButton attribute.

Method changes

Method in 3.4.1	Change in 3.5.0
cancel	No longer exists on the Uploader instance. Instead, a cancelUpload() method is present on the instance of Uploader's queue, stored in uploaderInstance.queue. (See the API Docs for more information).
clearFileList	No longer exists. Instead, you can directly manipulate the fileList attribute.
enable	No longer exists. Instead, set the enabled attribute to either true or false.
disable	No longer exists. Instead, set the enabled attribute to either true or false.
removeFile	No longer exists. Instead, you can directly manipulate the fileList attribute.
upload	The method signature has changed. The new upload() method takes file, url, and postVars as arguments, where file is a references to an instance of Y.File (can be obtained from the fileList attribute), url is the target URL to upload the file to, and postVars is a set of key-value pairs specifying the variables that should be POSTed along with the file upload. The old method argument has been removed since file upload requests are always POSTed. The old postFileVarName argument has been replaced with an instance-level fileFieldName attribute. (See the API Docs for more information).
uploadAll	The method signature has changed. The new uploadAll() method takes url, and postVars as arguments, where url is the target URL to upload the files to, and postVars is a set of key-value pairs specifying the variables that should be POSTed along with the file upload. If POST variables need to be specified per file, you can use the postVarsPerFile attribute instead of specifying the third argument. The old method argument has been removed since file upload requests are always POSTed. The old postFileVarName argument has been replaced with an instance-level fileFieldName attribute. (See the API Docs for more information).
uploadThese	The method signature has changed. The new uploadThese() method takes files, url, and postVars as arguments, where files is an array of Y.File instances (can be obtained as a subset of fileList attribute), url is the target URL to upload the files to, and postVars is a set of key-value pairs specifying the variables that should be POSTed along with the file upload. If POST variables need to be specified per file, you can use the postVarsPerFile attribute instead of specifying the third argument. The old method argument has been removed since file upload requests are always POSTed. The old postFileVarName argument has been replaced with an instance-level fileFieldName attribute. (See the API Docs for more information).

Improved Progressive Enhancement

The progressive enhancement scenario has been improved in 3.5.0 Uploader. The Uploader now keeps a static TYPE property (Y.Uploader.TYPE), which you can check before creating an instance of Uploader or modifying its configuration settings. We recommend the following pattern for using Uploader on your pages:

if (Y.Uploader.TYPE != "none") {
    
    var uploaderInstance = new Y.Uploader(....); // Common configuration settings.

    if (Y.Uploader.TYPE == "html5") {
      // Additional configuration settings for an HTML5 uploader,
      // e.g. a drag-and-drop area specification, etc.
    }

    else if (Y.Uploader.TYPE == "flash") {
      // Flash-specific configuration settings, 
      // e.g. a fileFilters setting, etc.
   }

   // Render the uploader
   uploaderInstance.render("#selectFilesButtonContainer");
}

else {
    
    // Don't render the uploader and use predefined basic functionality
    // instead (e.g. a simple upload form field).

}

Backend Setup

The backend requirements for the Flash version of the Uploader have not changed. However, the XMLHttpRequest Level 2 cross-domain request security model is different from that in Flash, and needs a different type of verification from the backend that receives POST requests with uploaded files. See the Backend Setup section in the User Guide for more information, or read more about it on the HTML5Rocks website.

What Did We Miss?

Obviously, there were quite a few changes to Uploader from 3.4.1 to 3.5.0. It's likely that we missed something here. If you experience trouble with your upgrade and find this migration guide is missing something important, please file a ticket and we'll update it as soon as possible.

Additional resources to help with the upgrade include the forums, and the #yui IRC channel on freenode.net.