archetypes.uploadreferencewidget 0.2

The problem

One of the biggest issues we have seen re-using file assets in the Plone CMS is that once a file is uploaded as an attribute of content; you can not easily reuse it. Take this scenerio for instance:

• You create a ‘News Item’ in ‘/news/foo.html’ and upload an image, ‘logo.jpg’, that shows a picture of a corporate logo. To address this image you must goto a URL like, ‘http://host/news/foo.html/logo.jpg’.

• Two weeks later you create another ‘News Item’ in ‘/news/bar.html’ and you dont want to re-upload the corporate logo. You simply want to reuse the existing corporate logo. Where do you find it?

• We could browse content and goto ‘/news/foo.html’ and inside the ‘News Item’ see the ‘logo.jpg’. While this is possible. It is not probable that someone has created a container where images are being uploaded. Specifically the default Plone ‘News Item’ implementation does not work this way.

The suggested solution

Create a new ‘UploadReferenceWidget’. What this will do is be an alternative widget that can work in-place of a ReferenceWidget; and should retain all the functionality of a Reference Field/Widget. But enable someone to upload a ‘File’. The policy on the Field/Widget could dictate that the file gets put into a certain folder. Take this scenerio for instance:

• We know that all content in ‘http://host/corporate/news’ is commercial news.

• When user is creating a ‘News Item’ and uploads ‘logo2.jpg’ into the Upload Reference Widget called ‘image’ that we will ask the policy Where does this image, ‘logo2.jpg’ go? The policy could put it in /images/logos.

• The policy would have to do everything. The Widget wouldn’t help anything. The file would be put into the ‘/images/logos’ folder and then in the ‘News Item’ image attribute would be the reference id to the ‘/images/logos/logo2.jpg’.

Implementation details

The new widget has two main features:

• Upload a new file: create a new object and make a reference to it

• Select an existing object: make a reference to it

When uploading a new file, the widget checks for the mimetype and create an instance of the appropriate content-type: File or Image. This content is created in the ‘startup_directory’ property defined in the widget.

Example usage

Take a look in the ‘demo.py’ file for a simple example usage of this widget.

The browse and select functionality is provided by ‘archetypes.referencebrowserwidget’, which means you can use any of its current features.

Check the “complete reference of available options”:http://tinyurl.com/referencebrowserwidget-options online.

It contains the list of default property values and explains its meanings.

0.2 - 2009-03-22

• Added our skin layer to all skins paths. [deo]

• Fixed dependency registration on both metadata.xml and configure.zcml. [deo]

0.1-alpha - Unreleased

• Initial release