"General Type": a new criterion for Plone Collections

A new 1.2 version of plone.app.querystring has been released.
There are some improvement and bugfix but I'm particularly interested in one new feature: customizable parsed query. Why?

Some times ago I started developing a new product for providing some usability enhancement in type categorization using Collection but it was a dead end: it wont work without patching Plone. But the accepted pull request changed everything, so here it is: collective.typecriterion.

The product want to replace the Collection's "Types" search term (adding a new search term called "General type").

The scope of the add-on is to fix some usability issues with Collections:

• Users don't always understand all of the content types installed in the site
• User don't always get the difference from a type to another (classical examples: Page and File, or File and Image)

Also there are some missing features:

• There's not way to quickly define a new type alias or exclude types from the list
• There's no way to group types under a general (but more user friendly) new type

Some of the point above could be reached searching types using interfaces (through object_provides index) instead of portal_type (the attribute that commonly store primitive type name of every content, but:

• although search by interface is the suggested way to search by types, it's not used anywhere by Plone UI
• using interfaces lead to inheritance behavior (which is great... until you really want it)
• sometimes you don't have the right interface to use. For example, there's an ITextContent interface in ATContentTypes, but it's implemented only by Page and News, not by Event. And generating new interfaces is a developer task

The idea is to keep using portal_type but give administrators a way to group and organize them in a more friendly form.

After installation the new control panel entry "Type criterion settings" will be available.
The target of the configuration panel is simple: is possible to group a set of types under the cloak of a new descriptive type name. In the example given in the image we take again definition of a "textual" content (a content that contains rich text data), grouping all the know types.

After the configuration you can start using the new search term.
Usability apart there's also another advantage in this approach, that is the integration with 3rd party products.

Let say that you defined a new general type called "Multimedia" and you configure it as a set that contains Image and Video, and let say that Video went from the installation of redturtle.video product.
After a while you plan a switch from redturtle.video to wildcard.media. What you need to do is simply to change the configuration of the general type, not all the collections in the site.

Finally an interesting note: the code inside the collective.typecriterion is really small. All the magic (one time again) came from Plone.