A Reusable Zend Framework Content Module

As a sort of proof of concept for the ideas I discussed in my previous post, I've put together the first draft of what could become a very helpful reusable module. With this post, I'd like to introduce my new Zend Framework "content" module, which provides several abstract components for a reusable model layer, along with a concrete framework for building a variety of content types sharing a common database-based persistence layer. With some (OK, a lot of) refinements, a module like this could easily form the foundation of an extremely extensible Zend Framework-based content management system.

You can check out the current trunk by issuing the following svn command in your project's modules directory:

git clone git://github.com/jazzslider/zf-content.git

Here’s a more detailed look at the features:

  • First off, it provides a reusable abstract model-and-mapper[1] system with sensible defaults for persisting those models in a MySQL database (other kinds of persistence layers are easily supported). Both pieces incorporate a plugin architecture similar to that used in Zend_Controller_Action, so that new functionality can be added to all models compositionally.
  • It also provides a concrete implementation of all this called Content_Model_Post; this model is essentially just your basic revision-controlled title-and-body content type. The nice thing about the post model is that it's designed to be extended; if you need additional fields, you simply need to write a child class and a mapper plugin that describes how to find the extra data. (The design concept owes a lot to the Drupal CCK module, but without any of the administrative bells and whistles; this module is still very much a programmer's toolkit.)
  • The view layer for the posts system comes with a few handy helpers and filters; the filters are mainly for implementing things like HTMLPurifier, Markdown, GeSHi syntax highlighting, etc. in the view layer when rendering your content. The idea is described in more detail in one of my previous posts, but the solution I've implemented here is much better. One caveat: the filters won't work unless you've got the associated libraries installed somewhere in your include_path (as described in the INSTALL.txt file in the root of the project).

I’m releasing the current version of the source code under the GPL for now so that anyone who wants to can see how it works; that said, I wouldn’t say it’s ready for use in a high-profile production environment, owing to a couple of factors:

  • While the system does keep track of content authorship right out of the box, it would do a much better job of it if it knew how its parent application kept track of the current user. The only expectation it enforces is that when you assign an author to a post, it either has to be a Zend_Acl_Role_Interface object implementation or a string role ID that can be resolved to such an object at runtime (you can control this part of the process through a model plugin). Once I’ve written my reusable “users” module, things may work more predictably.
  • While we’re on the subject of related modules…one of my next projects is to develop a “comments” module that provides comments to all posts (and all dependent content types). For that matter, I’d also like to piece together something that allows for tag-based content classification. These will all be separate, optional modules, in keeping with the idea that people should be able to drop in what they want and leave the rest aside.
  • The process of designing a new dependent content type is still a little over-complicated; I’m going to try writing a tutorial soon, and when I do, I’d love some feedback on how to simplify the process.
  • The code is not yet unit tested; I wasn’t quite sure of the best way to bootstrap my unit tests now that Zend_Application is involved, and so far I haven’t found any definitive guides on the matter. I’ll be looking into that soon, and if what I discover is useful I’ll certainly make a post about it.

At any rate, please take a look and tell me what you think; remember, this mainly serves as a proof of concept for some of the stuff I’ve been talking about in previous posts…and once I’ve got the other helper modules put together, I think it’ll be a lot clearer what I’m aiming at. Anyway, thanks for reading!

Footnotes

  • [Back] The data mapper logic in this module accomplishes some of the same purposes as the proposed Zend_Db_Mapper component, but is in no way intended (or suitable) to replace it. My goal here was mainly to demonstrate how such logic could be built out as a distributable, reusable plug-and-play module now that Zend_Application_Resource_Modules is out of the gate. I'm looking forward to future developments on Zend_Db_Mapper, and if it finds its way into the official framework you can bet I'll be using it for projects like this.
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