About Field Types
Field Types are the most granular building blocks for content managed by eZ Platform. The system comes with about 30 native types that cover most common needs (Text line, Rich text, Email, Author list, Content relation, Map location, Float, etc.)
Field Types are responsible for:
storing data, either using the native storage engine mechanisms, or specific means
validating input data
making the data searchable (if applicable)
displaying an instance of the type
Custom Field Types are a very powerful type of extension, since they allow you to hook deep into the content model.
You can find the in-depth documentation about Field Types and their best practices. It describes how each component of a Field Type interacts with the various layers of the system, and how to implement those.
About this tutorial
This tutorial aims at covering the conception and development of a custom eZ Platform Field Type.
We will do this by implementing a Tweet Field Type. It will:
accept as input the URL of a tweet (https://twitter.com/<username>/status/<id>)
fetch the tweet using the twitter oEmbed API (https://dev.twitter.com/docs/embedded-tweets)
store the tweet’s embed contents and URL
display the tweet's embedded version when displaying the field from a template
Getting the code
The code created throughout this tutorial is available on github: https://github.com/ezsystems/TweetFieldTypeBundle.
Field Types, like any other eZ Platform plugin, must be provided as Symfony 2 bundles. This chapter will cover the creation and organization of this bundle
Read more about Creating the bundle and structuring the bundle.
This part will cover the implementation of the eZ Platform API elements required to implement a custom Field Type
Read more about Implementing the Tweet\Value class and Implementing the Tweet\Type class.
Storing data from any Field Type into the Legacy Storage Engine requires that your custom data is mapped to the data model.
Read more about Implementing the Legacy Storage Engine Converter.
Displaying a Field Type's data is done through a Twig template.
Read more about implementing the Field Type template.
You should ideally read the general extensibility documentation for PlatformUI. The part about templating covers view templates. Edit templates are not documented at the time of writing, but Netgen has published a tutorial that covers the topic: http://www.netgenlabs.com/Blog/Adding-support-for-a-new-field-type-to-eZ-Publish-Platform-UI.