prefill_plugins.rst

Prefill plugins

Open Forms has a plugin system for the prefill module. The prefill module is invoked when form step (or rather, submission steps) are retrieved from the API to obtain the FormioJS configuration. In the form builder, it's possible to specify which plugin and plugin-specific attribute to use to prefill the default value.

Each plugin is responsible for fetching the relevant data from the plugin-specific backend, which could be StUF-BG, HaalCentraal BRP or Chamber of Commerce for example.

Developing plugins

Every possible backend can be implemented as a plugin, and registered with Open Forms.

Registering the plugin makes it available for content-editors to select as possible prefill option for a form field.

You can find an example implementation in openforms.prefill.contrib.demo.

Implementation

Plugins must implement the interface from openforms.prefill.base.BasePlugin. It's safe to use this as a base class.

There are two relevant public methods:

get_available_attributes

provide an iterable of (identifier, label) tuples. This is used to pre-populate/ display the list of attributes that can be selected by content-editors.

get_prefill_values

the actual implementation of the prefill functionality. This is invoked inside the request-response cycle of certain API endpoints.

Public Python API

Plugin base class

openforms.prefill.base.BasePlugin

Module documentation

openforms.prefill