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Custom fields

Custom fields allow you to create field types to be used for custom fields. Instances of these field types can be added to the respective areas that implement Custom fields API. Currently in Moodle core only courses implement this API, however custom fields are also used in addon plugins for other areas. For example, if you want to display radio buttons on the course edit page, then you can add an instance of a radio custom field plugin to the Course custom fields configuration.

File structure​

Custom field plugins are located in the /customfield/field directory. A plugin should not include any custom files outside of it's own plugin folder.

Each plugin is in a separate subdirectory and consists of a number of mandatory files and any other files the developer is going to use.

info

Some of the important files are described below. See the common plugin files documentation for details of other files which may be useful in your plugin.

View an example directory layout for the `customfield_checkbox` plugin.
customfield/field/checkbox
├── classes
│   ├── data_controller.php
│   ├── field_controller.php
│   └── privacy
│       └── provider.php
├── lang
│   └── en
│       └── customfield_checkbox.php
└── version.php

A custom field plugin requires two controller classes:

  • a field controller, which describes the field itself; and
  • a data controller, which describes with interface within the context of the instance (i.e. course).

Field Controller​

The field controller defines the available configuration options that an administrator can select within the user interface to configure the field.

Examples might include the prompt to show alongside the custom field element, and whether the element is required.

Class naming

The class must be named field_controller within your plugin's namespace (for example customfield_myfield) and must extend the \core_customfield\field_controller class.

The \core_customfield\field_controller class is an abstract class and defines a number of functions which you can choose to override. At a minimum, the following two items are required:

  • the TYPE constant to match the name of the plugin; and
  • the config_form_definition() function.
Element names

All element names must be in the format $configdata[configname] for values to be saved, for example configdata[cfgdefault].

In addition to these requried a functions a number of other functions exist and can be overridden, with the following being particularly useful:

  • config_form_validation($formdata, $formfiles) - control the form validation

Details of all available functions can be found in the \core_customfield\field_controller class defined in /customfield/classes/field_controller.php.

Data Controller​

The data controller defines the user interface that teachers use within the course edit form.

Class naming

The class must be named data_controller within your plugin's namespace (for example customfield_myfield) and must extend the \core_customfield\data_controller class.

The \core_customfield\data_controller class is an abstract class and defines a number of functions which you can choose to override. At a minimum, the following two items are required:

  • the datafield(): string function; and
  • the instance_form_definition() function.

datafield()​

The datafield() function returns an enumerated string and describes which database field the data for the custom field is stored in. The possible options are:

  • intvalue - can store integer values, this field is indexed
  • decvalue - can store decimal values
  • shortcharvalue - can store character values up to 255 characters long, this field is indexed
  • charvalue - can store character values up to 1333 characters long, this field is not indexed
  • value - can store character values of unlimited length ("text" field in the db)

instance_form_definition()​

The instance_form_definition() function adds any required field elements that are displayed on the instance editing page (i.e. on the course settings page).

See Also​