Creating a custom field formatter

Field formatters define the way in which a field type will be presented. These formatters return the render array information to be processed by the theming layer. Field formatters are configured on the display mode interfaces.

In this recipe, we will create a formatter for the field created in the Creating a custom field type recipe in this chapter. The field formatter will display the first and last names with some settings.

Getting ready

Create a new module like the one existing in the first recipe. We will refer to the module as mymodule throughout the recipe. Use your module's appropriate name.

How to do it...

1. We will need to create the src/Plugin/Field/FieldFormatter directory in the module's base location. The Field module discovers field formatters in the Plugin\Field\FieldFormatter namespace.
2. Create a RealNameFormatter.php file in the newly created directory so that we can define the RealNameFormatter class. This will provide a custom form element to...