Extending

The panel can be extended on two levels:

• PHP classes you already extend in your application (entities, actions, filters, metrics, events). They need no JavaScript, and the pages below describe each of them.
• The public extension API (since 1.5): your own Vue components for fields, cards, filters and sidebar pages, your own routes and translations, and overriding the UI of built-in components. An extension is a Composer package (or a directory in the application) and plugs in without rebuilding the panel. Guide: Extensions: the public API.

What you can extend#

A field with a built-in component#

A custom field class that only changes server behaviour (rules, filling, formatting) can use the component of a built-in field. For example, a subclass of Text uses text-field:

use Maxcxam\Larsadmin\Fields\Text;

class Slug extends Text
{
    protected function formatForDisplay(mixed $value): mixed
    {
        return $value === null ? null : '/'.$value;
    }
}

Since 1.5 the protected hooks of Field (resolveValue(), formatForDisplay(), fillValue(), fillString(), typeRules(), implicitRules(), acceptsNullInput(), defaultAlign()), the public hooks and jsonSerialize() are stable API for subclasses (the full list is in Custom fields). A field with its own Vue component is described there too.

Custom array fields and forms with files#

A form that contains a File or Image field, or a field with multipart: true (see Fields that upload files), is sent as multipart/form-data (see Files and images). Such a request does not carry empty arrays at all: if the user cleared a custom field whose value is an array, the field's key is missing, and fill() keeps the old value. In a JSON form without such fields the same field receives []. Built-in fields are not affected. If your field takes an array, either send a presence flag with it (like the present key of file fields) or treat a missing key as an empty array.

The component registry#

The server-side component key of a field, filter or card is matched to a Vue component through the panel's registry. Since 1.5 the registry is open to extensions through defineExtension() of the larsadmin module, and the built-in components register in it the same way. The internal functions registerField, registerFilter and registerCard remain as wrappers and are not API.

How the panel handles a key:

Keys of the built-in components:

How to build and test the package itself: the "Developing the package" section of Installation.

Next: List interface.