# The Basics

# Introduction

Schemas describe JSON:API resources that exist within your server. For Eloquent models, they also describe how the JSON:API server interacts with the database to query, create, read, update and delete resources.

Schemas are also used to automatically serialize models to JSON:API resource objects, unless you define your own serialization using our resource classes.

# Defining Schemas

By default, schemas exist in a namespace relative to the namespace of your Server class. The pluralized form of the JSON:API resource type is used as the namespace.

For example, if the App\JsonApi\V1\Server has a resource called posts, the schema will exist as App\JsonApi\V1\Posts\PostSchema.

You may generate a new schema using the jsonapi:schema Artisan command:

php artisan jsonapi:schema posts --server=v1

TIP

The --server option is not required if you only have one server.

The most basic and fundamental property of a schema is its model property. This property tells the server which Eloquent model the schema corresponds to:

/**
 * The model the schema corresponds to.
 *
 * @var string
 */
public static string $model = \App\Models\Post::class;

When generating your schema, we set the $model property for you. The model class is assumed to be the name of the schema - i.e. the Post model for the PostSchema class. If you need to use a different model class, use the --model option with the generator:

php artisan jsonapi:schema posts --server=v1 --model=BlogPost

Freshly created schemas only contain id, createdAt and updatedAt fields. Don't worry, we'll add more fields to our schema soon.

# Parent Classes and Interfaces

Our schemas support setting the $model property of a schema to a parent class or an interface.

When matching models to schemas, a direct match will always be resolved first. If there is no direct match, we then check whether the model class has a parent for which a schema is registered. If no parent, we then check whether the model class implements any interfaces for which a schema is registered.

# Registering Schemas

Before resources are available in your server, they must first be registered with the server. Resources are registered in the allSchemas() method of your server class.

For example, to register our PostSchema:

namespace App\JsonApi\V1;

use LaravelJsonApi\Core\Server\Server as BaseServer;

class Server extends BaseServer
{

    // ...

    /**
     * Get the server's list of schemas.
     *
     * @return array
     */
    protected function allSchemas(): array
    {
        return [
            Posts\PostSchema::class,
        ];
    }
}

TIP

We do not support automatic discovery of schemas intentionally. Although our directory conventions mean it would be possible to detect schemas, it is inefficient to run discovery code on every HTTP request. Manually registering schemas makes your API more efficient.

Once your schema class is registered, your server is able to auto-discover any additional classes for the resource - for example, Request or Resource classes.

# Resource Type

By default, the JSON:API resource type is the plural and dasherized version of the class name that appears before Schema.

For example, the resource type for PostSchema will be posts. For BlogPostSchema it will be blog-posts.

You can easily override this default behaviour if needed. For example, if we wanted the resource type for our PostSchema to be blog_posts, we would implement the static type() method on our schema:

class PostSchema extends Schema
{

    /**
     * Get the JSON:API resource type.
     *
     * @return string
     */
    public static function type(): string
    {
        return 'blog_posts';
    }
}

# URI Type

When the resource type appears in resource URIs, we use the dash-case form of the resource type. Therefore blogPosts or blog_posts will be /blog-posts. This follows our default convention of dash-casing URLs.

This can be customised by setting the $uriType property on your schema. For example, if we wanted to underscore the type in the URI:

class BlogPostSchema extends Schema
{
   /**
    * The resource type as it appears in URIs.
    *
    * @var string|null
    */
    protected ?string $uriType = 'blog_posts';
}

If you need to programmatically work out the URI type, then overload the uriType() method. If you're doing this, we recommend caching the value as it is likely to be used a lot of times. For example:

class BlogPostSchema extends Schema
{
   /**
    * The resource type as it appears in URIs.
    *
    * @return string
    */
    public function uriType(): string
    {
        if ($this->uriType) {
            return $this->uriType;
        }

        return $this->uriType = '...calculated value';
    }
}

When models are serialized to JSON:API resources, a self link for the resource is included in the JSON representation by default.

According the the JSON:API specification, if a resource has a self link, a GET request to the link MUST return the resource. If you have a resource that is not retrievable by its resource identifier, then you must disable the self link. To do this, set the $selfLink property on your schema to false:

class PostSchema extends Schema
{
    /**
     * Whether resources of this type have a self link.
     *
     * @var bool
     */
    protected bool $selfLink = false;

    // ...
}

WARNING

If you disable the self link on a schema, the resource's relationships will no longer have self and related links in the relationship object. This is because it does not make sense to have relationship endpoints when the resource itself is not retrievable via a self link.

# Fields

In the JSON:API specification, a resource object's attributes and relationships are collectively called its fields.

Fields share a common namespace with each other and with the resource object's type and id. This means a resource cannot have an attribute and a relationship with the same name, nor can there be an attribute or relationship named type or id.

Each schema contains a fields method. This method returns an array of fields, which define the ID, attributes and relationships of the resource that the schema describes. To add a field to a schema, we simply add it to the schema's fields method. Typically fields may be created using their static make method.

Fields are described in more detail in subsequent chapters, but here is an example for a posts resource:

namespace App\JsonApi\V1\Posts;

use LaravelJsonApi\Eloquent\Fields\DateTime;
use LaravelJsonApi\Eloquent\Fields\ID;
use LaravelJsonApi\Eloquent\Fields\Relations\BelongsTo;
use LaravelJsonApi\Eloquent\Fields\Relations\BelongsToMany;
use LaravelJsonApi\Eloquent\Fields\Relations\HasMany;
use LaravelJsonApi\Eloquent\Fields\Str;
use LaravelJsonApi\Eloquent\Schema;

class PostSchema extends Schema
{

    // ...

    /**
     * @inheritDoc
     */
    public function fields(): array
    {
        return [
            ID::make(),
            BelongsTo::make('author')->type('users')->readOnly(),
            HasMany::make('comments')->readOnly(),
            Str::make('content'),
            DateTime::make('createdAt')->sortable()->readOnly(),
            Str::make('slug'),
            Str::make('synopsis'),
            BelongsToMany::make('tags'),
            Str::make('title')->sortable(),
            DateTime::make('updatedAt')->sortable()->readOnly(),
        ];
    }

}

# Multi-Resource Models

Typically each model class is represented in your API as a single resource type. E.g. our Post model is represented as a posts resource.

There may however be occasions where you need to represent an Eloquent model as multiple resource types in your API. To do this, follow the instructions in the Multi-Resource Models chapter.

Last Updated: 4/20/2021, 1:51:15 PM