Add abstract eloquent casts

docs/advanced-usage/eloquent-casting.md

@@ -40,6 +40,94 @@ This will internally be converted to a data object which you can later retrieve
 Song::findOrFail($id)->artist; // ArtistData object
 ```
 
+### Abstract data objects
+
+Sometimes you have an abstract parent data object with multiple child data objects, for example:
+
+```php
+abstract class RecordConfig extends Data
+{
+    public function __construct(
+        public int $tracks,
+    ) {}
+}
+
+class CdRecordConfig extends RecordConfig
+{
+    public function __construct(
+        int $tracks
+        public int $bytes,
+    ) {
+        parent::__construct($tracks);
+    }
+}
+
+class VinylRecordConfig extends RecordConfig
+{
+    public function __construct(
+        int $tracks
+        public int $rpm,
+    ) {
+        parent::__construct($tracks);
+    }
+}
+```
+
+A model can have a JSON field which is either one of these data objects:
+
+```php
+class Record extends Model
+{
+    protected $casts = [
+        'config' => RecordConfig::class,
+    ];
+}
+```
+
+You can then store either a `CdRecordConfig` or a `VinylRecord` in the `config` field:
+
+```php
+$cdRecord = Record::create([
+    'config' => new CdRecordConfig(tracks: 12, bytes: 1000),
+]);
+
+$vinylRecord = Record::create([
+    'config' => new VinylRecordConfig(tracks: 12, rpm: 33),
+]);
+
+$cdRecord->config; // CdRecordConfig object
+$vinylRecord->config; // VinylRecordConfig object
+```
+
+When a data object class is abstract and used as an Eloquent cast then this feature will work out of the box.
+
+The child data object value of the model will be stored in the database as a JSON string with the class name as the key:
+
+```json
+{
+    "type": "\\App\\Data\\CdRecordConfig",
+    "value": {
+        "tracks": 12,
+        "bytes": 1000
+    }
+}
+```
+
+When retrieving the model, the data object will be instantiated based on the `type` key in the JSON string.
+
+#### Abstract data class morphs
+
+By default, the `type` key in the JSON string will be the fully qualified class name of the child data object. This can break your application quite easily when you refactor your code. To prevent this, you can add a morph map like with [Eloquent models](https://laravel.com/docs/10.x/eloquent-relationships#polymorphic-relationships). Within your `AppServiceProvivder` you can add the following mapping:
+
+```php
+use Spatie\LaravelData\Support\DataConfig;
+
+app(DataConfig::class)->enforceMorphMap([
+    'cd_record_config' => CdRecordConfig::class,
+    'vinyl_record_config' => VinylRecordConfig::class,
+]);
+```
+
 ## Casting data collections
 
 It is also possible to store data collections in an Eloquent model:

src/Concerns/BaseData.php

@@ -106,6 +106,14 @@ public function transform(
         return DataTransformer::create($transformValues, $wrapExecutionType, $mapPropertyNames)->transform($this);
     }
 
+    public function getMorphClass(): string
+    {
+        /** @var class-string<\Spatie\LaravelData\Contracts\BaseData> $class */
+        $class = static::class;
+
+        return app(DataConfig::class)->morphMap->getDataClassAlias($class) ?? $class;
+    }
+
     public function __sleep(): array
     {
         return app(DataConfig::class)->getDataClass(static::class)

src/Contracts/BaseData.php

@@ -35,4 +35,6 @@ public static function normalizers(): array;
     public static function pipeline(): DataPipeline;
 
     public static function empty(array $extra = []): array;
+
+    public function getMorphClass(): string;
 }

src/Support/DataClass.php

@@ -35,6 +35,7 @@ public function __construct(
         public readonly Collection $methods,
         public readonly ?DataMethod $constructorMethod,
         public readonly bool $isReadonly,
+        public readonly bool $isAbstract,
         public readonly bool $appendable,
         public readonly bool $includeable,
         public readonly bool $responsable,
@@ -68,6 +69,7 @@ public static function create(ReflectionClass $class): self
             methods: self::resolveMethods($class),
             constructorMethod: DataMethod::createConstructor($constructor, $properties),
             isReadonly: method_exists($class, 'isReadOnly') && $class->isReadOnly(),
+            isAbstract: $class->isAbstract(),
             appendable: $class->implementsInterface(AppendableData::class),
             includeable: $class->implementsInterface(IncludeableData::class),
             responsable: $class->implementsInterface(ResponsableData::class),

src/Support/DataClassMorphMap.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace Spatie\LaravelData\Support;
+
+use Spatie\LaravelData\Contracts\BaseData;
+
+class DataClassMorphMap
+{
+    /** @var array<string, class-string<BaseData>> */
+    protected array $map = [];
+
+    /** @var array< class-string<BaseData>, string> */
+    protected array $reversedMap = [];
+
+
+    /**
+     * @param string $alias
+     * @param class-string<BaseData> $class
+     */
+    public function add(
+        string $alias,
+        string $class
+    ): self {
+        $this->map[$alias] = $class;
+        $this->reversedMap[$class] = $alias;
+
+        return $this;
+    }
+
+    /**
+     * @param array<string, class-string<BaseData>> $map
+     */
+    public function merge(array $map): self
+    {
+        foreach ($map as $alias => $class) {
+            $this->add($alias, $class);
+        }
+
+        return $this;
+    }
+
+    public function getMorphedDataClass(string $alias): ?string
+    {
+        return $this->map[$alias] ?? null;
+    }
+
+
+    /**
+     * @param class-string<BaseData> $class
+     */
+    public function getDataClassAlias(string $class): ?string
+    {
+        return $this->reversedMap[$class] ?? null;
+    }
+}

src/Support/DataConfig.php

@@ -4,6 +4,7 @@
 
 use ReflectionClass;
 use Spatie\LaravelData\Casts\Cast;
+use Spatie\LaravelData\Contracts\BaseData;
 use Spatie\LaravelData\Transformers\Transformer;
 
 class DataConfig
@@ -23,6 +24,8 @@ class DataConfig
     /** @var \Spatie\LaravelData\RuleInferrers\RuleInferrer[] */
     protected array $ruleInferrers;
 
+    public readonly DataClassMorphMap $morphMap;
+
     public function __construct(array $config)
     {
         $this->ruleInferrers = array_map(
@@ -37,6 +40,8 @@ public function __construct(array $config)
         foreach ($config['casts'] ?? [] as $castable => $cast) {
             $this->casts[ltrim($castable, ' \\')] = app($cast);
         }
+
+        $this->morphMap = new DataClassMorphMap();
     }
 
     public function getDataClass(string $class): DataClass
@@ -50,7 +55,7 @@ public function getDataClass(string $class): DataClass
 
     public function getResolvedDataPipeline(string $class): ResolvedDataPipeline
     {
-        if (array_key_exists($class,  $this->resolvedDataPipelines)) {
+        if (array_key_exists($class, $this->resolvedDataPipelines)) {
             return $this->resolvedDataPipelines[$class];
         }
 
@@ -94,6 +99,14 @@ public function getRuleInferrers(): array
         return $this->ruleInferrers;
     }
 
+    /**
+     * @param array<string, class-string<BaseData>> $map
+     */
+    public function enforceMorphMap(array $map): void
+    {
+        $this->morphMap->merge($map);
+    }
+
     public function reset(): self
     {
         $this->dataClasses = [];

src/Support/EloquentCasts/DataEloquentCast.php

@@ -6,15 +6,19 @@
 use Spatie\LaravelData\Contracts\BaseData;
 use Spatie\LaravelData\Contracts\TransformableData;
 use Spatie\LaravelData\Exceptions\CannotCastData;
+use Spatie\LaravelData\Support\DataConfig;
 
 class DataEloquentCast implements CastsAttributes
 {
+    protected DataConfig $dataConfig;
+
     public function __construct(
         /** @var class-string<\Spatie\LaravelData\Contracts\BaseData> $dataClass */
         protected string $dataClass,
         /** @var string[] $arguments */
         protected array $arguments = []
     ) {
+        $this->dataConfig = app(DataConfig::class);
     }
 
     public function get($model, string $key, $value, array $attributes): ?BaseData
@@ -29,6 +33,13 @@ public function get($model, string $key, $value, array $attributes): ?BaseData
 
         $payload = json_decode($value, true, flags: JSON_THROW_ON_ERROR);
 
+        if ($this->isAbstractClassCast()) {
+            /** @var class-string<BaseData> $dataClass */
+            $dataClass = $this->dataConfig->morphMap->getMorphedDataClass($payload['type']) ?? $payload['type'];
+
+            return $dataClass::from($payload['data']);
+        }
+
         return ($this->dataClass)::from($payload);
     }
 
@@ -38,7 +49,9 @@ public function set($model, string $key, $value, array $attributes): ?string
             return null;
         }
 
-        if (is_array($value)) {
+        $isAbstractClassCast = $this->isAbstractClassCast();
+
+        if (is_array($value) && ! $isAbstractClassCast) {
             $value = ($this->dataClass)::from($value);
         }
 
@@ -50,6 +63,18 @@ public function set($model, string $key, $value, array $attributes): ?string
             throw CannotCastData::shouldBeTransformableData($model::class, $key);
         }
 
+        if ($isAbstractClassCast) {
+            return json_encode([
+                'type' => $this->dataConfig->morphMap->getDataClassAlias($value::class) ?? $value::class,
+                'data' => $value->toJson(),
+            ]);
+        }
+
         return $value->toJson();
     }
+
+    protected function isAbstractClassCast(): bool
+    {
+        return $this->dataConfig->getDataClass($this->dataClass)->isAbstract;
+    }
 }

tests/Fakes/AbstractData/AbstractData.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace Spatie\LaravelData\Tests\Fakes\AbstractData;
+
+use Spatie\LaravelData\Data;
+
+abstract class AbstractData extends Data
+{
+}

tests/Fakes/AbstractData/AbstractDataA.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Spatie\LaravelData\Tests\Fakes\AbstractData;
+
+class AbstractDataA extends AbstractData
+{
+    public function __construct(
+        public string $a,
+    ) {
+    }
+}

tests/Fakes/AbstractData/AbstractDataB.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Spatie\LaravelData\Tests\Fakes\AbstractData;
+
+class AbstractDataB extends AbstractData
+{
+    public function __construct(
+        public string $b,
+    ) {
+    }
+}

tests/Fakes/Models/DummyModelWithCasts.php

@@ -6,13 +6,15 @@
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Support\Facades\Schema;
 use Spatie\LaravelData\DataCollection;
+use Spatie\LaravelData\Tests\Fakes\AbstractData\AbstractData;
 use Spatie\LaravelData\Tests\Fakes\SimpleData;
 
 class DummyModelWithCasts extends Model
 {
     protected $casts = [
         'data' => SimpleData::class,
         'data_collection' => DataCollection::class.':'.SimpleData::class,
+        'abstract_data' => AbstractData::class,
     ];
 
     public $timestamps = false;
@@ -24,6 +26,7 @@ public static function migrate()
 
             $blueprint->text('data')->nullable();
             $blueprint->text('data_collection')->nullable();
+            $blueprint->text('abstract_data')->nullable();
         });
     }
 }