> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/spatie/laravel-data/llms.txt
> Use this file to discover all available pages before exploring further.

# Internal Structures

> Reference for internal data structures used when writing casts, transformers, and rule inferrers

Laravel Data uses internal structures to analyze data objects and their properties. These structures are helpful when writing casts, transformers, or rule inferrers.

## DataClass

Represents the structure of a data object.

### Properties

* `name` - Name of the data class
* `properties` - All `DataProperty` objects of the class
* `methods` - All magical creation `DataMethod` objects
* `constructorMethod` - The constructor `DataMethod`
* `isReadOnly` - Whether the class is read-only
* `isAbstract` - Whether the class is abstract
* `appendable` - Whether the class implements `AppendableData`
* `includeable` - Whether the class implements `IncludeableData`
* `responsable` - Whether the class implements `ResponsableData`
* `transformable` - Whether the class implements `TransformableData`
* `validatable` - Whether the class implements `ValidatableData`
* `wrappable` - Whether the class implements `WrappableData`
* `emptyData` - Whether the class implements `EmptyData`
* `attributes` - Collection of resolved attributes assigned to the class
* `dataCollectablePropertyAnnotations` - Property annotations used to infer data collection type
* `allowedRequestIncludes` - Allowed request includes
* `allowedRequestExcludes` - Allowed request excludes
* `allowedRequestOnly` - Allowed request only
* `allowedRequestExcept` - Allowed request except
* `outputMappedProperties` - Property names mapped when transforming
* `transformationFields` - Structure of transformation fields

## DataProperty

Represents a single property within a data object.

### Properties

* `name` - Name of the property
* `className` - Name of the class of the property
* `type` - The `DataPropertyType` of the property
* `validate` - Whether the property should be automatically validated
* `computed` - Whether the property is computed
* `hidden` - Whether the property is hidden when transforming
* `isPromoted` - Whether the property is constructor promoted
* `isReadOnly` - Whether the property is read-only
* `hasDefaultValue` - Whether the property has a default value
* `defaultValue` - The default value of the property
* `cast` - The cast assigned to the property
* `transformer` - The transformer assigned to the property
* `inputMappedName` - The name used to map an input property name
* `outputMappedName` - The name used to map an output property name
* `attributes` - Collection of resolved attributes assigned to the property

## DataMethod

Represents a method within a data object.

### Properties

* `name` - Name of the method
* `parameters` - All `DataParameter` and `DataProperty` objects of the method
* `isStatic` - Whether the method is static
* `isPublic` - Whether the method is public
* `isCustomCreationMethod` - Whether the method is a custom creation method (magical)
* `returnType` - The `DataType` of the return value

## DataParameter

Represents a single parameter/property within a data method.

### Properties

* `name` - Name of the parameter
* `isPromoted` - Whether the property/parameter is constructor promoted
* `hasDefaultValue` - Whether the parameter has a default value
* `defaultValue` - The default value of the parameter
* `type` - The `DataType` of the parameter

## DataType

Represents a type within a data object.

### Properties

* `Type` - Can be a `NamedType`, `UnionType`, or `IntersectionType`
* `isNullable` - Whether the type can be nullable
* `isMixed` - Whether the type is a mixed type
* `kind` - The `DataTypeKind` of the type

## DataPropertyType

Extends `DataType` with additional properties for data properties.

### Properties

Inherits all properties from `DataType`, plus:

* `isOptional` - Whether the type can be optional
* `lazyType` - The class of the lazy type for the property
* `dataClass` - The data object class or collection data class
* `dataCollectableClass` - The collectable type of data objects
* `kind` - The `DataTypeKind` of the type

## DataTypeKind

An enum representing the kind of type with respect to the package:

* `Default` - A non-package-specific type
* `DataObject` - A data object
* `DataCollection` - A `DataCollection` of data objects
* `DataPaginatedCollection` - A `DataPaginatedCollection` of data objects
* `DataCursorPaginatedCollection` - A `DataCursorPaginatedCollection` of data objects
* `DataArray` - An array of data objects
* `DataEnumerable` - An `Enumerable` of data objects
* `DataPaginator` - A `Paginator` of data objects
* `DataCursorPaginator` - A `CursorPaginator` of data objects

## NamedType

Represents a named PHP type.

### Properties

* `name` - The name of the type
* `builtIn` - Whether the type is a built-in type
* `acceptedTypes` - Array of accepted types as strings
* `kind` - The `DataTypeKind` of the type
* `dataClass` - The data object class or collection data class
* `dataCollectableClass` - The collectable type of data objects
* `isCastable` - Whether the type is a `Castable`

## UnionType / IntersectionType

Represents a union or intersection of types.

### Properties

* `types` - Array of types (can be `NamedType`, `UnionType`, or `IntersectionType`)

## Usage in Casts

```php theme={null}
use Spatie\LaravelData\Casts\Cast;
use Spatie\LaravelData\Support\DataProperty;
use Spatie\LaravelData\Support\Creation\CreationContext;

class CustomCast implements Cast
{
    public function cast(
        DataProperty $property, 
        mixed $value, 
        array $properties, 
        CreationContext $context
    ): mixed {
        // Access property information
        $propertyName = $property->name;
        $propertyType = $property->type;
        $isNullable = $property->type->isNullable;
        
        // Access the data class being created
        $dataClassName = $context->dataClass;
        
        // Perform casting logic
        return $value;
    }
}
```

## Usage in Transformers

```php theme={null}
use Spatie\LaravelData\Transformers\Transformer;
use Spatie\LaravelData\Support\DataProperty;
use Spatie\LaravelData\Support\Transformation\TransformationContext;

class CustomTransformer implements Transformer
{
    public function transform(
        DataProperty $property, 
        mixed $value, 
        TransformationContext $context
    ): mixed {
        // Access property information
        $propertyName = $property->name;
        $outputName = $property->outputMappedName ?? $property->name;
        
        // Access transformation context
        $shouldTransformValues = $context->transformValues;
        
        // Perform transformation logic
        return $value;
    }
}
```

## Usage in Rule Inferrers

```php theme={null}
use Spatie\LaravelData\Support\DataProperty;
use Spatie\LaravelData\Support\Validation\PropertyRules;
use Spatie\LaravelData\Support\Validation\ValidationContext;
use Spatie\LaravelData\Support\Validation\RuleInferrer;

class CustomRuleInferrer implements RuleInferrer
{
    public function handle(
        DataProperty $property,
        PropertyRules $rules,
        ValidationContext $context
    ): PropertyRules {
        // Access property information
        $propertyName = $property->name;
        $propertyType = $property->type;
        
        // Access validation context
        $payload = $context->payload;
        $validationPath = $context->validationPath;
        
        // Add rules based on property analysis
        if ($property->type->isNullable) {
            $rules->add(new Nullable());
        }
        
        return $rules;
    }
}
```