Input Object Type Definition

The GraphQL specification defines the Input Object type for complex inputs. It is similar to the Object type, but its fields have no args or resolve options and their type must be input type.

Writing Input Object Types

In graphql-php, Input Object Type is an instance of GraphQL\Type\Definition\InputObjectType (or one of its subclasses) which accepts configuration array in its constructor:

use GraphQL\Type\Definition\Type;
use GraphQL\Type\Definition\InputObjectType;

$filters = new InputObjectType([
    'name' => 'StoryFiltersInput',
    'fields' => [
        'author' => [
            'type' => Type::id(),
            'description' => 'Only show stories with this author id'
        ],
        'popular' => [
            'type' => Type::boolean(),
            'description' => 'Only show popular stories (liked by several people)'
        ],
        'tags' => [
            'type' => Type::listOf(Type::string()),
            'description' => 'Only show stories which contain all of those tags'
        ]
    ]
]);

Every field may be of other InputObjectType (thus complex hierarchies of inputs are possible)

Configuration options

The constructor of InputObjectType accepts an array with the following options:

Option	Type	Notes
name	string	Required. Unique name of this object type within Schema
description	string	Plain-text description of this type for clients (e.g. used by GraphiQL for auto-generated documentation)
isOneOf	bool	Indicates that an Input Object is a OneOf Input Object (and thus requires exactly one of its fields be provided).
parseValue	callable(array<string, mixed>): mixed	Converts incoming values from their array representation to something else (e.g. a value object)
fields	iterable<FieldConfig> or callable(): iterable<FieldConfig>	Required. An iterable describing object fields or callable returning such an iterable (see below).

Every entry in fields is an array with following entries:

Option	Type	Notes
name	string	Required. Name of the input field. When not set - inferred from fields array key
type	Type	Required. Instance of one of Input Types (Scalar, Enum, InputObjectType + any combination of those with nonNull and listOf modifiers)
defaultValue	scalar	Default value of this input field. Use the internal value if specifying a default for an enum type
description	string	Plain-text description of this input field for clients (e.g. used by GraphiQL for auto-generated documentation)
deprecationReason	string	Plain-test reason for why this input field is deprecated.

Using Input Object Type

In the example above we defined our InputObjectType StoryFiltersInput. Now let's use it in one of field arguments:

use GraphQL\Type\Definition\Type;
use GraphQL\Type\Definition\ObjectType;

$queryType = new ObjectType([
    'name' => 'Query',
    'fields' => [
        'stories' => [
            'type' => Type::listOf($storyType),
            'args' => [
                'filters' => [
                    'type' => $filters,
                    'defaultValue' => [
                        'popular' => true,
                    ],
                ],
            ],
            'resolve' => fn ($rootValue, array $args): array => DataSource::filterStories($args['filters']),
        ],
    ],
]);

You can define defaultValue for fields with complex inputs as an associative array.

Then GraphQL query could include filters as a literal value:

{
  stories(filters: {
    author: "1"
    popular: false
  }) {
    ...
  }
}

Or as a query variable:

query ($filters: StoryFiltersInput!) {
  stories(filters: $filters) {
    ...
  }
}

{
  "filters": {
    "author": "1",
    "popular": false
  }
}

graphql-php will validate the input against your InputObjectType definition and pass it to your resolver as $args['filters'].

Converting Input Array to Value Object

If you want more type safety you can choose to parse the input array into a value object.

use GraphQL\Type\Definition\Type;
use GraphQL\Type\Definition\InputObjectType;

final readonly class StoryFiltersInput
{
    public function __construct(
        public string $author,
        public ?bool $popular,
        /** @var array<string> */
        public array $tags
    ) {}
}

$filters = new InputObjectType([
    'name' => 'StoryFiltersInput',
    'fields' => [
        'author' => [
            'type' => Type::nonNull(Type::string()),
        ],
        'popular' => [
            'type' => Type::boolean(),
        ],
        'tags' => [
            'type' => Type::nonNull(Type::listOf(Type::string())),
        ]
    ],
    'parseValue' => fn (array $values): StoryFiltersInput => new StoryFiltersInput(
        author: $values['author'],
        popular: $values['popular'] ?? null,
        tags: $values['tags'],
    ),
]);

The value of $args['filters'] will now be an instance of StoryFiltersInput.

The incoming values are converted using a depth-first traversal. Thus, nested input values will be passed through their respective parseValue functions before the parent receives their value.

Using the isOneOf Configuration Option

The isOneOf configuration option allows you to declare an input object as a OneOf Input Object. This means that exactly one of its fields must be provided when the input is used. This is useful when an argument can accept several alternative values, but never more than one at the same time.

Suppose you want to allow a query to filter stories either by author or by tag, but not both together. You can define an input object with isOneOf: true:

use GraphQL\Type\Definition\Type;
use GraphQL\Type\Definition\InputObjectType;

$storySearch = new InputObjectType([
    'name' => 'StorySearchInput',
    'isOneOf' => true,
    'fields' => [
        'author' => [
            'type' => Type::id(),
            'description' => 'Find stories by a specific author',
        ],
        'tag' => [
            'type' => Type::string(),
            'description' => 'Find stories with a specific tag',
        ],
    ],
]);

This input object can then be used as an argument in a query:

$searchType = new ObjectType([
    'name' => 'Query',
    'fields' => [
        'searchStories' => [
            'type' => Type::listOf($storyType),
            'args' => [
                'search' => [
                    'type' => $storySearch,
                ],
            ],
            'resolve' => fn ($rootValue, array $args): array => DataSource::searchStories($args['search']),
        ],
    ],
]);

{
  searchStories(search: { author: "1" }) {
    id
    title
  }
}

If you try to provide both fields at once, validation will fail:

{
  searchStories(search: { author: "1", tag: "php" }) {
    id
    title
  }
}

graphql-php ensures that with isOneOf: true, exactly one field is set. This helps make APIs clearer and less error-prone when alternative inputs are required.