README

GraphQL is great when it comes to validating types and checking syntax, but isn't much help when it comes to providing additional validation on user input. The authors of GraphQL have generally opined that the correct response to bad user input is not to throw an exception, but rather to return any validation feedback along with the result.

As Lee Byron explains here:

...allow for data for a user-facing report in the payload of your mutation. It's often the case that mutation payloads include a "didSucceed" field and a "userError" field. If your UI requires rich information about potential errors, then you should include this information in your payload as well.

That's where this small library comes in.

graphql-php-validation-toolkit extends the built-in definitions provided by the wonderful graphql-php library with a new ValidatedFieldDefinition class. Simply instantiate one of these in place of the usual field config, add validate callback properties to your args definitions, and the type of your field will be replaced by a new, dynamically-generated ResultType with queryable error fields for each of your args. It's a recursive process, so your args can have InputObjectType types with subfields and validate callbacks of their own. Your originally-defined type gets moved to the result field of the generated type.

Installation

Via composer:

composer require shmax/graphql-php-validation-toolkit

Basic Usage

In a nutshell, replace your usual vanilla field definition with an instance of ValidatedFieldDefinition, and add validate callbacks to one or more of the args configs. Let's say you want to make a mutation called updateBook:

//...
'updateBook' => new ValidatedFieldDefinition([
   'name' => 'updateBook',
   'type' => Types::book(),
   'args' => [
       'bookId' => [
           'type' => Type::id(),
           'validate' => function ($bookId) {
               global $books;
               if (!Book::find($bookId) {
                   return 0;
               }

               return [1, 'Unknown book!'];
           },
       ],
   ],
   'resolve' => static function ($value, $args) : bool {
       return Book::find($args['bookId']);
   },
],

In the sample above, the book type property of your field definition will be replaced by a new dynamically-generated type called UpdateBookResultType.

The type generation process is recursive, traveling down through any nested InputObjectType or ListOf types and checking their fields for more validate callbacks. Every field definition--including the very top one--that has a validate callback will be represented by a custom, generated type with the following queryable fields:

Field	Type	Description
`code`	`int` \| `<field-name>ErrorCode`	This will resolve to `0` for a valid field, otherwise `1`. If `errorCodes` were provided, then this will be a custom generated Enum type.
`msg`	`string`	A plain, natural language description of the error.
`suberrors`	`<field-name>_Suberrors`	A `suberrors` field will be added to a generated field of type `InputObjectType` if any of the following are true: It is the root node The field has a `validate` method The `InputObjectType` is wrapped in a `ListOfType`

The top-level <field-name>ResultType will have a few additional fields:

Field	Type	Description
`valid`	`bool`	Resolves to `true` if all `args` and nested `fields` pass validation, `false` if not.
`result`	`mixed`	This is the original `type` you provided when declaring your field. Eg, If you specified `type` to be a `Book`, then the type of `result` will be `Book`.

You can then simply query for these fields along with result:

mutation {
    updateAuthor(
        authorId: 1
  ) {
    valid
    result {
        id
        name
    }
    code
    msg
    suberrors {
        authorId {
            code
            msg
        }
    }
  }
}

The Validate Callback

Any field definition can have a validate callback. The first argument passed to the validate callback will be the value to validate. If the value is valid, return 0, otherwise 1.

//...
'updateAuthor' => new ValidatedFieldDefinition([
  'type' => Types::author(),
  'args' => [
    'authorId' => [
      'validate' => function(string $authorId) {
        if(Author::find($authorId)) {
          return 0;
        }
        return 1;
      }
    ]
  ]	  
])

If you want to return an error message, return an array with the message in the second bucket:

//...
'updateAuthor' => new ValidatedFieldDefinition([
  'type' => Types::author(),
  'args' => [
    'authorId' => [
      'validate' => function(string $authorId) {
        if(Author::find($authorId)) {
          return 0;
        }
        return [1, "We can't find that author"];
      }
    ]
  ]	  
])

Generated ListOf error types also have a path field that you can query so you can know the exact address in the multidimensional array of each item that failed validation:

//...
'setPhoneNumbers' => new ValidatedFieldDefinition([
  'type' => Types::bool(),
  'args' => [
    'phoneNumbers' => [
      'type' => Type::listOf(Type::string()),  
      'validate' => function(string $phoneNumber) {
        $res = preg_match('/^[0-9\-]+$/', $phoneNumber) === 1;
        if (!$res) {
          return [1, 'That does not seem to be a valid phone number'];
        }
        return 0;  
      }
    ]
  ]	  
])

Custom Error Codes

If you would like to use custom error codes, add an errorCodes property at the same level as your validate callback:

//...
'updateAuthor' => [
  'type' => Types::author(),
  'errorCodes' => [
    'authorNotFound`
  ],
  'validate' => function(string $authorId) {
    if(Author::find($authorId)) {
      return 1;
    }
    return ['authorNotFound', "We can't find that author"];
  }
]

Managing Created Types

This library will create new types as needed. If you are using some kind of type manager to store and retrieve types, you can integrate it by providing a typeSetter callback:

new ValidatedFieldDefinition([
    'typeSetter' => static function ($type) {
        Types::set($type);
    },
]);

Examples

The best way to understand how all this works is to experiment with it. There are a series of increasingly complex one-page samples in the /examples folder. Each is accompanied by its own README.md, with instructions for running the code. Run each sample, and be sure to inspect the dynamically-generated types in ChromeiQL.

Contribute

Contributions are welcome. Please refer to CONTRIBUTING.md for guidelines.

mpscl / graphql-php-validation-toolkit

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