Validation

Validating Arguments

Lighthouse allows you to use Laravel's validation (opens new window) for your queries and mutations. The simplest way to leverage the built-in validation rules is to use the @rules directive.

type Mutation {
  createUser(
    name: String @rules(apply: ["required", "min:4"])
    email: String @rules(apply: ["email"])
  ): User
}

In the case of a validation error, Lighthouse will abort execution and return the validation messages as part of the response.

mutation {
  createUser(email: "hans@peter.xyz") {
    id
  }
}

{
  "data": {
    "createUser": null
  },
  "errors": [
    {
      "message": "Validation failed for the field [createUser].",
      "locations": [
        {
          "line": 2,
          "column": 13
        }
      ],
      "extensions": {
        "validation": {
          "email": ["The email field must be a valid email."]
        }
      }
    }
  ]
}

You can customize the error message for a particular argument.

@rules(apply: ["max:140"], messages: { max: "Tweets have a limit of 140 characters"})

Validating For Uniqueness

Using the unique (opens new window) validation rule can be a bit tricky.

If the argument is nested within an input object, the argument path will not match the column name, so you have to specify the column name explicitly.

input CreateUserInput {
  email: String @rules(apply: ["unique:users,email_address"])
}

Validating Arrays

When you are passing in an array as an argument to a field, you might want to apply some validation on the array itself, using @rulesForArray

type Mutation {
  makeIcecream(topping: [Topping!]! @rulesForArray(apply: ["max:3"])): Icecream
}

You can also combine this with @rules to validate both the size and the contents of an argument array. For example, you might require a list of at least 3 valid emails to be passed.

type Mutation {
  attachEmails(
    email: [String!]! @rules(apply: ["email"]) @rulesForArray(apply: ["min:3"])
  ): File
}

Using Custom Validation Rules

You can use custom validation rules (opens new window) by passing class name.

type Mutation {
  createUser(
    name: String @rules(apply: "required", "App\\Rules\\MyCustomRule")
    email: String @rules(apply: "required", "email", "unique:users,email")
    password: String @rules(apply: "required", "min:5") @bcrypt
   ): User
}