apollo-server-constraint-directive

Allows using @constraint as a directive to validate input and output data. This module is for Apollo Server, and support the latest Apollo Server version 2.

It is mainly based on the module from graphql-constraint-directive, which is for Apollo version 1 only. This module is an Inspired by Constraints Directives RFC and OpenAPI

If you are looking for a playground checkout this project apollo-server-playground.

Install

npm install apollo-server-constraint-directive

Usage

const { ApolloServer, makeExecutableSchema, gql } = require('apollo-server')
const ConstraintDirective = require('apollo-server-constraint-directive')

const schemaDirectives = {
  constraint: ConstraintDirective,
};

const typeDefs = gql`
  scalar ValidateString
  scalar ValidateNumber

  directive @constraint(
    # String constraints
    minLength: Int
    maxLength: Int
    startsWith: String
    endsWith: String
    notContains: String
    pattern: String
    format: String

    # Number constraints
    min: Int
    max: Int
    exclusiveMin: Int
    exclusiveMax: Int
    multipleOf: Int
  ) on INPUT_FIELD_DEFINITION
  
  type Query {
    books: [Book]
  }
  type Book {
    title: String
  }
  type Mutation {
    createBook(input: BookInput): Book
  }
  input BookInput {
    title: String! @constraint(minLength: 5, format: "email")
  }`

// The ApolloServer constructor
const server = new ApolloServer({
  schema: makeExecutableSchema({ typeDefs, schemaDirectives })
})

// The `listen` method launches a web server.
server.listen().then(({ url }) => {
  console.log(`🚀  Server ready at ${url}`)
})

API

String

minLength

@constraint(minLength: 5) Restrict to a minimum length

maxLength

@constraint(maxLength: 5) Restrict to a maximum length

startsWith

@constraint(startsWith: "foo") Ensure value starts with foo

endsWith

@constraint(endsWith: "foo") Ensure value ends with foo

contains

@constraint(contains: "foo") Ensure value contains foo

notContains

@constraint(notContains: "foo") Ensure value does not contain foo

pattern

@constraint(pattern: "^[0-9a-zA-Z]*$") Ensure value matches regex, e.g. alphanumeric

format

@constraint(format: "email") Ensure value is in a particular format

Supported formats:

• byte: Base64
• date-time: RFC 3339
• date: ISO 8601
• email
• ipv4
• ipv6
• uri
• uuid

password strength

@constraint(passwordScore: 3) Ensure password value has estimated strength. zxcvbn is used under the hood. Possible strength values are between 1 and 5. Heigher is better

Int/Float

min

@constraint(min: 3) Ensure value is greater than or equal to

max

@constraint(max: 3) Ensure value is less than or equal to

exclusiveMin

@constraint(exclusiveMin: 3) Ensure value is greater than

exclusiveMax

@constraint(exclusiveMax: 3) Ensure value is less than

multipleOf

@constraint(multipleOf: 10) Ensure value is a multiple

ConstraintDirectiveError

Each validation error throws a ConstraintDirectiveError. Combined with a formatError function, this can be used to customise error messages.

{
  code: 'ERR_GRAPHQL_CONSTRAINT_VALIDATION',
  fieldName: 'theFieldName',
  context: [ { arg: 'argument name which failed', value: 'value of argument' } ]
}

const formatError = function (error) {
  if (error.originalError && error.originalError.code === 'ERR_GRAPHQL_CONSTRAINT_VALIDATION') {
    // return a custom object
  }
  return error
}

const apollo = new ApolloServer({
  schema: makeExecutableSchema({ typeDefs, schemaDirectives }),
  formatError
});