@graphql-directive/validator - npm

Validator.js Directives

A validator.js wrapper for GraphQL validation directive

Validation directive Example: @validate(method: METHOD[, OPTIONS]) is used to validate input values of GraphQL fields against specific rules defined in the directive.

import val from "@graphql-directive/validator"
import { makeExecutableSchema } from "@graphql-tools/schema"
import { ApolloServer } from "@apollo/server";
import { startStandaloneServer } from "@apollo/server/standalone"

const typeDefs = `
    input UserInput {
        name: String!       @validate(method: LENGTH, max: 150)
        email: String!      @validate(method: EMAIL)
        dateOfBirth: Date!  @validate(method: BEFORE)
    }
    type Mutation { 
        addUser(user:UserInput!): Boolean!
    }
`

const schema = val.transform(makeExecutableSchema({
    typeDefs: [val.typeDefs, typeDefs],
    resolvers: { /* resolvers */ }
}))

const server = new ApolloServer({ schema })
const { url } = await startStandaloneServer(server)
console.log(`Server running at ${url}`)

Validation Result

For each failed validation, server will throw GraphQLError with message USER_INPUT_ERROR. The detail error message can be seen in extension.error property like below.

{
  "data": {},
  "errors": [
    {
      "message": "USER_INPUT_ERROR",

      /*  ....  */

      "extensions": {
        "error": [
          {
            "message": "Must have a length within the specified range",
            "path": "addUser.user.name"
          },
          {
            "message": "Must be a valid email address",
            "path": "addUser.user.email"
          }
        ],
        "code": "INTERNAL_SERVER_ERROR",
        "stacktrace": [ ]
      }
    }
  ]
}

Custom Error Message

Currently its possible to create your own error message by providing the message on message parameter like example below.

@validate(method: EMAIL, message: "Please provide a valid email address")

Validation Methods

The validation directive supports all of the validation functions in Validator.js. Below is a list of the supported methods and their respective parameters.

Custom Valdiation

You can define your own custom validation logic by registering it on the transform function. First create your own custom validation logic with plugin

const customValidators: Plugins = {
    phone: (val) => /^(\()?\d{3}(\))?(-|\s)?\d{3}(-|\s)\d{4}$/.test(val) || "Invalid phone number"
}

Keep in mind that the name (phone) will be used to identify the plugin. Next step, register the plugin into the transformer.

const schema = val.transform(/* executable schema*/, { customValidators })

The final process, apply it on the @validate directive like below

input UserInput {
    phone: String!  @validate(method: CUSTOM, validator: "phone")
}