nexus-validate

!build-publish

Add extra validation to GraphQL Nexus in an easy and expressive way.

``ts
const UserMutation = extendType({
type: 'Mutation',
definition(t) {
t.field('createUser', {
type: 'User',

// add arguments
args: {
email: stringArg(),
age: intArg(),
},

// add the extra validation
validate: ({ string, number }) => ({
email: string().email(),
age: number().moreThan(18).integer(),
}),
});
},
});
`

Documentation

- Installation
- Usage
- Custom validations
- Custom errors
- Custom error messages
- API
- Examples

Installation

`console


npm

npm i nexus-validate yup

yarn

yarn add nexus-validate yup
`

> nexus-validate uses yup under the hood so you need to install that too. nexus and graphql are also required, but if you are using Nexus then both of those should already be installed.

$3

Once installed you need to add the plugin to your nexus schema configuration:

`ts
import { makeSchema } from 'nexus';
import { validatePlugin } from 'nexus-validate';

const schema = makeSchema({
...
plugins: [
...
validatePlugin(),
],
});
`

Usage

The validate method can be added to any field with args:

`ts
const UserMutation = extendType({
type: 'Mutation',
definition(t) {
t.field('createUser', {
type: 'User',
args: {
email: stringArg(),
},
validate: ({ string }) => ({
// validate that email is an actual email
email: string().email(),
}),
});
},
});
`

Trying to call the above with an invalid email will result in the following error:

`json
{
"errors": [
{
"message": "email must be a valid email",
"extensions": {
"invalidArgs": ["email"],
"code": "BAD_USER_INPUT"
}
...
}
]
}
`

$3

If you don't want to use the built-in validation rules, you can roll your own by throwing an error if an argument is invalid, and returning void if everything is OK.

`ts
import { UserInputError } from 'nexus-validate';
t.field('createUser', {
type: 'User',
args: {
email: stringArg(),
},
// use args and context to check if email is valid
validate(_, args, context) {
if (args.email !== context.user.email) {
throw new UserInputError('not your email', {
invalidArgs: ['email'],
});
}
},
});
`

$3

The plugin provides a formatError option where you can format the error however you'd like:

`ts
import { UserInputError } from 'apollo-server';
import { validatePlugin, ValidationError } from 'nexus-validate';

const schema = makeSchema({
...
plugins: [
...
validatePlugin({
formatError: ({ error }) => {
if (error instanceof ValidationError) {
// convert error to UserInputError from apollo-server
return new UserInputError(error.message, {
invalidArgs: [error.path],
});
}

return error;
},
}),
],
});
`

$3

If you want to change the error message for the validation rules, that's usually possible by passing a message to the rule:

`ts
validate: ({ string }) => ({
email: string()
.email('must be a valid email address')
.required('email is required'),
});
`

API

##### validate(rules: ValidationRules, args: Args, ctx: Context) => Promise

$3

| Type | Docs | Example |
| :------ | :--------------------------------------------- | :----------------------------------------- |
| string | docs | string().email().max(20).required() |
| number | docs | number().moreThan(18).number() |
| boolean | docs | boolean() |
| date | docs | date().min('2000-01-01').max(new Date()) |
| object | docs | object({ name: string() }) |
| array | docs | array.min(5).of(string()) |

$3

The Args argument will return whatever you passed in to args in your field definition:

`ts
t.field('createUser', {
type: 'User',
args: {
email: stringArg(),
age: numberArg(),
},
// email and age will be typed as a string and a number
validate: (_, { email, age }) => {}
}
`

$3

Context is your GraphQL context, which can give you access to things like the current user or your data sources. This will let you validation rules based on the context of your API.

`ts
t.field('createUser', {
type: 'User',
args: {
email: stringArg(),
},
validate: async (_, { email }, { prisma }) => {
const count = await prisma.user.count({ where: { email } });
if (count > 1) {
throw new Error('email already taken');
}
},
});
``

Examples

- Hello World Example

License

nexus-validate is provided under the MIT License. See LICENSE for details.