graphql-constraint-directive


Allows using @constraint as a directive to validate input data. Inspired by Constraints Directives RFC and OpenAPI

Install

``
npm install graphql-constraint-directive
`

Usage

`js
const { constraintDirective, constraintDirectiveTypeDefs } = require('graphql-constraint-directive')
const express = require('express')
const { ApolloServer } = require('apollo-server-express')
const { makeExecutableSchema } = require('graphql-tools')
const typeDefs =
type Query {
books: [Book]
}
type Book {
title: String
}
type Mutation {
createBook(input: BookInput): Book
}
input BookInput {
title: String! @constraint(minLength: 5, format: "email")
}
const schema = makeExecutableSchema({
typeDefs: [constraintDirectiveTypeDefs, typeDefs],
schemaTransforms: [constraintDirective()]
})
const app = express()
const server = new ApolloServer({ schema })

server.applyMiddleware({ app })

`

API

$3

#### 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

#### oneOf
`@constraint(oneOf: ['test', 'hello'])`
Value should be equal to one of the strings supplied

$3

#### 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

$3

#### minListLength
`@constraint(minListLengt: 10)`
Ensure list length is greater than

#### maxListLength
`@constraint(maxListLengt: 10)`
Ensure list length is less than

$3

Each validation error throws a ConstraintDirectiveError. Combined with a formatError function, this can be used to customise error messages.
`js
{
code: 'ERR_GRAPHQL_CONSTRAINT_VALIDATION',
fieldName: 'theFieldName',
context: [ { arg: 'argument name which failed', value: 'value of argument' } ]
}
`

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

return error
}

app.use('/graphql', bodyParser.json(), graphqlExpress({ schema, formatError }))

`

$3

`@constraint(uniqueTypeName: "Unique_Type_Name")``
Override the unique type name generate by the library to the one passed as an argument