README

@iksena/graphql-constraint-directive

Allows using @constraint as a directive to validate input data. Inspired by Constraints Directives RFC and OpenAPI
Forked from graphql-constraint-directive to use SchemaDirectiveVisitor and make it compatible with Apollo Federation

Install

npm install @iksena/graphql-constraint-directive

Usage

const { ConstraintDirective, constraintDirectiveTypeDefs } = require('@iksena/graphql-constraint-directive');
const express = require('express');
const { ApolloServer, SchemaDirectiveVisitor, makeExecutableSchema } = require('apollo-server-express');
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]
});
SchemaDirectiveVisitor.visitSchemaDirectives(schema, {
  constraint: ConstraintDirective
});
const app = express();
const server = new ApolloServer({ schema });

server.applyMiddleware({ app });

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]*quot;) 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

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
}

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

uniqueTypeName

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

Usage no npm install needed!