GraphQL - Herbs2GQL

Creates GraphQL types (queries, mutations, etc.) based on herbs entities and usecases, based on Apollo GraphQL.

Getting started

Installing

$ npm install @herbsjs/herbs2gql

Using

If your project uses Herbarium as discovery service you can generate mutations, queries and types with less code.

const { herbarium } = require('@herbsjs/herbarium')
const { herbs2gql } = require('@herbsjs/herbs2gql')

const { mutations, queries, types } = herbs2gql(herbarium)

Advanced Features

All methods returns a string in GraphQL format representing the type based (gql) and a resolver (when expected).

const { entity, field, id } = require('@herbsjs/herbs')
const { entity2type } = require('@herbsjs/herbs2gql')

const user = entity('User', {
    id: id(String),
    name: field(String),
    document: field(String),
    age: field(Number),
    active: field(Boolean),
})

const gql = entity2type(user)
console.log(gql)
/* Result
type User {
    id: String
    name: String
    document: String
    age: Float
    active: Boolean
}
*/

GraphQL Type

To convert a Herbs Entity to GraphQL Type:

const entity = entity('User', {
    id: id(String),
    name: field(String),
    document: field(String),
    age: field(Number),
    active: field(Boolean),
})

const gql = entity2type(entity)

GraphQL Input

To convert a Herbs Entity to GraphQL Input:

const entity = entity('UserFilter', {    
    name: field(String),    
    age: field(Number),    
})

const gql = entity2input(entity)

GraphQL Query

To convert a Herbs Use Case to GraphQL Query:

const usecase = usecase('Get User', {
    request: {
        id: Number,
        document: String
    },

    response: User
})

const resolverFunc = (parent, args, context, info) => { }

const [gql, resolver] = usecase2query(usecase, resolverFunc)

GraphQL Mutation

To convert a Herbs Use Case to GraphQL Mutation:

const usecase = usecase('Update User', {
    request: {
        id: Number,
        name: String,
        age: Number,
        active: Boolean
    },

    response: User
})

const resolverFunc = (parent, args, context, info) => { }

const [gql, resolver] = usecase2mutation(usecase, resolverFunc)

GraphQL Subscription

To convert a Herbs Use Case to GraphQL Subscription:

const usecase = usecase('New User Notification', {
    request: {
        id: Number,        
    },

    response: UserMessage
})

const resolverFunc = () => { }

const [gql, resolver] = usecase2subscription(usecase, resolverFunc)

Custom Names or Conventions

In Herbs it is possible to include personalized names for queries, mutations, inputs and types custom names are always prioritized

Custom Names

const options = { inputName: 'An-Entity' }

// for entity2input
const gql = entity2input(givenAnInput, options)

// for entity2type
const gql = entity2type(givenAnEntity, options)

//for mutation, query or subscription example using mutation
const [gql, resolver] = usecase2mutation(givenAUseCase, resolverFunc, options)

Conventions

At the convention, a function must be sent, it must return a text formatted according to the sended convention

const options = { convention: { inputNameRule: (str) => `snake_case_returned` }}

// for entity2input
const gql = entity2input(givenAnInput, options)

// for entity2type
const gql = entity2type(givenAnEntity, options)

//for mutation, query or subscription example using mutation
const [gql, resolver] = usecase2mutation(givenAUseCase, resolverFunc, options)

Apollo Errors and Err

herbs2gql deals with errors in the default resolver. It translates the usecase's errors into graphql errors:

Usecase Error	Apollo Error
Permission Denied	ForbiddenError
Not Found	ApolloError
Already Exists	ApolloError
Unknown	ApolloError
Invalid Arguments	UserInputError
Invalid Entity	UserInputError
Any other kind of errors	UserInputError

However, it's behavior can be overridden in the errorHandler property of the options parameter:

const { defaultResolver } = require("@herbsjs/herbs2gql")

const myCustomErrorHandler = (usecaseResponse) => {
  // handle the errors on your own way
}

const options = {
  errorHandler: myCustomErrorHandler,
}

const updateUser = usecase("Update User", {
  // usecase implementation
})

const [gql, resolver] = usecase2mutation(
  updateUser(),
  defaultResolver(updateUser, options)
)

Your custom error handler can also utilize the defaultErrorHandler as a fallback:

const { defaultResolver, defaultErrorHandler } = require("@herbsjs/herbs2gql")

const myCustomErrorHandler = (usecaseResponse) => {
  // handle the errors on your own way

  // use the default error handler when there is no need of a specific treatment
  return defaultErrorHandler(usecaseResponse)
}

const options = {
  errorHandler: myCustomErrorHandler,
}

const updateUser = usecase("Update User", {
  // usecase implementation
})

const [gql, resolver] = usecase2mutation(
  updateUser(),
  defaultResolver(updateUser, options)
)

The Known Errors​ are described in the documentation.

Example

Additionally you can view a simple demo application of this library in todolist-on-herbs.