Playing with GraphQL

This project was created following the excellent tutorials at howtographql.com

Blog post: Comparing REST and GraphQL

Setup

Mongo

You can also setup a local Mongo running from a local Docker image. Pull the Mongo image and run remembering to use the -p option to the port. e.g:

docker run -p 27017:27017 --name some-mongo mongo

Useful connecting to the Mongo shell during development viewing contents of collections etc:

docker exec -it some-mongo bash

Application startup

mvn jetty:run

using GraphiQL browser client

http://localhost:8080

Example requests

Example requests that can be used with GraphiQL browser test client.

# query request - User

query users{
    getUsers{
        id
        name
    }
}

# query request - Link

query links{
    allLinks{
        url
        description
    }
}

# query request with filterng - Link

query links{
    allLinks(filter:{description_contains: "ppl", url_contains: "bbc"}){
        url
        description
    }
}

# query request with pagination - Link
query links{
    allLinks(skip: 1, first: 1){
        url
        description
    }
}

# mutation request create - Link
mutation createLink{
    createLink(url:"http://guardian.co.uk", description: "Not that much better"){
        url
        description
    }
}

# mutation request create - User
mutation createUser{
    createUser(
        name: "dude"
        authProvider: {
            email: "dude@gmail.com"
            password: "secret"
        }){
        id
        name
    }
}

# mutation request authentication
mutation signIn{
    signinUser(auth:{email: "dude@gmail.com", password:"secret"}){
        token
        user{
            id
            name
        }
    }
}

# mutation request create - Vote
mutation vote{
    createVote(linkId: "????"
               userId: "????"
    ){
        createdAt
        link{
            url
        }
        user {
            name
        }
    }
}

GraphQL features

• one endpoint

• backed by a schema which can be introspected by clients

• declarative style queries by clients to get exactly the data it wants

• notes:

  • pretty cool idea but early technology
  • declarative like SQL but unlike SQL, many features missing no inbuilt support for filtering, pagination style queries. Backend needs to invent SQL engine features if features desired.
  • extra effort is needed to guard against malicious queries.
  • cannot easily cache queries as REST due to the dynamic nature of client requests
  • since GraphQL can be used with any transport protocol cannot use OAuth or even Basic HTTP Authentication. Again need to invent into the schema itself.
  • efficient data collection is probably the most difficult to achieve. That is like trying to reinvent a DBMS