USING GRAPHQL AND RELAY

FOR HYBRID

 RUBY ON RAILS APPLICATIONS

Rubyfuza, Cape Town, South Africa

February 02, 2018

• Brazilian
• Bachelor and Master on Computer Science (UFBA)
• Ruby On Rails since 2008
• http://ca.ios.ba

• Meedan Software Engineer since 2011      
   
• San Francisco - California
   
• http://meedan.com

Check

Social media fact-checking

2012 - today

github.com/meedan/checkdesk

   github.com/meedan/check-api

   github.com/meedan/check-web

   github.com/meedan/lapis

github.com/meedan/generator-keefer

Backend

Frontend

Ruby On Rails template

Yeoman generator

graphql

react.js

relay

ruby on rails

graphql

react.js

relay

ruby on rails

BACKEND

FRONTEND

GraphQL

"GraphQL is a query language for your API, and a server-side runtime for executing queries by using a type system you define for your data"

REST

Media

Comment

Tag

1

*

User

*

*

*

1

GET /api/v1/medias/1
GET /api/v1/medias/1/comments
GET /api/v1/medias/1/tags
GET /api/v1/medias/1/comments/1
GET /api/v1/users/1?fields=avatar,name
GET /api/v1/users/2?fields=avatar,name
GET /api/v1/users/3?fields=avatar,name
...

Reusable endpoints

GET /api/v1/medias/1?include=comments&count=5

GET /api/v1/medias/1?include=comments,tags
    &comments_count=5&tags_count=5

GET /api/v1/medias/1?fields=comments(text,date)
    &tags(tag)


...


GET /api/v1/media_and_comments/1
GET /api/v1/media_comments_and_tags/1
GET /api/v1/media_comments_tags_and_users/1

GET /api/v1/medias/1?include=comments&count=5

GET /api/v1/medias/1?include=comments,tags
    &comments_count=5&tags_count=5

GET /api/v1/medias/1?fields=comments(text,date)
    &tags(tag)


...


GET /api/v1/media_and_comments/1
GET /api/v1/media_comments_and_tags/1
GET /api/v1/media_comments_tags_and_users/1

Too many requests!

GraphQL

One endpoint to rule them all

POST /graphql

POST /api/graphql?query=
{
  media(id: 1) {
    title
    embed
    tags(first: 3) {
      tag
    }
    comments(first: 5) {
      created_at
      text
      user {
        name,
        avatar
      }
    }
  }
}

POST /api/graphql?query=
{
  media(id: 1) {
    title
    embed
    tags(first: 3) {
      tag
    }
    comments(first: 5) {
      created_at
      text
      user {
        name,
        avatar
      }
    }
  }
}

Media

Comment

Tag

1

*

User

*

*

*

1

~

POST /api/graphql?query=
{
  media(id: 1) {
    title
    embed
    tags(first: 3) {
      tag
    }
    comments(first: 5) {
      created_at
      text
      user {
        name,
        avatar
      }
    }
  }
}

{
  "media": {
    "title": "Avangers Hulk Smash",
    "embed": "<iframe src=\"...\"></iframe>",
    "tags": [
      { "tag": "avengers" },
      { "tag": "operation" }
    ],
    "comments": [
      {
        "text": "This is true",
        "created_at": "2016-09-18 15:04:39",
        "user": {
          "name": "Ironman",
          "avatar": "http://[...].png"
        }
      },
      ...
    ]
  }
}

GraphQL

Ruby On Rails

Creating a new Rails API with GraphQL support

$ git clone https://github.com/meedan/lapis.git
$ rails new <name> -m <path to lapis_template.rb>

• No view (headless API)
• REST & GraphQL
• Swagger UI & GraphiQL
• Docker
• Client gem generation
• Webhooks & tokens

Adding GraphQL support to existing application

gem 'graphql'
gem 'graphql-relay'

Gemfile

class GraphqlController < BaseApiController
  def create
    vars = params[:variables] || {}
    query = GraphQL::Query.new(RelayOnRailsSchema, params[:query], variables: vars)
    render json: query.result
  end
end

app/controllers/graphql_controller.rb (add route too)

RelayOnRailsSchema = GraphQL::Schema.new(query: QueryType, mutation: MutationType)

config/initializers/relay.rb

type Media {
  title: String
  embed: String
  user: User
  comments: [Comment]
}

# "Type" to differentiate from models
MediaType = GraphQL::ObjectType.define do
  name 'Media'
  description 'Media type'
  field :title, types.String
  field :embed, types.String
  field :user do
    type UserType
    resolve -> (media, _args, _ctx) {
      media.user
    }
  end
  connection :comments, ->{ CommentType.connection_type }
  do
    argument :user_id, types.Int

    resolve -> (media, args, ctx) {
      media.comments(args[:user_id], ctx[:current_user])
    }
  end
end

Defining a GraphQL type

app/graph/types/media_type.rb

# "Type" to differentiate from models
# MediaType = GraphQL::ObjectType.define do
#   name 'Media'
#   description 'Media type'
    field :title, types.String
    field :embed, types.String
#   field :user do
#     type UserType
#     resolve -> (media, _args, _ctx) {
#       media.user
#     }
#   end
#   connection :comments, ->{ CommentType.connection_type }
#   do
#     argument :user_id, types.Int
#
#     resolve -> (media, args, ctx) {
#       media.comments(args[:user_id], ctx[:current_user])
#     }
#   end
# end

Defining a GraphQL type

By default, fields resolve to model instance methods

# "Type" para diferenciar dos models
# MediaType = GraphQL::ObjectType.define do
#   name 'Media'
#   description 'Media type'
#   field :title, types.String
#   field :embed, types.String
#   field :user do
#     type UserType
#     resolve -> (media, _args, _ctx) {
#       media.user
#     }
#   end
 connection :comments, ->{ CommentType.connection_type } 
 do
   argument :user_id, types.Int

   resolve -> (media, args, ctx) {
     media.comments(args[:user_id], ctx[:current_user])
   }
 end
# end

Defining a GraphQL type

Relationships reference connections of other GraphQL types, can receive arguments and have access to the context

Mutations

mutation { 
  createMedia(
    input: {
      url: "http://youtu.be/7a_insd29fk"
      clientMutationId: "1"
    }
   )
   {
     media {
       id
     }
   }
}

Mutations make changes on your server side.

CRUD:

Queries: Read

Mutations:

• Create
• Update
• Delete

# mutation { 
     createMedia(
#     input: {
        url: "http://youtu.be/7a_insd29fk"
#       clientMutationId: "1"
#     }
#    )
     {
       media {
         id
       }
     }
# }

Mutation name

Input parameters

Desired output

CreateMedia = GraphQL::Relay::Mutation.define do
  input_field :url, !types.String

  return_field :media, MediaType

  resolve -> (inputs, ctx) {
    media = Media.new
    media.url = inputs[:url]
    media.save!
  }
end

On Rails, a mutation must define the input fields, return fields and a resolution method (what the mutation actually does)

React.js

Another JavaScript framework?

var MediaController = new Controller({
  addComment: function(comment) {
    // REST request
  },

  deleteComment: function(commentId) {
    // REST request
  },

  addTag: function(tag) {
    // REST request
  }
});

var MediaController = new Controller({
  addComment: function(comment) {
    // REST request
  },

  deleteComment: function(commentId) {
    // REST request
  },

  addTag: function(tag) {
    // REST request
  }
});

<div class="media">
  <h2>{{media.title}}</h2>
  <ul class="tags">
    <li ng-repeat="tag in tags">{{tag.tag}}</li>
  <ul>
  <ul class="comments">
    <li ng-repeat="comment in comments">
      <div ng-include="partials/comment.html">
    </li>
  <ul>
</div>

var MediaController = new Controller({
  addComment: function(comment) {
    // REST request
  },

  deleteComment: function(commentId) {
    // REST request
  },

  addTag: function(tag) {
    // REST request
  }
});

<div class="media">
  <h2>{{media.title}}</h2>
  <ul class="tags">
    <li ng-repeat="tag in tags">{{tag.tag}}</li>
  <ul>
  <ul class="comments">
    <li ng-repeat="comment in comments">
      <div ng-include="partials/comment.html">
    </li>
  <ul>
</div>

this.$el.find('#delete-comment')
.on('click', function() {
  // call deleteComment
});

MediaComponent

CommentsComponent

TagsComponent

TagComponent

CommentComponent

CommentComponent

CommentComponent

Concerns Separation


Components Separation

x

Self-contained components:

• Testable
• Composable
• Reusable
• Maintainable

import React, { Component, PropTypes } from 'react';
import Relay from 'react-relay';
import DeleteTagMutation from './DeleteTagMutation';

class Tag extends Component {
  delete() {
    const id = this.props.tag.id;
    Relay.Store.commitUpdate(
      new DeleteTagMutation({
        id: id
      })
    );
  }

  render() {
    const tag = this.props.tag;

    return (
      <div className="tag">
        <span>{tag.tag}</span>
        <span onClick={this.delete.bind(this)}>
          x
        </span>
      </div>
    );
  }
}

export default Tag;

RULE #2: React rebuilds everything on every change

Sounds costly? But it's fast!

Virtual DOM

• Creates a light description of the interface
• Calculates the difference between the current state and the previous one
• Computes the minimum number of changes to be applied
• Runs all operations in batch

// import React, { Component, PropTypes } from 'react';
// import Relay from 'react-relay';
// import DeleteTagMutation from './DeleteTagMutation';
//
// class Tag extends Component {
//   handleDelete() {
       const id = this.props.tag.id;
       this.setState({ deleted: true });
//     Relay.Store.commitUpdate(
//       new DeleteTagMutation({
//         id: id
//       })
//     );
//   }
// 
//   render() {
      const tag = this.props.tag;

      if (this.state.deleted) {
        return (<span>Deleted</span>);
      }
//
//    componentWillMount() {
//      this.sort();
//    }
//
//    return (
//      <div className="tag">
//        <span>{tag.tag}</span>
//        <span onClick={this.delete.bind(this)}>
//        x
//        </span>
//      </div>
//    );
//  }
// }
//
// export default Tag;

props

Immutable

state

Mutable

class Tags extends Component {
  render() {
    return (
      <ul className="tags-list">
        {props.tags.map(function(tag) {
          return (
            <Tag tag={tag}>
          );
        })}
      </ul>
    );
  }
}

React Native

class Tags extends Component {
  render() {
    return (
      <ul className="tags-list">
        {props.tags.map(function(tag) {
          return (
            <Tag tag={tag}>
          );
        })}
      </ul>
    );
  }
}

React component

React.js

DOM

React Native

Android

iOS

https://github.com/necolas/react-native-web

Relay

Relay

GraphQL

React.js

React.js + Relay

• React component
• Relay container
• Relay container sends GraphQL data to React component through props

• Only new data is requested
• Queries are validated locally first
• Queries are made to local cache first
  • Relay Store

Mutations

class CreateTagMutation extends Relay.Mutation {
  getMutation() {
    return Relay.QL`mutation createTag {
      createTag
    }`;
  }

  getFatQuery() {
    return Relay.QL`fragment on CreateTagPayload
    { tagEdge, media { tags } }`;
  }

  getVariables() {
    const media = this.props.media;
    return { tag: media.tag.tag, media_id: media.id };
  }

  getConfigs() {
    return [{
      type: 'RANGE_ADD',
      parentName: 'media',
      parentID: this.props.media.id,
      connectionName: 'tags',
      edgeName: 'tagEdge',
      rangeBehaviors: {
        '': 'append'
      }
    }];
  }
}

// class CreateTagMutation extends Relay.Mutation {
     getMutation() {
       return Relay.QL`mutation createTag {
         createTag
       }`;
     }
// 
//   getFatQuery() {
//     return Relay.QL`fragment on CreateTagPayload
//     { tagEdge, media { tags } }`;
//   }
// 
//   getVariables() {
//     const media = this.props.media;
//     return { tag: media.tag.tag, media_id: media.id };
//   }
// 
//   getConfigs() {
//     return [{
//       type: 'RANGE_ADD',
//       parentName: 'media',
//       parentID: this.props.media.id,
//       connectionName: 'tags',
//       edgeName: 'tagEdge',
//       rangeBehaviors: {
//         '': 'append'
//       }
//     }];
//   }
// }

Mutation to be called

Expected return

Input parameters

How to update local cache

// class CreateTagMutation extends Relay.Mutation {
//   getMutation() {
//     return Relay.QL`mutation createTag {
//       createTag
//     }`;
//   }
// 
     getFatQuery() {
       return Relay.QL`fragment on CreateTagPayload
       { tagEdge, media { tags } }`;
     }
// 
//   getVariables() {
//     const media = this.props.media;
//     return { tag: media.tag.tag, media_id: media.id };
//   }
// 
//   getConfigs() {
//     return [{
//       type: 'RANGE_ADD',
//       parentName: 'media',
//       parentID: this.props.media.id,
//       connectionName: 'tags',
//       edgeName: 'tagEdge',
//       rangeBehaviors: {
//         '': 'append'
//       }
//     }];
//   }
// }

Mutation to be called

Expected return

Input parameters

How to update local cache

// class CreateTagMutation extends Relay.Mutation {
//   getMutation() {
//     return Relay.QL`mutation createTag {
//       createTag
//     }`;
//   }
// 
//   getFatQuery() {
//     return Relay.QL`fragment on CreateTagPayload
//     { tagEdge, media { tags } }`;
//   }
// 
     getVariables() {
       const media = this.props.media;
       return { tag: media.tag.tag, media_id: media.id };
     }
// 
//   getConfigs() {
//     return [{
//       type: 'RANGE_ADD',
//       parentName: 'media',
//       parentID: this.props.media.id,
//       connectionName: 'tags',
//       edgeName: 'tagEdge',
//       rangeBehaviors: {
//         '': 'append'
//       }
//     }];
//   }
// }

Mutation to be called

Expected return

Input parameters

How to update local cache

// class CreateTagMutation extends Relay.Mutation {
//   getMutation() {
//     return Relay.QL`mutation createTag {
//       createTag
//     }`;
//   }
// 
//   getFatQuery() {
//     return Relay.QL`fragment on CreateTagPayload
//     { tagEdge, media { tags } }`;
//   }
// 
//   getVariables() {
//     const media = this.props.media;
//     return { tag: media.tag.tag, media_id: media.id };
//   }
// 
     getConfigs() {
       return [{
         type: 'RANGE_ADD',
         parentName: 'media',
         parentID: this.props.media.id,
         connectionName: 'tags',
         edgeName: 'tagEdge',
         rangeBehaviors: {
           '': 'append'
         }
       }];
     }
   }

Mutation to be called

Expected return

Input parameters

How to update local cache

// import React, { Component, PropTypes } from 'react';
// import Relay from 'react-relay';
// import DeleteTagMutation from './DeleteTagMutation';
// 
// class Tag extends Component {
//   handleDelete() {
//     const id = this.props.tag.id;
       Relay.Store.commitUpdate(
         new DeleteTagMutation({
           id: id
         })
       );
//   }
// 
//   render() {
//     const tag = this.props.tag;
// 
//     return (
//       <div className="tag">
//         <span>{tag.tag}</span>
//         <span onClick={this.delete.bind(this)}>
//           x
//         </span>
//       </div>
//     );
//   }
// }
// 
// export default Tag;

Calling
a
mutation

One code, different platforms

• Yeoman Generator
• Generates a skeleton of a React / React Native app
• Can receive a URL as parameter
• Theming using SASS
• Documentation
• Platform abstraction
• Docker
• GraphQL / Relay

$ git clone 'https://github.com
  /meedan/generator-keefer.git'
$ cd generator-keefer
$ cp config.yml.example config.yml
$ npm install -g yo
$ npm link
$ yo keefer

$ PLATFORM=web npm run build

Web Application

$ PLATFORM=chrome npm run build

Chrome Extension

$ PLATFORM=android npm run build

Android App

github.com/meedan/react-native-share-menu

Use case: Same codebase, different platforms
(Android, iOS, Chrome extension, Firefox extension)

github.com/meedan/check-mark

Thanks! :)

slides.com/caiosba/rubyfuza18

http://ca.ios.ba

@caiosba