1. Why we moving API from REST to Graphql? 2. What is Graphql? 3. Graphql in Golang (Why we choose Golang) 4. How to testing Graphql in Golang 5. Deploy Graphql application

1. GRAPHQL IN GO
MODERNWEB 2018

2. ABOUT ME
Open source contributor
1. Gitea
2. Drone
3. Gin
appleboy @ GitHub
appleboy @ twitter
appleboy @ slideshare
appleboy46 @ facebook
2

3. AGENDA
▸ Why we moving API from REST to Graphql?
▸ What is Graphql?
▸ Graphql in Golang (Why we choose Golang)
▸ How to testing Graphql in Golang
▸ Deploy Graphql application

4. MOVING REST TO GRAPHQL
icon from https://bit.ly/2LhOpZA

5. 1. LARGE REQUEST IN SINGLE PAGE
https://bit.ly/2NpS4Fu

6. 1. LARGE REQUEST IN SINGLE PAGE

7. CUSTOM FIELDS
/api/scene/1?field=name,description,created_at

8. CUSTOMENDPOINT
/api/scene/1/mobile?field=name,description
/api/scene/1/web?field=name,description

9. DOCUMENTATION?
HOW TO GENERATE DOCUMENT AUTOMATICALLY?
API DOC
Swagger

10. UPDATE API
GENERATE DOC
BACKEND
FRONTEND MOBILETESTING

11. /**
* @api {get} /scene/:id Request Scene information
* @apiName GetScene
* @apiGroup Scene
*
* @apiParam {Number} id Scenes unique ID.
*
* @apiSuccess {String} title Title of the Scene.
* @apiSuccess {String} desc Description of the Scene.
*/

12. GRAPHQL

13. WHATISGRAPHQL?
IT IS A QUERY LANGUAGE

14. {
myScene {
name
description
}
}
LEXED
PARSED
VALIDATED
EXECUTED

15. {
scene(id: 1) {
name
description
}
}
LEXED
PARSED
VALIDATED
EXECUTED

16. {
scene(id: 1) {
name
description
items(type: DEVICE) {
id
name
url
}
}
}
Graphql Request

17. {
"scene": {
"name": "foo",
"description": “bar",
"items": [{
"id": 1,
"name": "test_1",
"url": "http://foo.com"
}, {
"id": 2,
"name": "test_2",
"url": "http://bar.com"
}]
}
}
JSON Response

18. /api/scene/1
/api/scene/1/item
/api/scene/1/all

19. TYPE SYSTEM
GRAPHQL LANGUAGE

20. {
myScene {
name
description
}
}

21. {
scene(id: 1) {
name
description
items(type: DEVICE) {
id
name
url
}
}
}

22. type QueryRoot {
myScene: Scene
scene(id: ID!): Scene
}

23. {
scene(id: 1) {
name
description
items(type: DEVICE) {
id
name
url
}
}
}
Graphql Request

24. type Scene {
name: String!
description: String
items(type: ItemEnum): [Item]
}
enum ItemEnum {
DEVICE,
TEST_DEVICE,
URL
}

25. {
scene(id: 1) {
name
description
items(type: DEVICE) {
id
name
url
}
}
}
Graphql Request

26. type Item {
id: ID!
name: String!
url: String
}

27. INTROSPECTION
GRAPHQL LANGUAGE

28. {
__schema {
queryType {
name
}
}
}

29. {
"data": {
"__schema": {
"queryType": {
"name": "Query"
}
}
}
}

30. WHY NEED THE INTROSPECTION
▸code generation
▸auto documentation
▸static validation
▸IDE Integration

31. https://github.com/prismagraphql/graphql-playground

32. https://www.prisma.io/blog/introducing-graphql-playground-f1e0a018f05d/

33. RESOLVINGFIELDS
GRAPHQL LANGUAGE

34. type Item {
id: ID
type: sceneEnum
name: String
}

35. "id": &graphql.Field{
Type: graphql.Int,
},
INT FLOAT STRING BOOLEAN ID

36. type Item {
id: ID
type: sceneEnum
name: String
}

37. "TEST_DEVICE": &graphql.EnumValueConfig{
Value: int(model.TypeTestDevice),
Description: "test device.",
},
"DEVICE": &graphql.EnumValueConfig{
Value: int(model.TypeDevice),
Description: "device.",
},
"URL": &graphql.EnumValueConfig{
Value: int(model.TypeURL),
Description: "url.",
},

38. "name": &graphql.Field{
Type: graphql.String,
Resolve: func(p graphql.ResolveParams) (interface{}, error) {
o, _ := p.Source.(*model.Scene)
return "Hello, " + o.Name, nil
},
},
Return Custom Value

39. MUTATION
GRAPHQL LANGUAGE

40. mutation {
createScene(
title: "foo",
description: "bar"
) {
id
title
description
url
}
}

41. // Schema is the GraphQL schema served by the server.
var Schema, _ = graphql.NewSchema(graphql.SchemaConfig{
Query: rootQuery,
Mutation: rootMutation,
Types: types,
})
Query and Mutation

42. SINGLE ENDPOINT
POST /graphql

43. GRAPHQL IN GOLANG
WHY WE CHOOSE GOLANG?

44. WHY WE CHOOSE GOLANG?
▸Compiles Into Single Binary
▸Static Type System
▸Performance
▸Easy to Deploy
▸Learning Curve

45. BENCHMARKOFGRAPHQLFRAMEWORKINGOLANG
▸graphql-go/graphql
▸playlyfe/go-graphql
▸graph-gophers/graphql-go
▸samsarahq/thunder

46. https://github.com/appleboy/golang-graphql-benchmark
$ go test -v -bench=. -benchmem

47. VEKTAH/GQLGEN
GO GENERATE BASED GRAPHQL SERVER
LIBRARY
https://github.com/vektah/gqlgenhttps://youtu.be/3dpqYMqyiOg

49. API SERVER
API SERVER
GRAPHQLSERVER
GRAPHQL GATEWAY

50. GRAPHQLINGOLANG
PACKAGE IN GOLANG

51. FRAMEWORKINGO

52. func Handler() gin.HandlerFunc {
h := handler.New(&handler.Config{
Schema: &schema.Schema,
Pretty: true,
})
return func(c *gin.Context) {
h.ServeHTTP(c.Writer, c.Request)
}
}
graphql schema

53. JWT TOKEN
SERVER
GRAPHQL
SERVER

54. func Check() gin.HandlerFunc {
return func(c *gin.Context) {
token := c.GetHeader("Authorization")
user, err := authUser(token)
if token != "" && err != nil {
logrus.Errorf("authUser error: %s", err.Error())
}
if user != nil && user.Email != "" {
c.Set("email", user.Email)
c.Set("user_id", user.UserID)
}
ctx := context.WithValue(
c.Request.Context(),
config.ContextKeyUser,
user,
)
c.Request = c.Request.WithContext(ctx)
}
}
store user data

55. var Schema, _ = graphql.NewSchema(graphql.SchemaConfig{
Query: rootQuery,
Mutation: rootMutation,
})
var rootMutation = graphql.NewObject(
graphql.ObjectConfig{
Name: "RootMutation",
Description: "Root Mutation",
Fields: graphql.Fields{
"updateUser": &updateUser,
"createScene": &createScene,
"updateScene": &updateScene,
"deleteScene": &deleteScene,
},
})
var rootQuery = graphql.NewObject(
graphql.ObjectConfig{
Name: "RootQuery",
Description: "Root Query",
Fields: graphql.Fields{
"queryUser": &queryUser,
"searchUser": &searchUser,
"queryScene": &queryScene,
},
})
query
mutation

56. GRAPHQL ERROR
BETTER ERROR HANDLING

57. {
"data": {
"post": null
},
"errors": [
{
"message": "Internal Error: 404 not found",
"locations": [
{
"line": 2,
"column": 3
}
],
"path": [
"post"
]
}
]
}
single message
error location

58. func (g FormattedError) MarshalJSON() ([]byte, error)
{
m := map[string]interface{}{}
for k, v := range g.Extensions {
m[k] = v
}
m["message"] = g.Message
m["locations"] = g.Locations
return json.Marshal(m)
}
Marshal JSON
custom key value

59. func FormatError(err error, arg ...interface{}) gqlerrors.FormattedError
{
switch err := err.(type) {
case gqlerrors.FormattedError:
return err
case *Error:
return gqlerrors.FormattedError{
Message: fmt.Sprintf(err.Error(), arg...),
Extensions: gqlerrors.ErrorExtensions{
"code": err.Type.Code(),
"type": err.Type,
},
}
} custom error
original error

60. GRAPHQL N+1
DATA LOADER

61. 1. LARGE REQUEST IN SINGLE PAGE

62. {
myScene(id: 1) {
name
description
role {
id
user {
email
}
model
}
}
}

63. ORM IN GOLANG
GOORM VS XORM

64. type Scene struct {
ID int64 `xorm:"pk autoincr" json:"id"`
Image string `json:"image,omitempty"`
CreatedAt time.Time `json:"createdAt,omitempty"`
UpdatedAt time.Time `json:"updatedAt,omitempty"`
DeletedAt time.Time `xorm:"deleted"`
// reference
Items []*SceneItem `xorm:"-" json:"items,omitempty"`
User *User `xorm:"-" json:"user,omitempty"`
Role *SceneAccess `xorm:"-" json:"role,omitempty"`
}
Data Model
user role permission

65. "user": &graphql.Field{
Type: userType,
Resolve: func(p graphql.ResolveParams) (interface{}, error) {
o, ok := p.Source.(*model.Shorten)
if !ok {
return nil, errMissingSource
}
if o.User != nil {
return o.User, nil
}
return getUserFromLoader(p.Context, o.UserID)
},
},
exist in model?
fetch from loader

66. GET DATA FROM DATABASE IF NOT EXIST
func userBatch(ctx context.Context, keys dataloader.Keys) []*dataloader.Result {
var results []*dataloader.Result
id, _ := helper.GetCacheID(keys[0].String())
user, err := model.GetUserByID(id.(int64))
results = append(results, &dataloader.Result{
Data: user,
Error: err,
})
return results
}
fetch from DB

67. GRAPHQLDATALOADER
ONLY SUPPORT MEMORY, LRU OR TTL
CACHE

68. INTEGRATE WITH REDIS SERVICE
GRAPHQLDATALOADER

69. func batchFunc(_ context.Context, keys dataloader.Keys) []*dataloader.Result
{
results := make([]*dataloader.Result, len(keys))
// get what you can from redis
values, _ := redisClient.MGet(...keys.Keys()).Result()
// make a list of everything that was not found in redis
var cacheMisses map[int]string
for i := range keys {
if values[i] == redis.Nil {
cacheMisses[i] = keys[i].String()
} else {
results[i] = &dataloader.Result{values[i], nil}
}
}
// get the missing items from more expensive location (like DB)
for idx, key := range cacheMisses {
value, err := db.GetValues(key) // Pseudo code!
redisClient.Set(key, value)
results[idx] = &dataloader.Result{value, err}
}
return results
}
miss from redis
fetch from DB

70. HOW TO TEST GRAPHQL SCHEMA?
GRAPHQL TESTING

71. https://code.likeagirl.io/the-7-steps-to-a-complete-code-review-abdfd39e75f1

72. RAILS-LIKE TEST FIXTURES FOR GO
GO TEST FIXTURES
https://github.com/go-testfixtures/testfixtures

73. -
id: 1
email: foo@gmail.com
full_name: foo
avatar: http://foo.com
avatar_email: foo@gmail.com
-
id: 2
email: bar@gmail.com
full_name: bar
avatar: http://bar.com
avatar_email: bar@gmail.com
real data in DB

74. test := T{
Query: `
query QueryShortenURL (
$slug: String!
) {
QueryShortenURL(slug: $slug) {
url
}
}
`,
Schema: Schema,
Expected: &graphql.Result{
Data: map[string]interface{}{
"QueryShortenURL": map[string]interface{}{
"url": "http://example.com",
},
},
},
}
graphql query
expect data

75. params := graphql.Params{
Schema: test.Schema,
RequestString: test.Query,
Context: ctx,
VariableValues: map[string]interface{}{
"slug": "abcdef",
},
}
testGraphql(test, params, t)
ctx := newContextWithUser(context.TODO(), user)
user data in context
graphql variable

76. all pass
testing in sqlite

77. GRAPHQLDEPLOYMENT
HOW TO DEPLOY GOLANG APP?

78. GO-GGZ/GGZ
AN URL SHORTENER SERVICE WRITTEN IN GO
https://github.com/go-ggz/ggz

79. Thanks