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第 11 屆 iThome 鐵人賽
DAY 4
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Modern Web

Framework Surfing 30天系列 第 4 篇

Day 4 - API server (Go, GraphQL) - part4

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前言

昨天發完文之後，一直覺得怪怪的，於是今天就去翻了 graphql.go 還有 gqlgen 產生出來的 exec.go，發現有一些地方要修改，抱歉啦。

今天的目錄會長這樣（修改的地方有標注）

  • build
  • cmd
    • gql-server
      • main.go
  • internal
    • gql：這裡有修改
      • generated
        • exec.go
      • models
        • generated.go
      • resolvers
        • generated
          • generated.go
        • main.go
        • post.go
        • user.go
      • schemas
        • schema.graphql：這裡有修改
    • handlers
      • gql.go：這裡有修改
      • heartbeat.go
    • orm
      • migration
        • jobs
          • seed_users.go
        • main.go
      • models
        • base.go
        • post.go
        • user.go
      • main.go
  • pkg
    • server
      • main.go
  • scripts
    • build.sh
    • gqlgen.sh：這裡有修改
    • run.sh
  • .env
  • .env.example
  • .gitignore
  • go.mod
  • go.sum
  • gqlgen.yml：這裡有修改

第一步 - 修改 schema.graphql

$ vim internal/gql/schema/schema.graphql

scalar Time
# Types
type User {
  id: ID!
  email: String!
  userId: String
  name: String
  firstName: String
  lastName: String
  nickName: String
  description: String
  location: String
  createdAt: Time!
  updatedAt: Time
  posts: [Post!]!
}

type Post {
  id: ID!
  title: String!
  content: String
  createdAt: Time!
  updatedAt: Time
  user: User
}

# Input Types
input UserInput {
  email: String
  userId: String
  displayName: String
  name: String
  firstName: String
  lastName: String
  nickName: String
  description: String
  location: String
}

input PostInput {
  title: String
  content: String
  userId: String
}

# Define mutations here
type Mutation {
  createUser(input: UserInput!): User!
  updateUser(id: ID!, input: UserInput!): User!
  deleteUser(id: ID!): Boolean!
  createPost(input: PostInput!): Post!
  updatePost(id: ID!, input: PostInput!): Post!
  deletePost(id: ID!): Boolean!
}

# Define queries here
type Query {
  users: [User!]!
  posts: [Post!]!
  user(id: ID!): User
  post(id: ID!): Post
}

第二步 - 修改 gqlgen.yml

修改這個是因為可以直接使用 orm 定義好的 models 來喂給 gelgen，這樣就不需要再將 orm 的 model 轉換成 gqlgen 的 model，而且生成的 exec.go 以及 resolvers.go 跟著改變，會幫我們將所有需要實作的 resolvers 都列出來，昨天的並沒有幫我們列出 User & Post 間需要的 resolvers。

$ vim gqlgem.yml

schema:
  - internal/gql/schemas/schema.graphql
# Let gqlgen know where to put the generated server
exec:
  filename: internal/gql/generated/exec.go # 這邊路徑有改
  package: generated
# Let gqlgen know where to put the generated models (if any)
model:
  filename: internal/gql/models/generated.go
  package: gqlmodels # 這邊 package name 有改
# Let gqlgen know where to put the generated resolvers
resolver:
  filename: internal/gql/resolvers/generated/generated.go
  type: Resolver
  package: resolvers
autobind: []
# 加上 models，並且指定到 orm 的 models
models:
  User:
    model: github.com/wtlin1228/go-gql-server/internal/orm/models.User
  Post:
    model: github.com/wtlin1228/go-gql-server/internal/orm/models.Post

修改後執行 $ scripts/gqlgen.sh

執行完 gqlgen 之後會發現自動產生的三個檔案都有變化

  1. gqlgen 的 model 裡面只剩下 PostInput 以及 UserInput
  2. gqlgen 的 exec.go 直接使用 orm 的 models
  3. resolvers 多了 postResolver 以及 userResolver

第二步 - 修改 Resolvers

一樣將 gqlgen 產生的 resolvers 檔案拆成三塊

  1. $ vim internal/gql/resolvers/main.go

    這裡跟昨天一樣幾乎沒變

     package resolvers

 import (
 	"github.com/wtlin1228/go-gql-server/internal/gql/generated"
 	"github.com/wtlin1228/go-gql-server/internal/orm"
 )

 type Resolver struct {
 	ORM *orm.ORM
 }

 func (r *Resolver) Mutation() generated.MutationResolver {
 	return &mutationResolver{r}
 }
 func (r *Resolver) Post() generated.PostResolver {
 	return &postResolver{r}
 }
 func (r *Resolver) Query() generated.QueryResolver {
 	return &queryResolver{r}
 }
 func (r *Resolver) User() generated.UserResolver {
 	return &userResolver{r}
 }

 type mutationResolver struct{ *Resolver }

 type queryResolver struct{ *Resolver }

  2. $ vim internal/gql/resolvers/post.go

    寫法跟昨天很像，只是精簡了很多，然後多了一些 resolvers

     package resolvers

 import (
 	"context"

 	"github.com/gofrs/uuid"
 	gqlmodels "github.com/wtlin1228/go-gql-server/internal/gql/models"
 	"github.com/wtlin1228/go-gql-server/internal/orm/models"
 )

 // Mutations
 func (r *mutationResolver) CreatePost(ctx context.Context, input gqlmodels.PostInput) (*models.Post, error) {
 	return postCreateUpdate(r, input, false)
 }
 func (r *mutationResolver) UpdatePost(ctx context.Context, id string, input gqlmodels.PostInput) (*models.Post, error) {
 	return postCreateUpdate(r, input, true, id)
 }
 func (r *mutationResolver) DeletePost(ctx context.Context, id string) (bool, error) {
 	return postDelete(r, id)
 }

 // Queries
 func (r *queryResolver) Posts(ctx context.Context) ([]*models.Post, error) {
 	var posts []*models.Post
 	r.ORM.DB.Find(&posts)
 	return posts, nil
 }

 func (r *queryResolver) Post(ctx context.Context, id string) (*models.Post, error) {
 	post := &models.Post{}
 	r.ORM.DB.First(&post)
 	return post, nil
 }

 type postResolver struct{ *Resolver }

 func (r *postResolver) ID(ctx context.Context, obj *models.Post) (string, error) {
 	return obj.ID.String(), nil
 }
 func (r *postResolver) User(ctx context.Context, obj *models.Post) (*models.User, error) {
 	return r.Query().User(ctx, obj.UserID.String())
 }

 // Mutation Helper functions
 func postCreateUpdate(r *mutationResolver, input gqlmodels.PostInput, update bool, ids ...string) (*models.Post, error) {
 	dbo, err := GQLInputPostToDBPost(&input, update, ids...)
 	if err != nil {
 		return nil, err
 	}
 	// Create scoped clean db interface
 	db := r.ORM.DB.New().Begin()
 	if !update {
 		db = db.Create(dbo).First(dbo) // Create the post
 	} else {
 		db = db.Model(&dbo).Update(dbo).First(dbo) // Or update it
 	}
 	if db.Error != nil {
 		db.RollbackUnlessCommitted()
 		return nil, db.Error
 	}
 	db = db.Commit()
 	return dbo, nil
 }

 func postDelete(r *mutationResolver, id string) (bool, error) {
 	whereID := "id = ?"
 	// Convert id from type string to type uuid.UUID
 	convertedID, err := uuid.FromString(id)
 	if err != nil {
 		return false, err
 	}
 	// Create scoped clean db interface
 	db := r.ORM.DB.New().Begin()
 	// Find the post
 	dbPost := &models.Post{}
 	err = db.Where(whereID, convertedID).First(dbPost).Error
 	if err != nil {
 		return false, err
 	}
 	// Delete the post
 	if err := db.Delete(dbPost).Error; err != nil {
 		db.RollbackUnlessCommitted()
 		return false, err
 	}
 	db = db.Commit()
 	return true, nil
 }

 // GQLInputPostToDBPost transforms [post] gql input to db model
 func GQLInputPostToDBPost(i *gqlmodels.PostInput, update bool, ids ...string) (o *models.Post, err error) {
 	o = &models.Post{
 		Title:   *i.Title,
 		Content: i.Content,
 	}
 	// convert the id from type String to type uuid.UUID
 	if len(ids) > 0 {
 		updID, err := uuid.FromString(ids[0])
 		if err != nil {
 			return nil, err
 		}
 		o.ID = updID
 	}
 	return o, err
 }

  3. $ vim internal/gql/resolvers/user.go

    寫法跟昨天很像，只是精簡了很多，然後多了一些 resolvers

     package resolvers

 import (
 	"context"
 	"errors"

 	"github.com/gofrs/uuid"
 	gqlmodels "github.com/wtlin1228/go-gql-server/internal/gql/models"
 	"github.com/wtlin1228/go-gql-server/internal/orm/models"
 )

 // Mutations
 func (r *mutationResolver) CreateUser(ctx context.Context, input gqlmodels.UserInput) (*models.User, error) {
 	return userCreateUpdate(r, input, false)
 }
 func (r *mutationResolver) UpdateUser(ctx context.Context, id string, input gqlmodels.UserInput) (*models.User, error) {
 	return userCreateUpdate(r, input, true, id)
 }
 func (r *mutationResolver) DeleteUser(ctx context.Context, id string) (bool, error) {
 	return userDelete(r, id)
 }

 // Queries
 func (r *queryResolver) Users(ctx context.Context) ([]*models.User, error) {
 	var users []*models.User
 	r.ORM.DB.Preload("Posts").Find(&users)
 	return users, nil
 }

 func (r *queryResolver) User(ctx context.Context, id string) (*models.User, error) {
 	user := &models.User{}
 	r.ORM.DB.Preload("Posts").First(&user)
 	return user, nil
 }

 type userResolver struct{ *Resolver }

 func (r *userResolver) ID(ctx context.Context, obj *models.User) (string, error) {
 	return obj.ID.String(), nil
 }

 // Mutation Helper functions
 func userCreateUpdate(r *mutationResolver, input gqlmodels.UserInput, update bool, ids ...string) (*models.User, error) {
 	dbo, err := GQLInputUserToDBUser(&input, update, ids...)
 	if err != nil {
 		return nil, err
 	}
 	// Create scoped clean db interface
 	db := r.ORM.DB.New().Begin()
 	if !update {
 		db = db.Create(dbo).First(dbo) // Create the user
 	} else {
 		db = db.Model(&dbo).Update(dbo).First(dbo) // Or update it
 	}
 	if db.Error != nil {
 		db.RollbackUnlessCommitted()
 		return nil, db.Error
 	}
 	db = db.Commit()
 	return dbo, nil
 }

 func userDelete(r *mutationResolver, id string) (bool, error) {
 	whereID := "id = ?"
 	// Convert id to uuid.UUID from string
 	convertedID, err := uuid.FromString(id)
 	if err != nil {
 		return false, err
 	}
 	// Create scoped clean db interface
 	db := r.ORM.DB.New().Begin()
 	// Find the user
 	dbUser := &models.User{}
 	err = db.Where(whereID, convertedID).First(dbUser).Error
 	if err != nil {
 		return false, err
 	}
 	// Find the user's posts
 	dbPosts := []*models.Post{}
 	db.Model(&dbUser).Related(&dbPosts, "Posts")
 	// Delete posts
 	for _, dbPost := range dbPosts {
 		if err := db.Delete(dbPost).Error; err != nil {
 			db.RollbackUnlessCommitted()
 			return false, err
 		}
 	}
 	// Delete the user
 	if err := db.Delete(dbUser).Error; err != nil {
 		db.RollbackUnlessCommitted()
 		return false, err
 	}
 	db = db.Commit()
 	return true, nil
 }

 // GQLInputUserToDBUser transforms [user] gql input to db model
 func GQLInputUserToDBUser(i *gqlmodels.UserInput, update bool, ids ...string) (o *models.User, err error) {
 	o = &models.User{
 		UserID:      i.UserID,
 		Name:        i.Name,
 		FirstName:   i.FirstName,
 		LastName:    i.LastName,
 		NickName:    i.NickName,
 		Description: i.Description,
 		Location:    i.Location,
 	}
 	if i.Email == nil && !update {
 		return nil, errors.New("Field [email] is required")
 	}
 	if i.Email != nil {
 		o.Email = *i.Email
 	}
 	if len(ids) > 0 {
 		updID, err := uuid.FromString(ids[0])
 		if err != nil {
 			return nil, err
 		}
 		o.ID = updID
 	}
 	return o, err
 }

第三步 - 修改 handler/gql.go

package handlers

import (
	"github.com/99designs/gqlgen/handler"
	"github.com/gin-gonic/gin"
  // 改這邊
	gql "github.com/wtlin1228/go-gql-server/internal/gql/generated"
	"github.com/wtlin1228/go-gql-server/internal/gql/resolvers"
	"github.com/wtlin1228/go-gql-server/internal/orm"
)

// GraphqlHandler defines the GQLGen GraphQL server handler
func GraphqlHandler(orm *orm.ORM) gin.HandlerFunc {
	// NewExecutableSchema and Config are in the generated.go file
	c := gql.Config{
		Resolvers: &resolvers.Resolver{
			ORM: orm, // pass in the ORM instance in the resolvers to be used
		},
	}

	h := handler.GraphQL(gql.NewExecutableSchema(c))

	return func(c *gin.Context) {
		h.ServeHTTP(c.Writer, c.Request)
	}
}

// PlaygroundHandler Defines the Playground handler to expose our playground
func PlaygroundHandler(path string) gin.HandlerFunc {
	h := handler.Playground("Go GraphQL Server", path)
	return func(c *gin.Context) {
		h.ServeHTTP(c.Writer, c.Request)
	}
}

完成

$ scripts/run.sh

測試一下，沒有問題！

程式碼放在這邊 Here

推薦文章

https://gqlgen.com/getting-started/

https://stackedco.de/building-a-recipe-crud-api-with-golang-graphql-and-mysql

https://blog.csdn.net/liuyh73/article/details/85028977


上一篇
Day 3 - API server (Go, GraphQL) - part3
下一篇
Day 5 - 設計前端頁面 - part 1
系列文
Framework Surfing 30天 共 6 篇
  1. 2
    Day 2 - API server (Go, GraphQL) - part2
  2. 3
    Day 3 - API server (Go, GraphQL) - part3
  3. 4
    Day 4 - API server (Go, GraphQL) - part4
  4. 5
    Day 5 - 設計前端頁面 - part 1
  5. 6
    Day 6 - React with Apollo - part 1
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