ent 基本使用 二 简单create && query

接上文，前边我们了解了关于基本代码生成以及schema 迁移的学习，下边我们看看基本的数据操作
参考代码： https://github.com/rongfengliang/ent-demo

环境准备

• mysql 数据库

  使用docker-compose 运行

 

version: "3"

services:

  mysql:

    image: mysql:5.7.16

    ports:

      - 3306:3306

    command: --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci

    environment:

      MYSQL_ROOT_PASSWORD: dalongrong

      MYSQL_DATABASE: gogs

      MYSQL_USER: gogs

      MYSQL_PASSWORD: dalongrong

      TZ: Asia/Shanghai

• go mod 项目

go mod github.com/rongfengliang/ent-demo

• 项目约定
  为了方便测试，使用多main 入口，同时使用makefile 进行管理
  项目结构

 

├── Makefile

├── README.md

├── build

│ ├── create

│ ├── migration

│ └── query

├── cmd

│ ├── create

│ │ └── main.go

│ ├── migration

│ │ └── main.go

│ └── query

│ └── main.go

├── docker-compose.yaml

├── ent

│ ├── client.go

│ ├── config.go

│ ├── context.go

│ ├── ent.go

│ ├── example_test.go

│ ├── migrate

│ │ ├── migrate.go

│ │ └── schema.go

│ ├── predicate

│ │ └── predicate.go

│ ├── schema

│ │ └── user.go

│ ├── tx.go

│ ├── user

│ │ ├── user.go

│ │ └── where.go

│ ├── user.go

│ ├── user_create.go

│ ├── user_delete.go

│ ├── user_query.go

│ └── user_update.go

├── go.mod

└── go.sum

说明
cmd 目录为操作，ent 为代码生成
Makefile

 

.PHONY : clean

all: clean cli

clean: 

 rm -rf build/*

cli:

 go build -o build ./cmd/...

常见数据处理

• schmma 处理
  这个不是必须，如果项目已经运行过 ，可以不用运行 ，首次运行的话需要添加

 

go run cmd/migration/main.go 

• 添加数据操作
  cmd/create/main.go

 

package main

​

import (

 "context"

 "fmt"

 "log"

​

 _ "github.com/go-sql-driver/mysql"

 "github.com/rongfengliang/ent-demo/ent"

)

​

func main() {

 client, err := ent.Open("mysql", "root:dalongrong@tcp(127.0.0.1)/gogs")

 if err != nil {

  log.Fatalf("failed opening connection to sqlite: %v", err)

 }

 defer client.Close()

 ctx := context.Background()

 createUser(ctx, client)

​

}

​

func createUser(ctx context.Context, client *ent.Client) (*ent.User, error) {

 u, err := client.User.

  Create().

  SetAge(30).

  SetName("a8m").

  Save(ctx)

 if err != nil {

  return nil, fmt.Errorf("failed creating user: %v", err)

 }

 log.Println("user was created: ", u)

 return u, nil

}

说明：
从上边可以看出，使用很简单

• 运行效果

 

go run cmd/create/main.go

​

2019/10/14 13:53:20 user was created: User(id=5, age=30, name=a8m)

➜ first git:(master) ✗ 

数据查询处理

• 查询代码
  cmd/query/main.go

 

package main

​

import (

 "context"

 "fmt"

 "log"

​

 _ "github.com/go-sql-driver/mysql"

 "github.com/rongfengliang/ent-demo/ent"

 "github.com/rongfengliang/ent-demo/ent/user"

)

​

func main() {

​

 client, err := ent.Open("mysql", "root:dalongrong@tcp(127.0.0.1)/gogs")

 if err != nil {

  log.Fatalf("failed opening connection to sqlite: %v", err)

 }

 defer client.Close()

 ctx := context.Background()

 queryUser(ctx, client)

}

​

func queryUser(ctx context.Context, client *ent.Client) (*ent.User, error) {

 u, err := client.User.

  Query().

  Where(user.ID(1)).

  // `Only` fails if no user found,

  // or more than 1 user returned.

  Only(ctx)

 if err != nil {

  return nil, fmt.Errorf("failed querying user: %v", err)

 }

 log.Println("user returned: ", u)

 return u, nil

}

• 运行效果

go run cmd/query/main.go

2019/10/14 13:54:49 user returned: User(id=1, age=30, name=a8m)

说明

以上是一个简单的insert 以及查询处理，后边会介绍下关于图查询的处理,实际上ent 还包含了数据校验的处理

参考资料

https://entgo.io/docs/getting-started/
https://github.com/rongfengliang/ent-demo