Go语言ORM框架 gorm 的使用方法详解

GORM框架的使用方法

概述

package main

import (

"https://www.360docs.net/doc/3c9174631.html,/jinzhu/gorm"

_ "https://www.360docs.net/doc/3c9174631.html,/jinzhu/gorm/dialects/mysql"

)

type Product struct {

ID uint`gorm:"primary_key"`

Code string

Price uint

}

func main() {

db,err := gorm.Open("mysql",

"user:password@/dbname?charset=utf8&parseTime=True&loc=Local") if err != nil {

panic("failed to connect database")

}

defer db.Close()

// 自动迁移表，生成的表名为 products

db.AutoMigrate(&Product{})

// Create

db.Create(&Product{Code: "L1212", Price: 1000})

// Read

var product Product

db.First(&product, 1) // find product with id 1

db.First(&product, "code = ?", "L1212") // find product with code l1212

// Update

db.Model(&product).Update("Price", 2000)

//Delete

db.Delete(&product)

}

模型定义

4 个特殊字段。其中ID 字段默认为主键字段，可以无需加Tag `gorm:"primary_key"`。

type Model struct {

IDuint `gorm:"primary_key"`

CreatedAttime.Time

UpdatedAttime.Time

DeletedAt *time.Time

}

使用 gorm.Model 自动生成这4个字段。效果等同上。

type User struct {

gorm.Model

}

修改表名

type Product struct {

ID uint

Code string

Price uint

}

//修改默认表名func (Product) TableName() string {

return"product2"

}

type Email struct {

ID int

Email string

}

func main() {

db, err := gorm.Open("mysql", "root:root@tcp(localhost:3306)/gorm")

if err != nil {

panic("failed to connect database")

}

defer db.Close()

//设置默认表名前缀

gorm.DefaultTableNameHandler = func(db *gorm.DB,

defaultTableName string) string {

return"prefix_" + defaultTableName

}

//自动生成表

db.AutoMigrate(&Product{}, &Email{})

}

设置字段

type Product struct {

ID uint`gorm:"primary_key:id"`

Num int`gorm:"AUTO_INCREMENT:number"`

Code string

Price uint`gorm:"default:'1000'"`

Tag []Tag `gorm:"many2many:tag;"`

Date time.Time `gorm:"-"`

}

type Email struct {

ID int`gorm:"primary_key:id"`

UserID int`gorm:"not null;index"`

Email string`gorm:"type:varchar(100);unique_index"`

Subscribed bool

}

type Tag struct {

Name string

}

func main() {

db, err := gorm.Open("mysql", "root:root@tcp(localhost:3306)/gorm")

if err != nil {

panic("failed to connect database")

}

defer db.Close()

gorm.DefaultTableNameHandler =

func(db *gorm.DB, defaultTableName string) string {

return"demo_" + defaultTableName

}

db.AutoMigrate(&Product{}, &Email{})

}

设置外键字段

type Profile struct {

gorm.Model

Referint

Namestring

}

type User struct {

gorm.Model

ProfileProfile`gorm:"ForeignKey:ProfileID;AssociationForeignKey:Refer"`

ProfileIDint

}

增删改查

增

type Animal struct {

ID int64

Name string`gorm:"default:'galeone'"`

Age int64

}

var animal = Animal{Age: 99, Name: ""}

db.Create(&animal)

查

// SELECT * FROMusersORDERBYidLIMIT1;

db.First(&user)

// SELECT * FROMusersORDERBYidDESCLIMIT1;

https://www.360docs.net/doc/3c9174631.html,st(&user)

// SELECT * FROMusers;

db.Find(&users)

// SELECT * FROMusersWHEREid = 10;

db.First(&user, 10)

添加 where子句

// Get first matched record

db.Where("name = ?", "jinzhu").First(&user)

//// SELECT * FROM users WHERE name = 'jinzhu' limit 1;

// Get all matched records db.Where("name = ?", "jinzhu").Find(&users)

//// SELECT * FROM users WHERE name = 'jinzhu';

db.Where("name <> ?", "jinzhu").Find(&users)

// IN db.Where("name in (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users)

// LIKE db.Where("name LIKE ?", "%jin%").Find(&users)

// AND db.Where("name = ? AND age >= ?", "jinzhu", "22").Find(&users)

// Time db.Where("updated_at > ?", lastWeek).Find(&users)

db.Where("created_at BETWEEN ? AND ?", lastWeek, today).Find(&users)

结构或者 map

// Struct

db.Where(&User{Name:"jinzhu", Age:20}).First(&user)

//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20 LIMIT 1;

// Map

db.Where(map[string]interface{}{"name": "jinzhu", "age": 20}).Find(&users)

//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20;

// Slice of primary keys

db.Where([]int64{20, 21, 22}).Find(&users)

//// SELECT * FROM users WHERE id IN (20, 21, 22);

inline condition

// Get by primary key (only works for integer primary key)

db.First(&user, 23)//// SELECT * FROM users WHERE id = 23 LIMIT 1;

// Get by primary key if it were a non-integer type

db.First(&user, "id = ?", "string_primary_key")

//// SELECT * FROM users WHERE id = 'string_primary_key' LIMIT 1;

// Plain SQL db.Find(&user, "name = ?", "jinzhu")

//// SELECT * FROM users WHERE name = "jinzhu";

db.Find(&users, "name <> ? AND age > ?", "jinzhu", 20)

//// SELECT * FROM users WHERE name <>"jinzhu" AND age > 20;

// Struct db.Find(&users, User{Age: 20})//// SELECT * FROM users WHERE age = 20; // Map db.Find(&users, map[string]interface{}{"age": 20})

//// SELECT * FROM users WHERE age = 20;

Select 选择

db.Select("name, age").Find(&users)//// SELECT name, age FROM users;

db.Select([]string{"name", "age"}).Find(&users)//// SELECT name, age FROM users;

db.Table("users").Select("COALESCE(age,?)", 42).Rows()

//// SELECT COALESCE(age,'42') FROM users;

排序

db.Order("age desc, name").Find(&users)//// SELECT * FROMusersORDERBY age desc, name; // Multiple orders

db.Order("age desc").Order("name").Find(&users)

//// SELECT * FROMusersORDERBY age desc, name;

// ReOrder

db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)

//// SELECT * FROMusersORDERBY age desc; (users1)

//// SELECT * FROMusersORDERBY age; (users2)

limit 子句

db.Limit(3).Find(&users)//// SELECT * FROMusersLIMIT3;

// Cancel limit condition with -1

db.Limit(10).Find(&users1).Limit(-1).Find(&users2)

//// SELECT * FROMusersLIMIT10; (users1)//// SELECT * FROMusers; (users2)

count

db.Model(&User{}).Where("name = ?", "jinzhu").Count(&count)

//// SELECT count(*) FROM users WHERE name = 'jinzhu'; (count)

db.Table("deleted_users").Count(&count)//// SELECT count(*) FROM deleted_users; group & having

typeResultstruct {

Date time.Time

Totalint64

}

db.Table("orders").Select("date(created_at) as date,

sum(amount) as total").Group("date(created_at)")

.Having("sum(amount) > ?", 100).Scan(&results)

Joins

db.Table("users").Select("https://www.360docs.net/doc/3c9174631.html,, emails.email")

.Joins("left join emails on https://www.360docs.net/doc/3c9174631.html,er_id = users.id").Scan(&results) Scan

typeResultstruct {

Name string

Age int

}

var result Result

db.Table("users").Select("name, age").Where("name = ?", 3).Scan(&result)

// Raw SQL db.Raw("SELECT name, age FROM users WHERE name = ?", 3).Scan(&result) 指定表名

// Create`deleted_users`tablewithstructUser's definition

db.Table("deleted_users").CreateTable(&User{})

改

save 全部更新

db.First(&user)

https://www.360docs.net/doc/3c9174631.html, = "jinzhu 2"

user.Age = 100

db.Save(&user)

//// UPDATEusersSETname='jinzhu 2', age=100, birthday='2016-01-01',

updated_at = '2013-11-17 21:34:10'WHEREid=111;

部分更新

db.Model(&user).Update("name", "hello")db.Model(&user)

.Updates(User{Name: "hello", Age: 18})

对更新语句进行 select 和 omit

db.Model(&user).Select("name").Updates(map[string]interface{}

{"name": "hello", "age": 18, "actived": false})

//// UPDATE users SET name='hello', updated_at='2013-11-17 21:34:10' WHERE id=111;

db.Model(&user).Omit("name").Updates(map[string]interface{}

{"name": "hello", "age": 18, "actived": false})

//// UPDATE users SET age=18, actived=false, updated_at='2013-11-17 21:34:10' WHERE id=111;删

// Delete an existing record

db.Delete(&email)//// DELETEfrom emails whereid=10;

软删除

当设置DeletedAt 字段时，默认不会真的删除该记录。只会把该记录的DeletedAt 的值设置为当前时间。

// 执行软删除

db.Delete(&user)

//// UPDATEusersSET deleted_at="2013-10-29 10:23"WHEREid = 111;

// 虽然记录没有永久删除。但是查询时依然不会查询到该记录

db.Where("age = 20").Find(&user)

//// SELECT * FROMusersWHERE age = 20AND deleted_at IS NULL;

// 可以通过指定域查询到该软删除的记录

db.Unscoped().Where("age = 20").Find(&users)

//// SELECT * FROMusersWHERE age = 20;

// 通过指定域进行永久删除

db.Unscoped().Delete(&order)

//// DELETEFROM orders WHEREid=10;

子查询

db.Preload("Orders").Find(&users)//// SELECT * FROMusers;//// SELECT * FROM orders WHERE user_id IN (1,2,3,4);

db.Preload("Orders", "state NOT IN (?)", "cancelled").Find(&users)

//// SELECT * FROMusers;

//// SELECT * FROM orders WHERE user_id IN (1,2,3,4) AND state NOTIN ('cancelled'); db.Where("state = ?", "active")

.Preload("Orders", "state NOT IN (?)", "cancelled").Find(&users)

//// SELECT * FROMusersWHERE state = 'active';

//// SELECT * FROM orders WHERE user_id IN (1,2) AND state NOTIN ('cancelled');

db.Preload("Orders").Preload("Profile").Preload("Role").Find(&users)

//// SELECT * FROMusers;

//// SELECT * FROM orders WHERE user_id IN (1,2,3,4); // has many

//// SELECT * FROMprofilesWHERE user_id IN (1,2,3,4); // has one

//// SELECT * FROMrolesWHEREidIN (4,5,6); // belongs to

db.Preload("Orders.OrderItems").Find(&users)

db.Preload("Orders", "state = ?", "paid").Preload("Orders.OrderItems").Find(&users) 关联存储

增和改时默认级联处理

user := User{

Name: "jinzhu",

BillingAddress: Address{Address1: "Billing Address - Address 1"},

ShippingAddress: Address{Address1: "Shipping Address - Address 1"},

Emails: []Email{

{Email: "jinzhu@https://www.360docs.net/doc/3c9174631.html,"},

{Email: "jinzhu-2@example@https://www.360docs.net/doc/3c9174631.html,"},

},

Languages: []Language{

{Name: "ZH"},

{Name: "EN"},

},

}

db.Create(&user)//// BEGIN TRANSACTION;

//// INSERT INTO "addresses" (address1) VALUES ("Billing Address - Address 1"); //// INSERT INTO "addresses" (address1) VALUES ("Shipping Address - Address 1"); //// INSERT INTO "users" (name,billing_address_id,shipping_address_id) VALUES ("jinzhu", 1, 2);

//// INSERT INTO "emails" (user_id,email) VALUES (111, "jinzhu@https://www.360docs.net/doc/3c9174631.html,");

//// INSERT INTO "emails" (user_id,email) VALUES (111, "jinzhu-2@https://www.360docs.net/doc/3c9174631.html,"); //// INSERT INTO "languages" ("name") VALUES ('ZH');

//// INSERT INTO user_languages ("user_id","language_id") VALUES (111, 1);

//// INSERT INTO "languages" ("name") VALUES ('EN');

//// INSERT INTO user_languages ("user_id","language_id") VALUES (111, 2);

//// COMMIT;

db.Save(&user)

取消默认关联存储

type User struct {

gorm.Model

Namestring

CompanyIDuint

CompanyCompany`gorm:"save_associations:false"`

}

type Company struct {

gorm.Model

Namestring

}

或着手动取消

db.Set("gorm:save_associations", false).Create(&user)

db.Set("gorm:save_associations", false).Save(&user)

表间关系

一对多关系

type User struct {

gorm.Model

Emails []Email

}

type Email struct {

gorm.Model

Emailstring

UserIDuint

}

// 查询某userid为111的用户的所有Email地址db.Model(&user).Related(&emails) //// SELECT * FROM emails WHERE user_id = 111; // 111 is user's primary key 多对多关系

(相互关联）

type User struct {

gorm.Model

Languages []Language`gorm:"many2many:user_languages;"`

}

type Language struct {

gorm.Model

Namestring

Users []User`gorm:"many2many:user_languages;"`

}

// 查询某语言为111的所有用户db.Model(&language).Related(&users)

//// SELECT * FROM"users"INNERJOIN"user_languages"ON"user_languages"."user_id"

= "users"."id"WHERE ("user_languages"."language_id"IN ('111'))

（单一关联，比如个人与同学）

type User struct {

gorm.Model

Languages []Language`gorm:"many2many:user_languages;"`

}

type Language struct {

gorm.Model

Namestring

}

db.Model(&user).Related(&languages, "Languages")

//// SELECT * FROM"languages"INNERJOIN"user_languages"

ON"user_languages"."language_id" = "languages"."id"

WHERE"user_languages"."user_id" = 111

关联模式

（方便处理处理多对多）

// 开始关联db.Model(&user).Association("Languages")

// 查询db.Model(&user).Association("Languages").Find(&languages)

// 添加db.Model(&user).Association("Languages")

.Append([]Language{languageZH,

languageEN})db.Model(&user).Association("Languages").Append(Language{Name: "DE"})

// 删除db.Model(&user).Association("Languages")

.Delete([]Language{languageZH, languageEN})db.Model(&user)

.Association("Languages").Delete(languageZH, languageEN)

// 更新db.Model(&user).Association("Languages")

.Replace([]Language{languageZH,

languageEN})db.Model(&user).Association("Languages")

.Replace(Language{Name: "DE"}, languageEN)

db.Model(&user).Association("Languages").Count()

// 移除关联db.Model(&user).Association("Languages").Clear()

高级用法

事务

func CreateAnimals(db *gorm.DB) err {

tx := db.Begin()

// Note the use of tx as the database handle once you are within a transaction

if err := tx.Create(&Animal{Name: "Giraffe"}).Error; err != nil {

tx.Rollback()

return err

}

if err := tx.Create(&Animal{Name: "Lion"}).Error; err != nil {

tx.Rollback()

return err

}

https://www.360docs.net/doc/3c9174631.html,mit()

return nil

}

原生 sql

db.Exec("DROPTABLEusers;")

db.Exec("UPDATE orders SET shipped_at=? WHEREidIN (?)", time.Now(), []int64{11,22,33}) // Scantype Result struct {

Name string

Age int

}

var result Result

db.Raw("SELECTname, age FROMusersWHEREname = ?", 3).Scan(&result)

sql.DB 接口

// Get generic database object `*sql.DB` to use its functions

db.DB()

// Ping db.DB().Ping()

db.DB().SetMaxIdleConns(10)db.DB().SetMaxOpenConns(100)

日志处理

// Enable Logger, show detailed log db.LogMode(true)

// Diable Logger, don't show any log db.LogMode(false)

// Debug a single operation, show detailed log for this operation db.Debug() .Where("name = ?", "jinzhu").First(&User{})

//默认 error，设置日志级别db.SetLogger(gorm.Logger{revel.TRACE})

错误处理

// 一般处理if err := db.Where("name = ?", "jinzhu").First(&user).Error; err != nil { // error handling...

}

// 获取所有的错误

db.First(&user).Limit(10).Find(&users).GetErrors()

// 获取记录找不到错误（不排除有其他错误）

db.Where("name = ?", "hello world").First(&user).RecordNotFound()