// 从地图创建
db.Model(User{}).Create( map [ string ] interface {}{ "Name" : "jinzhu" , "Location" : clause.Expr{SQL: "ST_PointFromText(?)" , Vars : [] interface {}{ "POINT(100 100)" }}, }) // INSERT INTO `users` (`name`,`location`) VALUES ("jinzhu",ST_PointFromText("POINT(100 100)" ));

//从定制数据类型创建
type Location struct {
  X, Y int
}

// Scan 实现了 sql.Scanner interface 
func  (loc *Location)  Scan (v interface {})  error { // 从数据库驱动程序扫描一个值到 struct }
  
func  (loc Location)  GormDataType ()  string { return "geometry" }
   
func  (loc Location)  GormValue (ctx context.Context, db *gorm.DB) clause.Expr { return clause.Expr{    SQL:   "ST_PointFromText(?)" ,    Vars: [] interface {}{fmt.Sprintf( "POINT(%d %d)" , loc.X, loc.Y)},  }}
  
type User struct {
   Name     string
  Location Location
}

db.Create(&User{ 
  Name:      "jinzhu" , 
  Location: Location{X: 100 , Y: 100 }, 
}) 
// INSERT INTO `users` (`name`,`location`) VALUES ("jinzhu",ST_PointFromText （“点（100 100）”））

先进的

用关联创建

当创建一些带有关联的数据时，如果它的关联值不是零值，这些关联将被更新，并且它的Hooks方法将被调用。

type CreditCard struct { 
  gorm.Model 
  Number    string
   UserID    uint
 }

type User struct { 
  gorm.Model 
  Name        string
   CreditCard CreditCard 
}

db.Create（用户{
  Name       ：“jinzhu”，
  CreditCard ：CreditCard{Number：“411111111111” } 
}）
// INSERT INTO`users` ... 
// INSERT INTO`credit_cards` ...

您可以跳过保存与Select, 的关联Omit，例如：

db.Omit( "CreditCard" ).Create(&user)

// 跳过所有关联
db.Omit(clause.Associations).Create(&user)

默认值

您可以为带有 tag 的字段定义默认值default，例如：

type User struct { 
  ID    int64
   Name string  `gorm:"default:galeone"`
   Age   int64   `gorm:"default:18"`
 }

type User struct { 
  gorm.Model 
  Name string
   Age * int            `gorm:"default:18"`
   Active sql.NullBool `gorm:"default:true"`
 }

type User struct { 
  ID         string  `gorm:"default:uuid_generate_v3()"`  // db func
   FirstName string
   LastName   string
   Age        uint8
   FullName   string  `gorm:"->;type:GENERATED ALWAYS AS (concat(firstname,' ',lastname ));默认值:(-);"`
 }

导入 “gorm.io/gorm/clause”

// 对冲突不做任何处理
db.Clauses(clause.OnConflict{DoNothing: true }).Create(&user)

// 在 `id` 冲突时将列更新为默认值
db.Clauses(clause.OnConflict{ 
  Columns: []clause.Column{{Name: "id" }}, 
  DoUpdates: clause.Assignments( map [ string ] interface {} { "role" : "user" }), 
}).Create(&users) 
// MERGE INTO "users" USING *** WHEN NOT MATCHED THEN INSERT *** WHEN MATCHED THEN UPDATE SET ***; SQL Server 
// INSERT INTO `users` *** ON DUPLICATE KEY UPDATE ***; MySQL

// 使用 SQL 表达式
db.Clauses(clause.OnConflict{ 
  Columns: []clause.Column{{Name: "id" }}, 
  DoUpdates: clause.Assignments( map [ string ] interface {}{ "count" : gorm. Expr( "GREATEST(count, VALUES(count))" )}), 
}).Create(&users) 
// INSERT INTO `users` *** ON DUPLICATE KEY UPDATE `count`=GREATEST(count, VALUES(count) );

// 在 `id` 冲突时将列更新为新值
db.Clauses(clause.OnConflict{ 
  Columns: []clause.Column{{Name: "id" }}, 
  DoUpdates: clause.AssignmentColumns([] string { "name" , "age" }), 
}).Create(&users) 
// 合并到 "users" 使用 *** WHEN NOT MATCHED THEN INSERT *** WHEN MATCHED THEN UPDATE SET "name"="excluded"."name"; SQL Server 
// INSERT INTO "users" *** ON CONFLICT ("id") DO UPDATE SET "name"="excluded"."name", "age"="excluded"."age"; PostgreSQL // INSERT INTO `users` *** ON DUPLICATE KEY UPDATE `name`=VALUES(name), `年龄=值（年龄）; MySQL


// 将除主键之外的所有列更新为冲突时的新值
db.Clauses(clause.OnConflict{ 
  UpdateAll: true , 
}).Create(&users) 
// INSERT INTO "users" *** ON CONFLICT ("id" ) DO UPDATE SET "name"="excluded"."name", "age"="excluded"."age", ...;