gorm标签设置

• 设置缺省值(default:'galeone')

  当model字段中存在外键时，插入数据时又为空时，报错：

  type School struct{
        SchId    int     `json:"SchId"      gorm:"column:SchId;type:int;size:11;not null;primary_key;AUTO_INCREMENT;"`
    Name      string  `json:"Name"        gorm:"column:Name;type:varchar;size:500;not null;default:'galeone'"`
  }
  type Stu struct{
      StuId    int     `json:"SchId"      gorm:"column:SchId;type:int;size:11;not null;primary_key;AUTO_INCREMENT;"`
    Name      string  `json:"Name"        gorm:"column:Name;type:varchar;size:500;not null;"`
        SchId    int     `json:"SchId"      gorm:"column:SchId;type:int;size:11;"`
  }
  

  func main() {
    addModel := model.Stu{
        StuId: 1111,
        Name:   "xj",
    }
      err:=dao.insert(&addModel)
      if err.Error!=nil{
          fmt.Println(err)
      }
  }
  

  Error 1452: Cannot add or update a child row: a foreign key constraint fails 
  (`ew_nfdas`.`stu`, CONSTRAINT `fk_stud_schid` FOREIGN KEY (`SchId`) REFERENCES `school` (`SchId`) ON DELETE SET NULL ON UPDATE SET NULL) 
  
  

  插入语句：

  INSERT INTO stu (StuId,Name,SchId) VALUES (1111,'xj',0)

  由于SchId为外键，0值插入报错不存在

  正确的sql:

  INSERT INTO stu (StuId,Name) VALUES (1111,'xj')

  在字段标签gorm中添加==default:'galeone'==