Golang gorm one-to-one relationship

one-to-one relationship

---

There are relatively few one-to-one relationships. They are generally used for table extensions. For example, if a user table has many fields, it can be split into two tables. Commonly used fields are placed in the main table, and uncommon fields are placed in the details table.

For the user table, you can click userinfo through user.

 

Create table and insert data

package main

import (
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type Teacher struct {
	ID          int
	Name        string
	Age         int
	Gender      bool
	TeacherInfo TeacherInfo
}

type TeacherInfo struct {
	ID        int
	TeacherID int
	Address   string
	Hobby     string
}

func (*Teacher) TableName() string {
	return "teacher"
}

func (*TeacherInfo) TableName() string {
	return "teacherinfo"
}

func main() {
	dsn := "root:7PXjAkY!&nlR@tcp(192.168.11.128:3306)/test?charset=utf8mb4&parseTime=True&loc=Local"
	db, _ := gorm.Open(mysql.Open(dsn), &gorm.Config{})
	db.Debug().AutoMigrate(&Teacher{}, &TeacherInfo{})

	var teacherList []Teacher
	teacherList = append(teacherList, Teacher{
		Name:   "yanzi",
		Age:    28,
		Gender: false,
		TeacherInfo: TeacherInfo{
			Address: "hangzhou",
			Hobby:   "video",
		},
	}, Teacher{
		Name:   "lucas",
		Age:    30,
		Gender: false,
		TeacherInfo: TeacherInfo{
			Address: "hangzhou",
			Hobby:   "reading",
		},
	})

	db.Create(&teacherList)

}


mysql> desc teacher;
+--------+------------+------+-----+---------+----------------+
| Field  | Type       | Null | Key | Default | Extra          |
+--------+------------+------+-----+---------+----------------+
| id     | bigint     | NO   | PRI | NULL    | auto_increment |
| name   | longtext   | YES  |     | NULL    |                |
| age    | bigint     | YES  |     | NULL    |                |
| gender | tinyint(1) | YES  |     | NULL    |                |
+--------+------------+------+-----+---------+----------------+

mysql> desc teacherinfo;
+------------+----------+------+-----+---------+----------------+
| Field      | Type     | Null | Key | Default | Extra          |
+------------+----------+------+-----+---------+----------------+
| id         | bigint   | NO   | PRI | NULL    | auto_increment |
| teacher_id | bigint   | YES  | MUL | NULL    |                |
| address    | longtext | YES  |     | NULL    |                |
| hobby      | longtext | YES  |     | NULL    |                |
+------------+----------+------+-----+---------+----------------+

mysql> select * from teacher;
+----+-------+------+--------+
| id | name  | age  | gender |
+----+-------+------+--------+
|  1 | yanzi |   28 |      0 |
|  2 | lucas |   30 |      0 |
+----+-------+------+--------+

mysql> select * from teacherinfo;
+----+------------+----------+---------+
| id | teacher_id | address  | hobby   |
+----+------------+----------+---------+
|  1 |          1 | hangzhou | video   |
|  2 |          2 | hangzhou | reading |
+----+------------+----------+---------+

 You cannot query teacherinfo information by simply using take find.

	var t Teacher
	db.Take(&t)
	fmt.Println(t)

[4.938ms] [rows:-] SELECT count(*) FROM INFORMATION_SCHEMA.table_constraints WHERE constraint_schema = 'test' AND table_name = 'teacherinfo' AND co
nstraint_name = 'fk_teacher_teacher_info'
{1 yanzi 28 false {0 0  }}

If you want to query user details, use preload

	var t Teacher
	db.Debug().Preload("TeacherInfo").Take(&t)
	fmt.Println(t)

[1.226ms] [rows:1] SELECT * FROM `teacherinfo` WHERE `teacherinfo`.`teacher_id` = 1
[41.415ms] [rows:1] SELECT * FROM `teacher` LIMIT 1                            
{1 yanzi 28 false {1 1 hangzhou video}}  

 

 

delete

	var t Teacher
	db.Take(&t, 2)
	db.Debug().Select("TeacherInfo").Delete(&t)

[3.472ms] [rows:1] DELETE FROM `teacherinfo` WHERE `teacherinfo`.`teacher_id` = 2
[60.613ms] [rows:1] DELETE FROM `teacher` WHERE `teacher`.`id` = 2