南宁网站设计,seo优化流程,做微网站迅宇科技,广告设计专业可以考什么证一对多的添加有两种情况#xff1a;
一种是添加用户的时候同时创建文章其次是创建文章关联已经存在的用户。
package mainimport (gorm.io/driver/mysqlgorm.io/gorm
)// User 用户表 一个用户拥有多篇文章
type User struct {ID int64Name …
一对多的添加有两种情况
一种是添加用户的时候同时创建文章其次是创建文章关联已经存在的用户。
package mainimport (gorm.io/driver/mysqlgorm.io/gorm
)// User 用户表 一个用户拥有多篇文章
type User struct {ID int64Name string gorm:size:6Articles []Article //用户拥有的文章列表 has many
}type Article struct {ID int64 gorm:size:4Title string gorm:size:16UserID int64 //属于 belongs to
}func (*User) TableName() string {return user
}func (*Article) TableName() string {return article
}func main() {dsn : root:7PXjAkY!nlRtcp(192.168.11.128:3306)/test?charsetutf8mb4parseTimeTruelocLocaldb, _ : gorm.Open(mysql.Open(dsn), gorm.Config{})db.Debug().AutoMigrate(User{}, Article{})var u Usera1 : Article{Title: redis,}u User{Name: yanzi,Articles: []Article{{Title: golang,},{Title: k8s,},a1,},}db.Debug().Create(u)
}[8.981ms] [rows:3] INSERT INTO article (title,user_id) VALUES (golang,2),(k8s,2),(redis,2) ON DUPLICATE KEY UPDATE user_idVALUES(user
_id)[14.812ms] [rows:1] INSERT INTO user (name) VALUES (yanzi)
最后一种就是关联已有用户 var articles []Articlearticles []Article{{Title: cherry,UserID: 2,},{Title: marry,UserID: 2,},}db.Debug().Create(articles)[11.754ms] [rows:2] INSERT INTO article (title,user_id) VALUES (cherry,2),(marry,2) 外键添加 var u Userdb.Debug().Take(u, 3)var a Articledb.Debug().Take(a, 7)u.Articles []Article{a}db.Debug().Save(u)[1.300ms] [rows:1] SELECT * FROM user WHERE user.id 3 LIMIT 1[1.629ms] [rows:1] SELECT * FROM article WHERE article.id 7 LIMIT 1[2.901ms] [rows:2] INSERT INTO article (title,user_id,id) VALUES (marry,3,7) ON DUPLICATE KEY UPDATE user_idVALUES(user_id)[6.363ms] [rows:0] UPDATE user SET nametest WHERE id 3[0.557ms] [rows:0] INSERT INTO article (title,user_id,id) VALUES (marry,3,7) ON DUPLICATE KEY UPDATE user_idVALUES(user_id)[3.713ms] [rows:0] INSERT INTO user (name,id) VALUES (test,3) ON DUPLICATE KEY UPDATE nameVALUES(name)mysql select * from user;
-----------
| id | name |
-----------
| 1 | lucas |
| 2 | yanzi |
| 3 | test |
-----------
mysql select * from article;
---------------------
| id | title | user_id |
---------------------
| 1 | golang | 1 |
| 2 | k8s | 1 |
| 3 | golang | 2 |
| 4 | k8s | 2 |
| 5 | redis | 2 |
| 6 | cherry | 2 |
| 7 | marry | 3 |
--------------------- var u Userdb.Debug().Take(u, 3)var a Articledb.Debug().Take(a, 6)db.Debug().Model(u).Association(Articles).Append(a)[2.196ms] [rows:2] INSERT INTO article (title,user_id,id) VALUES (cherry,3,6) ON DUPLICATE KEY UPDATE user_idVALUES(user_id)
model是声明映射关系的对象类型通过这个对象类型找到表名和字段。 var u Userdb.Debug().Take(u, 3)var a Articledb.Debug().Take(a, 5)db.Debug().Model(u).Association(Articles).Append(a)[1.409ms] [rows:1] SELECT * FROM user WHERE user.id 3 LIMIT 1[1.254ms] [rows:1] SELECT * FROM article WHERE article.id 5 LIMIT 1[2.285ms] [rows:2] INSERT INTO article (title,user_id,id) VALUES (redis,3,5) ON DUPLICATE KEY UPDATE user_idVALUES(user_id)
