Gorm Association summary

Manual address

Database design

 surface 1:
CREATE TABLE `blog_user` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `username` varchar(50) COLLATE utf8mb4_general_ci NOT NULL DEFAULT '',
  `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '',
  `created_at` datetime(3) DEFAULT NULL,
  `updated_at` datetime(3) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `idx_blog_user_created_at` (`created_at`),
  KEY `idx_blog_user_updated_at` (`updated_at`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

--------------------------------------------------------------------------------------------------------------------
 surface 2:
CREATE TABLE `blog_article` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `title` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '',
  `user_id` bigint unsigned NOT NULL,
  `is_hot` tinyint NOT NULL,
  `created_at` datetime(3) DEFAULT NULL,
  `updated_at` datetime(3) DEFAULT NULL,
  `deleted_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=15 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

1.Belongs To Belong to

The relationship between users and articles The article table exists in the user table id As Foreign keys , article Belong to user

1-1 User Of Model Structure

type User struct {
	models.BaseModel
	UserName string          `gorm:"column:username;" json:"username"`
	Password string          `json:"-"`
	models.CommonTimestampsField
}

1-2 Article Of Model Structure

type Article struct {
	models.BaseModel
	Title  string `json:"title"`
	IsHot  int8   `json:"is_hot"`
	UserId int64  `json:"user_id"` // Foreign keys 
	User   users.User `json:"user" gorm:"ForeignKey:UserId"`// Associated object 
}

Inquire about :

Joins or Preload Preloading

var results []Article
database.DB.Model(&Article{}).Joins("User").Find(&results).Error, results

---

2. hasOne one-on-one

The relationship between users and articles The article table exists in the user table id As Foreign keys , user And article one-on-one ( Assume One can only have one piece of article )

2-1 User Of Model Structure

type User struct {
	models.BaseModel
	UserName string          `gorm:"column:username;" json:"username"`
	Password string          `json:"-"`
	Article  article.Article `gorm:"foreignKey:UserId"`// One to one connection  
	models.CommonTimestampsField
}

2-2 Article Of Model Structure

type Article struct {
	models.BaseModel
	Title  string `json:"title"`
	IsHot  int8   `json:"is_hot"`
	UserId int64  `json:"user_id"` // Foreign keys 
}

Inquire about :

Preload Preloading

var results []Article
database.DB.Model(&User{}).Preload("Article").Find(&results).Error, results

---

3.Has Many One to many The relationship between users and articles The article table exists in the user table id As Foreign keys , user And article One to many

3-1 User Of Model Structure

type User struct {
	models.BaseModel
	UserName string          `gorm:"column:username;" json:"username"`
	Password string          `json:"-"`
	Article  []article.Article `gorm:"foreignKey:UserId"`
	models.CommonTimestampsField
}

3-2 Article Of Model Structure

type Article struct {
	models.BaseModel
	Title  string `json:"title"`
	IsHot  int8   `json:"is_hot"`
	UserId int64  `json:"user_id"` // Foreign keys 
}

Inquire about :

Preload Preloading

var results []Article
database.DB.Model(&User{}).Preload("Article").Find(&results).Error, results

---

4.Many To Many

4-1. newly added It's the body surface language & blog_user_has_language

CREATE TABLE `blog_language` (
  `id` int NOT NULL AUTO_INCREMENT,
  `title` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '',
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL,
  `deleted_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

------------------------------------------------------------------------------------
CREATE TABLE `blog_user_has_language` (
  `user_id` int NOT NULL DEFAULT '0',
  `language_id` int NOT NULL DEFAULT '0'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

4-2. Structure

type User struct {
	models.BaseModel
	UserName  string              `gorm:"column:username;" json:"username"`
	Password  string              `json:"-"`
	Languages []language.Language `gorm:"many2many:user_has_language;"`
	models.CommonTimestampsField
}

4-3. Inquire about ：

Preload Preloading

var results []Article
database.DB.Model(&User{}).Preload("Languages").Find(&results).Error, results