gormExample/models.go

package gormExample

import (
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"log"
	"time"
)

type Content struct {
	gorm.Model

	Subject string
	Likes   uint `gorm:""`
	Views   uint `gorm:""`
	//Likes   uint `gorm:"default:99"`
	//Views       *uint `gorm:"default:99"`
	PublishTime *time.Time
	// 不需要迁移
	// 禁用写操作
	Sv string `gorm:"-:migration;<-:false"`

	// 作者ID
	AuthorID uint
}

//// Author模型
//type Author struct {
//	gorm.Model
//	Status int
//
//	Name  string
//	Email string
//}

type ContentStrPK struct {
	ID          string `gorm:"primaryKey"`
	Subject     string
	Likes       uint
	Views       uint
	PublishTime *time.Time
}

const (
	defaultViews = 99
	defaultLikes = 99
)

func NewContent() Content {
	return Content{
		Likes: defaultLikes,
		Views: defaultViews,
	}
}

// Hook
func (c *Content) BeforeCreate(db *gorm.DB) error {
	// 业务
	if c.PublishTime == nil {
		now := time.Now()
		c.PublishTime = &now
	}

	// 配置
	db.Statement.AddClause(clause.OnConflict{UpdateAll: true})

	log.Println("content before create hook")

	return nil
}

func (c *Content) AfterCreate(db *gorm.DB) error {
	//return errors.New("custom error")
	return nil
}

func (c *Content) AfterFind(db *gorm.DB) error {
	if c.AuthorID == 0 {
		c.AuthorID = 1 // 1， 假定的默认作者
	}

	return nil
}

// 作者模型
// Author模型
type Author struct {
	gorm.Model
	Status int
	Name   string
	Email  string

	// 积分
	Points int

	// 拥有多个论文内容
	// has many

	// 默认关联
	Essays []Essay `gorm:"constraint:OnDelete:SET NULL;"`

	// 第一作者论文列表
	FirstEssays []Essay `gorm:"foreignKey:FirstAuthorID;references:;"`
	// 第二作者论文列表
	SecondEssays []Essay `gorm:"foreignKey:SecondAuthorID;references:;"`
}

// CREATE TABLE `msb_essay` (
//  `id` bigint unsigned NOT NULL AUTO_INCREMENT,
//  `first_author_id` bigint unsigned DEFAULT NULL,
//  `second_author_id` bigint unsigned DEFAULT NULL,
//  `author_id` bigint unsigned DEFAULT NULL,
//  PRIMARY KEY (`id`),
//  KEY `idx_msb_essay_deleted_at` (`deleted_at`),
//  KEY `fk_msb_author_essays` (`author_id`),
//  KEY `fk_msb_author_first_essays` (`first_author_id`),
//  KEY `fk_msb_author_second_essays` (`second_author_id`),
//  CONSTRAINT `fk_msb_author_essays` FOREIGN KEY (`author_id`) REFERENCES `msb_author` (`id`),
//  CONSTRAINT `fk_msb_author_first_essays` FOREIGN KEY (`first_author_id`) REFERENCES `msb_author` (`id`),
//  CONSTRAINT `fk_msb_author_second_essays` FOREIGN KEY (`second_author_id`) REFERENCES `msb_author` (`id`)
//) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

// 论文内容
type Essay struct {
	gorm.Model
	Subject string
	Content string

	// 自定义关联字段
	FirstAuthorID  *uint
	SecondAuthorID *uint

	FirstAuthor  Author `gorm:"foreignKey:FirstAuthorID;references:;"`
	SecondAuthor Author `gorm:"foreignKey:SecondAuthorID;references:;"`

	// 外键字段
	AuthorID *uint
	// 属于某个作者
	// belongs to
	Author Author

	// 拥有一个论文元信息
	// has one
	EssayMate EssayMate

	// 拥有多个Tag
	// many to many
	Tags []Tag `gorm:"many2many:essay_tag"`
}

// 论文元信息
type EssayMate struct {
	gorm.Model
	Keyword     string
	Description string

	// 外键字段
	EssayID *uint

	// 属于一个论文内容，比较少用
	//Essay *Essay
}

type Tag struct {
	gorm.Model
	Title string

	// 拥有多个Essay
	// many to many
	Essays []Essay `gorm:"many2many:essay_tag"`
}