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Golang Gorm实现自定义多态模型关联查询

article 2024/12/25 2:29:55
一、表结构
CREATE TABLE `orders` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `order_no` varchar(32) NOT NULL DEFAULT '',
  `orderable_id` int unsigned NOT NULL DEFAULT '0',
  `orderable_type` char(30) NOT NULL DEFAULT '',
  `status` tinyint unsigned NOT NULL DEFAULT '0',
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  `deleted_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

CREATE TABLE `phone` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `phone_name` varchar(50) NOT NULL DEFAULT '',
  `phone_model` varchar(30) NOT NULL DEFAULT '',
  `status` tinyint unsigned NOT NULL DEFAULT '0',
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  `deleted_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1003 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

CREATE TABLE `cars` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `car_name` varchar(50) NOT NULL DEFAULT '',
  `car_model` varchar(30) NOT NULL DEFAULT '',
  `status` tinyint unsigned NOT NULL DEFAULT '0',
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  `deleted_at` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1003 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
二、接口定义
// LoaderAble 接口定义数据加载行为
type LoaderAble interface {
	LoadAble(IDs []int) (map[int]any, error)
}

// LoadAbleItem 接口定义了可加载项的通用方法
type LoadAbleItem interface {
	GetAbleType() string        // 获取类型键值
	GetAbleID() int             // 获取ID
	SetLoadedAbleData(data any) // 设置加载的数据
}
三、模型定义并实现接口
type Order struct {
	Id            int            `json:"id"`
	OrderNo       string         `json:"order_no"`
	OrderableId   int            `json:"orderable_id"`
	OrderableType string         `json:"orderable_type"`
	Orderable     any            `json:"orderable" gorm:"-"`
	Status        uint8          `json:"status"`
	CreatedAt     *time.Time     `json:"created_at"`
	UpdatedAt     *time.Time     `json:"updated_at"`
	DeletedAt     gorm.DeletedAt `json:"deleted_at"`
}

func (tb *Order) TableName() string {
	return "orders"
}

func (tb *Order) GetAbleType() string {
	return tb.OrderableType
}

func (tb *Order) GetAbleID() int {
	return tb.OrderableId
}

func (tb *Order) SetLoadedAbleData(data any) {
	tb.Orderable = data
}



//--------------------------------------分割线--------------------------------------


type Car struct {
	Id        int            `json:"id"`
	CarName   string         `json:"car_name"`
	CarModel  string         `json:"car_model"`
	Status    uint8          `json:"status"`
	CreatedAt *time.Time     `json:"created_at"`
	UpdatedAt *time.Time     `json:"updated_at"`
	DeletedAt gorm.DeletedAt `json:"deleted_at"`
}

func (tb *Car) TableName() string {
	return "cars"
}

// CarLoaderAble 实现 Loader 接口
type CarLoaderAble struct{}

// LoadAble 具体实现加载多态关联逻辑
// IDs 多态关联类型ID(主要参数)
func (loader *CarLoaderAble) LoadAble(IDs []int) (resultMap map[int]any, err error) {
	IDsLen := len(IDs)
	if IDsLen == 0 {
		return
	}

	car := make([]*Car, 0, IDsLen)
	err = mysql.DefaultMysql.Db.Debug().Where("id IN (?) AND status = ?", IDs, 1).Find(&car).Error
	if err != nil {
		return
	}

	resultMap = make(map[int]any, IDsLen)
	for _, item := range car {
		resultMap[item.Id] = item
	}
	return
}


//--------------------------------------分割线--------------------------------------


type Phone struct {
	Id         int            `json:"id"`
	PhoneName  string         `json:"phone_name"`
	PhoneModel string         `json:"phone_model"`
	Status     uint8          `json:"status"`
	CreatedAt  *time.Time     `json:"created_at"`
	UpdatedAt  *time.Time     `json:"updated_at"`
	DeletedAt  gorm.DeletedAt `json:"deleted_at"`
}

func (tb *Phone) TableName() string {
	return "phone"
}


// PhoneLoaderAble 实现 Loader 接口
type PhoneLoaderAble struct{}

// LoadAble 具体实现加载多态关联逻辑
// IDs 多态关联类型ID(主要参数)
func (loader *PhoneLoaderAble) LoadAble(IDs []int) (resultMap map[int]any, err error) {
	IDsLen := len(IDs)
	if IDsLen == 0 {
		return
	}

	phone := make([]*Phone, 0, IDsLen)
	err = mysql.DefaultMysql.Db.Debug().Where("id IN (?) AND status = ?", IDs, 1).Find(&phone).Error
	if err != nil {
		return
	}

	resultMap = make(map[int]any, IDsLen)
	for _, item := range phone {
		resultMap[item.Id] = item
	}
	return
}
四、创建loader预加载器
// LoaderAbleFactory 用于管理不同类型的加载器
type LoaderAbleFactory struct {
	loaders map[string]LoaderAble
}

func NewLoaderAbleFactory() *LoaderAbleFactory {
	return &LoaderAbleFactory{
		loaders: make(map[string]LoaderAble),
	}
}

func (f *LoaderAbleFactory) RegisterLoader(typeName string, loader LoaderAble) {
	f.loaders[typeName] = loader
}
五、注册loader预加载器服务
var (
	loaderAbleFactory *LoaderAbleFactory
)

// init 选择在项目启动初始化时进行全局加载
func init() {
	loaderAbleFactory = NewLoaderAbleFactory()
	loaderAbleFactory.RegisterLoader("phone", &PhoneLoaderAble{})
	loaderAbleFactory.RegisterLoader("car", &CarLoaderAble{})
	log.Println("多态模型关系注册成功...")
}
六、实现LoadAble通用的加载函数
// LoadAble 通用的加载函数，可以处理任何实现了 LoadableItem 接口的切片
func LoadAble[T LoadAbleItem](items []T) error {
	if len(items) == 0 {
		return nil
	}

	// 按类型分组收集ID
	typeIDsMap := make(map[string][]int)
	for _, item := range items {
		typeKey := item.GetAbleType()
		typeIDsMap[typeKey] = append(typeIDsMap[typeKey], item.GetAbleID())
	}

	// 使用对应的loader加载数据
	typeDataMap := make(map[string]map[int]any)
	for typeName, ids := range typeIDsMap {
		loader, ok := loaderAbleFactory.loaders[typeName]
		if !ok {
			continue
		}

		resultMap, err := loader.LoadAble(ids)
		if err != nil {
			return err
		}
		typeDataMap[typeName] = resultMap
	}

	// 填充数据
	for _, item := range items {
		if dataMap, ok := typeDataMap[item.GetAbleType()]; ok {
			if data, exists := dataMap[item.GetAbleID()]; exists {
				item.SetLoadedAbleData(data)
			}
		}
	}
	return nil
}
七、调试
  1. 准备数据
--orders表
INSERT INTO `orders` (`id`, `order_no`, `orderable_id`, `orderable_type`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1, '202411010001', 1002, 'car', 1, '2024-11-01 12:03:03', '2024-11-01 12:03:06', NULL);
INSERT INTO `orders` (`id`, `order_no`, `orderable_id`, `orderable_type`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (2, '202411010002', 1001, 'phone', 1, '2024-11-01 12:03:03', '2024-11-01 12:03:06', NULL);
INSERT INTO `orders` (`id`, `order_no`, `orderable_id`, `orderable_type`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (3, '202411010003', 1000, 'car', 1, '2024-11-01 12:03:03', '2024-11-01 12:03:06', NULL);
INSERT INTO `orders` (`id`, `order_no`, `orderable_id`, `orderable_type`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (4, '202411010004', 1001, 'car', 1, '2024-11-01 12:03:03', '2024-11-01 12:03:06', NULL);
INSERT INTO `orders` (`id`, `order_no`, `orderable_id`, `orderable_type`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (5, '202411010005', 1002, 'phone', 1, '2024-11-01 12:03:03', '2024-11-01 12:03:06', NULL);

--phone表
INSERT INTO `phone` (`id`, `phone_name`, `phone_model`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1000, 'XiaoMi', '2S', 2, '2024-11-01 11:59:37', '2024-11-01 11:59:40', NULL);
INSERT INTO `phone` (`id`, `phone_name`, `phone_model`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1001, 'HUAWEI', 'mate60', 1, '2024-11-01 11:59:54', '2024-11-01 11:59:57', NULL);
INSERT INTO `phone` (`id`, `phone_name`, `phone_model`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1002, 'Apple', 'iPhone 12 Pro Max', 1, '2024-11-01 12:00:26', '2024-11-01 12:00:28', NULL);

--cars表
INSERT INTO `cars` (`id`, `car_name`, `car_model`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1000, '奥迪', 'A6L', 1, '2024-11-01 11:57:53', '2024-11-01 11:57:55', NULL);
INSERT INTO `cars` (`id`, `car_name`, `car_model`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1001, '宝马', '5系', 1, '2024-11-01 11:58:12', '2024-11-01 11:58:15', NULL);
INSERT INTO `cars` (`id`, `car_name`, `car_model`, `status`, `created_at`, `updated_at`, `deleted_at`) VALUES (1002, '奔驰', 'E300', 1, '2024-11-01 11:58:53', '2024-11-01 11:58:56', NULL);

        2. 编写代码

// Gin框架+Gorm为例
api.GET("/orders", controller.GetOrderList)

// GetOrderList 获取订单列表接口
func GetOrderList(c *gin.Context) {
	orders := make([]*model.Order, 0)
	err := mysql.DefaultMysql.Db.Debug().Find(&orders).Error
	if err != nil {
		c.JSON(200, gin.H{"error": err.Error()})
		return
	}
	err = model.LoadAble(orders)
	if err != nil {
		c.JSON(200, gin.H{"error": err.Error()})
		return
	}
	c.JSON(200, gin.H{"data": orders})
}

        3. 发起请求

curl '127.0.0.1:16888/api/orders'
{
    "data": [
        {
            "id": 1,
            "order_no": "202411010001",
            "orderable_id": 1002,
            "orderable_type": "car",
            "orderable": {
                "id": 1002,
                "car_name": "奔驰",
                "car_model": "E300",
                "status": 1,
                "created_at": "2024-11-01T11:58:53+08:00",
                "updated_at": "2024-11-01T11:58:56+08:00",
                "deleted_at": null
            },
            "status": 1,
            "created_at": "2024-11-01T12:03:03+08:00",
            "updated_at": "2024-11-01T12:03:06+08:00",
            "deleted_at": null
        },
        {
            "id": 2,
            "order_no": "202411010002",
            "orderable_id": 1001,
            "orderable_type": "phone",
            "orderable": {
                "id": 1001,
                "phone_name": "HUAWEI",
                "phone_model": "mate60",
                "status": 1,
                "status_new": 1,
                "created_at": "2024-11-01T11:59:54+08:00",
                "updated_at": "2024-11-01T11:59:57+08:00",
                "deleted_at": null
            },
            "status": 1,
            "created_at": "2024-11-01T12:03:03+08:00",
            "updated_at": "2024-11-01T12:03:06+08:00",
            "deleted_at": null
        },
        {
            "id": 3,
            "order_no": "202411010003",
            "orderable_id": 1000,
            "orderable_type": "car",
            "orderable": {
                "id": 1000,
                "car_name": "奥迪",
                "car_model": "A6L",
                "status": 1,
                "created_at": "2024-11-01T11:57:53+08:00",
                "updated_at": "2024-11-01T11:57:55+08:00",
                "deleted_at": null
            },
            "status": 1,
            "created_at": "2024-11-01T12:03:03+08:00",
            "updated_at": "2024-11-01T12:03:06+08:00",
            "deleted_at": null
        },
        {
            "id": 4,
            "order_no": "202411010004",
            "orderable_id": 1001,
            "orderable_type": "car",
            "orderable": {
                "id": 1001,
                "car_name": "宝马",
                "car_model": "5系",
                "status": 1,
                "created_at": "2024-11-01T11:58:12+08:00",
                "updated_at": "2024-11-01T11:58:15+08:00",
                "deleted_at": null
            },
            "status": 1,
            "created_at": "2024-11-01T12:03:03+08:00",
            "updated_at": "2024-11-01T12:03:06+08:00",
            "deleted_at": null
        },
        {
            "id": 5,
            "order_no": "202411010005",
            "orderable_id": 1002,
            "orderable_type": "phone",
            "orderable": {
                "id": 1002,
                "phone_name": "Apple",
                "phone_model": "iPhone 12 Pro Max",
                "status": 1,
                "status_new": 1,
                "created_at": "2024-11-01T12:00:26+08:00",
                "updated_at": "2024-11-01T12:00:28+08:00",
                "deleted_at": null
            },
            "status": 1,
            "created_at": "2024-11-01T12:03:03+08:00",
            "updated_at": "2024-11-01T12:03:06+08:00",
            "deleted_at": null
        }
    ]
}


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