封装gorm的CRUD操作

1、新增

//新增一条数据
func CreateEntity(DBExecutor *gorm.DB, entity interface{}) error {
	if err := DBExecutor.Debug().Create(entity).Error; err != nil {
		return err
	}
	return nil
}

//    新增多条数据
func CreateEntities(DBExecutor *gorm.DB, entities interface{}) error {
	DBResult := DBExecutor.Create(entities)
	if err := DBResult.Error; err != nil {
		return err
	}
	return nil
}

2、删除

//  删除一条数据
func DeleteEntity(DBExecutor *gorm.DB, entity interface{}) (int64, error) {
	DBResult := DBExecutor.Unscoped().Where(entity).Delete(entity)
	if err := DBResult.Error; err != nil {
		return 0, err
	}
	return DBResult.RowsAffected, nil
}

//  删除多条数据
func DeleteEntities(DBExecutor *gorm.DB, filter *map[string]interface{}, entity interface{}) (int64, error) {
	query := DBExecutor.Unscoped()
	if filter != nil {
		for key, value := range *filter {
			switch {
			case strings.HasSuffix(key, "IN"):
				query = query.Where(key+" (?)", value)
			default:
				query = query.Where(key+" = ?", value)
			}
		}
	}
	result := query.Debug().Delete(entity)
	return result.RowsAffected, result.Error
}

3、查询

//    通过ID查询
func QueryEntity(entityID interface{}, entity interface{}) error {
	result := DB.Where("ID = ?", entityID).First(entity)
	if result.RowsAffected < 1 {
		return errors.New("查询结果为空")
	}
	return result.Error
}

//    带有group、order、where筛选条件的查询
func QueryEntityByFilter(filter *map[string]interface{}, entity interface{}) error {
	// 不存在时，不会返回错误
	query := DB.Select("*")
	if filter != nil {
		for key, value := range *filter {
			if key == "order" {
				query = query.Order(value)
			} else if key == "group" {
				query = query.Group(value.(string))
			} else {
				query = query.Where(key+" = ?", value)
			}
		}
	}
	result := query.Find(entity)
	return result.Error
}

　　

//    查询数目
func QueryCount(params *map[string]interface{}, list interface{}, count *int64) error {
	query := DB
	if params != nil {
		for key, value := range *params {
			switch {
			case strings.HasSuffix(key, "IN"):
				query = query.Where(key+" (?)", value)
			case key == "distinct":
				query = query.Distinct(value)
			case strings.HasSuffix(key, "!="):
				if value == "" {
					query = query.Where(key + " ''")
				} else if value == 0 {
					query = query.Where(key + " 0")
				} else {
					query = query.Where(key, value)
				}
			default:
				query = query.Where(key+" = ?", value)
			}
		}
	}
	if err := query.Find(list).Count(count).Error; err != nil {
		return err
	}
	return nil
}

　　

//    带筛选条件查询
func QueryList(params *map[string]interface{}, list interface{}) error {
	query := DB.Debug()
	if params != nil {
		for key, value := range *params {
			switch {
			case key == "select":
				valueStr := ""
				flagStr := ""
				for _, v := range value.([]string) {
					valueStr = valueStr + flagStr + v
					flagStr = " "
				}
				query = query.Select(valueStr)
			case key == "table":
				query = query.Table(value.(string))
			case key == "distinct":
				query = query.Distinct(value)
			case key == "order":
				query = query.Order(value)
			case key == "limit":
				query = query.Limit(value.(int))
			case key == "offset":
				query = query.Offset(value.(int))
			case strings.HasSuffix(key, "IN"):
				query = query.Where(key+" (?)", value)
			case strings.HasSuffix(key, "!="):
				if value == "" {
					query = query.Where(key + " ''")
				} else if value == 0 {
					query = query.Where(key + " 0")
				} else {
					query = query.Where(key, value)
				}
			case strings.HasSuffix(key, "?"):
				query = query.Where(key, value)
			case strings.HasSuffix(key, "LIKE"):
				query = query.Where(key+" ?", "%"+value.(string)+"%")
			case strings.Index(key, "LIKE") != -1:
				queryInfo := strings.SplitN(value.(string), " ", 2)
				query = query.Where(queryInfo[0]+" LIKE ?", "%"+queryInfo[1]+"%")
			case strings.HasSuffix(key, "BETWEEN"):
				values := strings.Split(value.(string), ",")
				query = query.Where(key+"? AND ?", values[0], values[1])
			default:
				query = query.Where(key+" = ?", value)
			}
		}
	}
	if err := query.Find(list).Error; err != nil {
		return err
	}
	return nil
}

//    查询并返回查询到的结果的总数
func QueryListReturnNumber(params *map[string]interface{}, list interface{}) (int64, error) {
	var total int64
	query := DB
	if params != nil {
		for key, value := range *params {
			switch {
			case key == "select":
				valueStr := ""
				flagStr := ""
				for _, v := range value.([]string) {
					valueStr = valueStr + flagStr + v
					flagStr = ","
				}
				query = query.Select(valueStr)
			case key == "distinct":
				query = query.Distinct(value)
			case key == "order":
				query = query.Order(value)
			case key == "limit":
				continue
				// query = query.Limit(value.(int))
			case key == "offset":
				continue
				// query = query.Offset(value.(int))
			case key == "time":
				query = query.Where("created_at >= ? AND created_at <= ?", value.([]time.Time)[0], value.([]time.Time)[1])
			case key == "data_time":
				query = query.Where("data_time >= ? AND data_time <= ?", value.([]time.Time)[0], value.([]time.Time)[1])
			case strings.Index(key, "LIKE") != -1:
				queryInfo := strings.Split(value.(string), " ")
				query = query.Where(queryInfo[0]+" LIKE ?", "%"+queryInfo[1]+"%")
			case strings.HasSuffix(key, "BETWEEN"):
				values := strings.Split(value.(string), ",")
				query = query.Where("? between ? AND ?", values[0], values[1], values[2])
			case strings.HasSuffix(key, "?"):
				query = query.Where(key, value)
			case strings.HasSuffix(key, "IN"):
				query = query.Where(key+" (?)", value)
			default:
				query = query.Where(key+" = ?", value)
			}
		}
		// 这里为了获取分页前结果的总个数，给前端计算页数使用
		total = query.Find(list).RowsAffected
		for key, value := range *params {
			if key == "limit" {
				query = query.Limit(value.(int))
			} else if key == "offset" {
				query = query.Offset(value.(int))
			} else {
				continue
			}
		}
	}
	if err := query.Debug().Find(list).Error; err != nil {
		return 0, err
	}
	return total, nil
}

　　

// 关联查询
type result struct {
		dal.Comment
		User1Name string `json:"user1_name"`
		User2Name string `json:"user2_name"`
	}
	var res []*result
	err = dal.DB.Table("comments").Select("comments.*,u1.name as user1_name,u2.name as user2_name").
		Joins("left join users as u1 on u1.id = comments.user1_id").
		Joins("left join users as u2 on u2.id = comments.user2_id").
		Where("comments.user1_id = ? or comments.user2_id = ?",int(m["user_id"].(float64)),int(m["user_id"].(float64))).
		Where("comments.status = 2").
		Scan(&res).Error
	if err!=nil{
		log.Printf("get comment error:unit not exist:%v", err)
		c.JSON(404, gin.H{
			"message":"comment not exist",
		})
		return
	}

　　

　　

4、更新

//    更新多条数据
func UpdateEntities(DBExecutor *gorm.DB, entities interface{}) error {
	result := DBExecutor.Save(entities)
	if err := result.Error; err != nil {
		return err
	}
	return nil
}

　　

//    更新指定字段
func UpdateFields(DBExecutor *gorm.DB, model interface{}, selector *map[string]interface{}, fields *map[string]interface{}) error {
	query := DBExecutor.Model(&model)
	if selector != nil {
		for key, value := range *selector {
			switch {
			case key == "order":
			case strings.HasSuffix(key, "IN"):
				query = query.Where(key+" (?)", value)
			default:
				query = query.Where(key+" = ?", value)
			}
		}
	}
	result := query.Updates(fields)
	if err := result.Error; err != nil {
		return err
	}
	return nil
}

　　

//    更新单条数据
func UpdateEntity(DBExecutor *gorm.DB, entity interface{}) error {
	result := DBExecutor.Model(entity).Updates(entity)
	if err := result.Error; err != nil {
		return err
	}
	return nil
}

　　

//    根据ID筛选更新数据
func UpdateEntityByID(DBExecutor *gorm.DB, ID uint, entity interface{}) error {
	result := DBExecutor.Model(entity).Where("id = ?", ID).Updates(entity)
	if err := result.Error; err != nil {
		return err
	}
	return nil
}

　　

//    查询到结果就返回，否则插入新数据
func GetOrCreate(DBExecutor *gorm.DB, entity interface{}) (int64, error) {
	// 返回的int, 表示查询到的个数, 0则代表查询无果，创建之
	result := DBExecutor.Where(entity).Limit(1).Find(entity)
	if err = result.Error; err != nil {
		return 0, err
	}
	if result.RowsAffected == 0 {
		err = CreateEntity(DBExecutor, entity)
		if err != nil {
			return 0, err
		}
		return 0, nil
	}
	return result.RowsAffected, nil
}

　　

//    数据已存在就更新，否则创建
func UpdateOrCreate(DBExecutor *gorm.DB, entity interface{}) error {
	result := DBExecutor.Where(entity).Limit(1).Find(entity)
	if err = result.Error; err != nil {
		return err
	}
	if result.RowsAffected == 0 {
		err = CreateEntity(DBExecutor, entity)
		if err != nil {
			return err
		}
	} else if result.RowsAffected == 1 {
		result = DBExecutor.Model(entity).Updates(entity)
		if err := result.Error; err != nil {
			return err
		}
	}
	return nil
}