项目中的dao层，我们用来查询数据库，获取想要数据。有时我们会需要查询数据给结构体赋值，并返回一个结构体指针，如下

func GetCommunityDetailByID(id int64) (communityDetail *models.CommunityDetail, err error) {
    sqlStr := `SELECT community_id,community_name,introduction,create_time FROM community WHERE community_id = ?`
    if err = db.Get(&communityDetail, sqlStr, id); err != nil {
        if err == sql.ErrNoRows {
            zap.L().Warn("there is no community_id in db.", zap.Error(err))
            err = ErrorInvalidID
        }
    }
    return
}

这样的代码看似没有问题，但其实并不正确，运行结果如下

2022-12-17T13:15:30.008+0800    ERROR   controller/community.go:37      logic.GetCommunityDetail() failed.      {"error": "scannable dest type ptr with >1 columns (4) in result"}

解决方法

出现上面的问题是因为在函数返回值处，我们只是声明了一个指针model.CommunityDetail类型的指针community，要使用这个指针给结构体赋值之前我们需要先对其进行初始化

func GetCommunityDetailByID(id int64) (communityDetail *models.CommunityDetail, err error) {
    communityDetail = new(models.CommunityDetail)
    sqlStr := `SELECT community_id,community_name,introduction,create_time FROM community WHERE community_id = ?`
    if err = db.Get(communityDetail, sqlStr, id); err != nil {
        if err == sql.ErrNoRows {
            zap.L().Warn("there is no community_id in db.", zap.Error(err))
            err = ErrorInvalidID
        }
    }
    return
}