Dapper强类型查询返回默认对象值

问题描述

刚开始使用Dapper并喜欢它.我遇到了问题，它返回了正确数量的对象，但是它们的属性都具有默认值

just started to use Dapper and like it.I'm having a problem with it, it returns the right number of objects, butthey all have default values for their properties

using (var dbConnection = Connection)
        {
            await dbConnection.OpenAsync();

            const string sQuery2 = @"SELECT * FROM ChipTime WHERE MacAddress = @MacAddress AND ClientId = @ClientId ORDER BY CreateDate Desc";
            var chipTimes = dbConnection.Query<ChipTime>(sQuery2, new { ClientId = clientId, MacAddress = id }).ToList();
        }

chipTimes只是一个ChipTime对象的列表，所有这些对象都具有默认属性，而不是数据库中的值

chipTimes just has a list of ChipTime objects, all of which just have the default properties and not the values from the database

如果我这样做

using (var dbConnection = Connection)
        {
            await dbConnection.OpenAsync();

            const string sQuery2 =
                @"SELECT * FROM ChipTime WHERE MacAddress = @MacAddress AND ClientId = @ClientId ORDER BY CreateDate Desc";
            var chipTimes = dbConnection.Query(sQuery2, new {ClientId = clientId, MacAddress = id}).ToList();
        }

所有动态参数都具有正确的值

The dynamics all have the right values in

ChipTime类非常简单

ChipTime class is really simple

    public class ChipTime
{
    public int TimeId { get; set; }
    public string TimingPoint { get; set; }
    public string MacAddress { get; set; }
    public string ChipCode { get; set; }
    public DateTime ChipDateTime { get; set; }
    public DateTime ReaderTime { get; set; }
    public int ReaderTimeDec { get; set; }
    public string UhfReaderNo { get; set; }
    public string Rssi { get; set; }
    public DateTime CreateDate{ get; set; }
    public int ReplStatus { get; set; }
    public int RaceId { get; set; }
    public int ClientId { get; set; }
    public int RecordNo { get; set; }
    public string AntennaNo { get; set; }
    public bool IsRaceNo { get; set; }

}

我在做什么错了?

推荐答案

尝试指定要在查询中选择的列的名称，而不要执行SELECT *:

Try to specify the names of columns that you want to select in your query instead of doing a SELECT *:

const string sQuery2 = @"SELECT TimeId, TimingPoint, MacAddress, ChipCode, ... FROM ChipTime WHERE MacAddress = @MacAddress AND ClientId = @ClientId ORDER BY CreateDate Desc";

为什么SELECT *被认为有害?

确保ChipTime表中的列与ChipTime类的属性名称完全匹配，并指定类型参数(dbConnection.Query < ChipTime> ):

Make sure that the columns in your ChipTime table exactly matches the property names of your ChipTime class and specify the type argument (dbConnection.Query <ChipTime>):

using (var dbConnection = Connection)
    {
        await dbConnection.OpenAsync();

        const string sQuery2 =
            @"SELECT TimeId, TimingPoint, MacAddress, ChipCode, ... FROM ChipTime WHERE MacAddress = @MacAddress AND ClientId = @ClientId ORDER BY CreateDate Desc";
        var chipTimes = dbConnection.Query<ChipTime>(sQuery2, new {ClientId = clientId, MacAddress = id}).ToList();
    }

这篇关于Dapper强类型查询返回默认对象值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！