如何向List< Products>添加一列？ ？ [英] How can I add one more column to List<Products> ?

问题描述

我在db中有一个数据表。

I have a data table in db.

ID || ProductName  || SoldDateTime
==================================
1  || Books         || 6543213571
2  || Pencils       || 1594563215
3  || Paint         || 5411865446
4  || Markers       || 2421375125
5  || Copies        || 5546423010
.  || .             || 7568714312

我在项目中添加了它作为ProdutEntityModel



现在我想将SoldDateTime转换为01/24/2015，结果我想要List< product>我怎样才能实现这个目标。

I added it in my project as ProdutEntityModel

Now i want to convert SoldDateTime into 01/24/2015 and the resultant i want List<product> how can i achieve this.

ID || ProductName  || SoldDateTime ||      SDateTime
==========================================================
1  || Books         || 6543213571  || 01/01/2015  06:22:15
2  || Pencils       || 1594563215  || 01/08/2015  15:25:55
3  || Paint         || 5411865446  || 01/15/2015  23:45:32
4  || Markers       || 2421375125  || 01/22/2015  00:56:33
5  || Copies        || 5546423010  || 02/12/2015  18:04:50
.  || .             || .           || .

如何在Linq to Entity中执行此操作。

How can i do this in Linq to Entity.

推荐答案

这是这样的： http://robbincremers.me/2012/01/31/entity-framework-using-partial-classes-to-add-business-logic-and-validation-to-generated-entities/ [ ^ ]

根据我的理解，您可以通过两种方式实现：

1。添加部分类

通过 Zoltan Zorgo [ ^ ]

或

2。将未映射的字段添加到您的模型

As per my understanding, you can achieve that using 2 ways:
1. add partial class
See solution 1 by Zoltan Zorgo[^]
or
2. add not mapped field to your model

[NotMapped]
public DateTime SDateTime {get; set;}

但你标记了你的问题： Linq ，所以这可能意味着你想根据你的模型创建查询...

But you tag your question: Linq, so it might means you want to create query based on your model...

var qry = from emd in EntityModelData
        select new {
            //get collection of your fields
            ID = ID,
            ProductName = ProductName,
            SoldDateTime = SoldDateTime,
            SDateTime = YourExtensionMethodToConvert(SoldDateTime)
        };

第一步：只选择所需数据。

Step1: Select only the required data.

 List<products> prodlist = ctx.Products
                          .Where(
                          x => SqlFunctions.DateAdd("s", x.SoldDateTime , "1970-01-01").Value.Year==DateTime.Now.Year &&
                           SqlFunctions.DateAdd("s", x.SoldDateTime , "1970-01-01").Value.Month==DateTime.Now.Month  ).ToList();
                                               
                                              
</products>

Step2：我添加了Partial Class而不是Mapped Property

Step2: I added Partial Class and not Mapped Property

namespace MyShop
{
  public partial class Products
  {
    private DateTime s_date = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
    public DateTime SDateTime
    { 
      get 
      {
        return s_date.AddSeconds(Convert.ToDouble(this.SoldDateTime)).ToLocalTime();
      }
    } 
  }
}

我要感谢Zoltan Zorgo获取此帮助。

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