实体框架将本地数据添加到数据库列表中 [英] Entity Framework add local data to list from database

问题描述

我对Entity Framework还是很陌生，我正在使用此方法来查询数据库:

I am pretty new to Entity Framework and I am using this method in order to query through my database:

var _context = new StudioEntities();
var results = _context.tblStudios.Select(u => new
{
    u.Standort,
    u.Name,
    u.Id
}).ToList();

现在，我的目标是添加数据库中不存在的本地数据.我用这段代码尝试了一下，但是没有用:

Now my goal is to add local data as well which isn't present in the database. I tried it with this code but it didn't work:

results.Add(new tblStudio { Id = 0, Name = "Gesamt" });

有人可以帮我吗?谢谢

修改:

我的表类如下:

public partial class tblStudio
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Standort { get; set; }
    public Nullable<int> Plz { get; set; }
}

推荐答案

result不是tblStudios的List，而是Anonymous Type的List.因此，如果要将项目添加到result，则应这样做:

The result is not a List of tblStudios, it is a List of Anonymous Type. So if you want to add an item to the result you should do like this:

var results = _context.tblStudios.Select(u => new tblStudiosDTO()
{
    Standort = u.Standort,
    Name = u.Name,
    Id = u.Id
}).ToList();

results.Add(new tblStudiosDTO() { Id = "0", Name = "Gesamt" });

但是，由于无法投影到映射的实体上，因此需要使用tblStudios实体的所需属性创建像tblStudiosDTO这样的DTO类.

But because you cannot project onto a mapped entity then you need to create a DTO class like tblStudiosDTO with needed properties from the tblStudios entity.

public class tblStudiosDTO 
{
    public string Standort { get; set; }
    public string Name { get; set; }
    public string Id { get; set; }
}

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