Linq投影嵌套LIST<；T>；所有物

本文关键字：gt 所有物 投影 lt LIST Linq 嵌套 | 更新日期: 2023-09-27 18:22:46

这个查询花了几天时间，但我几乎完成了。我已经破解了LINQ到实体的方法，通过阅读大量教程得出了以下内容。然而，我遗漏了最后一部分。

我有两个基本对象：

public class DashboardNavigation()
{
   public int Id {get; set;}
   public string Name {get; set;}
   .....etc.....
   public List<SubNav> SubDashNav {get; set;}
}
public class SubNav()
{
   ....properties....
}


var query = _mlsDashboardNavRepository.Table
        .OrderBy(x => x.Id)
        .Select(x => new
        {
            Id = x.Id,
            Name = x.Name,
            Description = x.Description,
            ImageUrl = x.ImageUrl,
            SubDashNav = _mlsSubDashNav.Table
                .Where(s => s.DashId == x.Id)
                .Select(y => new { Id = y.Id, DashId = y.DashId, Name = y.Name, Description = y.Description, ImageUrl = y.ImageUrl, IsAdvanced = y.IsAdvanced }).ToList()
        }).ToList().Select(q => new MLS_DashboardNavigation()
                            {
                                Id = q.Id,
                                Name = q.Name,
                                Description = q.Description,
                                ImageUrl = q.ImageUrl,
                                SubDashNav = ...???
                            }).ToList();

我的Linq正确地投影了DashboardNavigation，但我不知道如何填充SubDashNav？？？

Linq投影嵌套LIST<；T>；所有物

您不需要选择两次。我认为这也有同样的作用。

var query = _mlsDashboardNavRepository.Table
    .OrderBy(x => x.Id)
    .Select(x => new MLS_DashboardNavigation()
    {
        Id = x.Id,
        Name = x.Name,
        Description = x.Description,
        ImageUrl = x.ImageUrl,
        SubDashNav = _mlsSubDashNav.Table
            .Where(s => s.DashId == x.Id).ToList()
    }).ToList();

如果您使用实体框架和导航属性与DashIs作为子NavDash表的外键，那么您甚至可以执行此

var query = _mlsDashboardNavRepository.Table
    .OrderBy(x => x.Id)
    .Select(x => new MLS_DashboardNavigation()
    {
        Id = x.Id,
        Name = x.Name,
        Description = x.Description,
        ImageUrl = x.ImageUrl,
        SubDashNav = x.SubDashNav
    }).ToList();

如果MLS_DashboardNavigation与_mlsDashboardNavRepository的类型相同。您甚至不需要选择表格，因为这就是返回的内容。

var query = _mlsDashboardNavRepository.Table
    .OrderBy(x => x.Id).ToList()
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