Question

我有以下查询要使用投影类名进行排序或过滤：

List<CompanyInfo> list = new List<CompanyInfo>();

using (var db = new DbContext())
{
    list.AddRange(
                  db.Companies.Include("Projects")
                  .Select(row => new CompanyInfo()
                  {
                      ProjectCount = (from s in row.Projects
                                      where s.Company.fId == row.fId
                                      select s.pId).Count(),
                      Id = satir.fId,
                  })
                 //.OrderBy("ProjectCount") //<== what I want to do
            );
}

我想使用与ProjectCount相同的Id或.OrderBy("ProjectCount")列来动态订购此查询，例如{{1}}。由于查询结果是IQueryable而不是ObjectContext，因此它不起作用。有没有办法做到这一点？

Answer 1

你应该能够这样做：.OrderBy(p => p.ProjectCount)

Answer 2

看一下Dynamic LINQ库这是tutorial，似乎描述了您的情况。

Answer 3

如果您知道该怎么做，可以使用LINQ做一些漂亮的事情。也许是这样的事情？

        var query = db.Companies.Include("Projects").Select(row => 
            new CompanyInfo() 
            { 
                ProjectCount = (from s in row.Projects where s.Company.fId == row.fId select s.pId).Count(), 
                Id = satir.fId, 
            });

        if (orderBy) // orderBy is bool, that tels you what to order by
            query = query.OrderBy(x => x.ProjectCount);
        else
            query = query.OrderBy(x => x.Id);

        list.AddRange(query);

Answer 4

感谢您的回复，我使用了帮助扩展方法：

Sorting in IQueryable using string as column name

动态排序和过滤预计的Entity SQL结果

4 个答案: