Question

给出以下代码，其中显示了包含300多个字段的模型中的字段列表：

Foo = await
    (
      _context.Foo
        .Where(r => !StatusExceptionList.Contains(r.Status))
        .Where(r => (Convert.ToDateTime(r.date) - today).TotalDays < 31)
        .Where(r => r.Pid == PId)                   
    )
    .Union
    (
    _context.Foo
        .Where(r => !DraftStatusExceptionList.Contains(r.Status))
        .Where(r => r.Pid == PId)
        .Where(r => r.Csstatus != "NA" || !String.IsNullOrEmpty(r.Csstatus))
        .Where(r => !_context.Foo
                    .Where(rr => rr.Pid == PersonId)
                    .Select(rr => rr.Fooid)                 
                    .Contains(r.Fooid)
              )
    )
    .ToListAsync();

是否可以将一个静态值为0的虚拟字段添加到union的一侧的记录中，将值1添加到union的另一侧的记录中，然后最后按虚拟字段排序内容？

这个想法是联盟的顶部先按顺序显示，然后在那之下，显示联合的第二部分。

以下示例是我在脑海中看到它并且它不起作用的方式，但是使用anon类型，但是使用*来从模型中抓取所有字段 -

Foo = await
    (
      _context.Foo
        .Where(r => !StatusExceptionList.Contains(r.Status))
        .Where(r => (Convert.ToDateTime(r.date) - today).TotalDays < 31)
        .Where(r => r.Pid == PId)                   
        .Select(rr => new
           {
               * //all fields that exist in r already need to be represented as well as the virtual field 'sortvalue'.....
               SortValue = 0
           });
    )
    .Union
    (
    _context.Foo
        .Where(r => !DraftStatusExceptionList.Contains(r.Status))
        .Where(r => r.Pid == PId)
        .Where(r => r.Csstatus != "NA" || !String.IsNullOrEmpty(r.Csstatus))
        .Where(r => !_context.Foo
                    .Where(rr => rr.Pid == PersonId)
                    .Select(rr => rr.Fooid)                 
                    .Contains(r.Fooid)
              )
        .Select(rrr => new
           {
               * //all fields that exist in r/rr already need to be represented as well as the virtual field 'sortvalue'.....
               SortValue = 1
           });
    )
    //...insert ordering logic here that uses sortValue to show the top query contents first, followed by the bottom queries contents
    .OrderBy(r => sortValue);
    .ToListAsync();

谢谢！

Answer 1

这是使用northwind db的示例。匿名类型用于跟踪结果来自哪个联合部分。然后使用鉴别器o对结果进行排序，然后使用select将其转换回原始类型。

var users = db.Employees
    .Where(emp => emp.FirstName == "Nancy")
    .Select(emp => new { emp, o = 0 })
    .Union( db.Employees
        .Where(emp => emp.City == "Seattle")
        .Select(u => new { emp, o = 1 })
        )
    .OrderBy(u => u.o)
    .Select(u => u.emp);

C＃Ef Core Linq查询在不使用模型

1 个答案: