如何过滤相关的儿童记录 [英] How do I filter related Child Record

问题描述

我正在使用RIA服务。我需要选择一个有多个相关子实体（ UnitOccupierDetails ）的父实体（ UnitOccupier ）。我需要过滤子实体以返回单个记录。如何做到这一点？

  var q =从uo在_unitOccupierContext.GetUnitOccupierQuery（）
其中uo.UnitOccupierDetails。 ???? 
 --->我不能得到这里的子属性
  

谢谢

解决方案

您不能包含所选父项的过滤子集。您只能包含完整的集合或根本没有子集合。但是，作为一种解决方法，您可以使用中间匿名类型，如下所示：

  var q =（来自uo in _unitOccupierContext.GetUnitOccupierQuery ）
选择新的{
 Parent = uo，
 Childs = uo.UnitOccupierDetails 
 .Where（uod => uod.MyDetailsProp == MyDetailsValue）
}）。 FirstOrDefault（）; 
 
 if（q！= null）
 {
 UnitOccupier selectedUnitOccupier = q.Parent; 
 selectedUnitOccupier.UnitOccupierDetails = q.Childs.ToList（）; 
 // selectedUnitOccupier现在只包含被过滤的孩子
} 
  

编辑

如果你想查询孩子并包含他们的父母（与评论中的问题相关），你可以使用：

  var q = _unitOccupierContext.GetUnitOccupierQuery（）
 .SelectMany（uo => uo.UnitOccupierDetails 
 .Where（uod => uod.MyDetailsProp == MyDetailsValue））
 .Include（uod => uod.UnitOccupier）
 .FirstOrDefault（）; //或.ToList（），如果您期望多个记录
 // q现在为空或单个UnitOccupierDetails实体
 //引用其父
  

我假设你的 UnitOccupierDetails 类有一个导航属性到父 UnitOccupier 。

I am using RIA services. I need to select a parent entity (UnitOccupier) which has a number of related child entities(UnitOccupierDetails). I need to filter the child entities to return a single record. How do I do this?

var q = from uo in _unitOccupierContext.GetUnitOccupierQuery()
        where uo.UnitOccupierDetails.????
                                     ---> I cant get to the child properties here

Thanks

解决方案

You cannot include a filtered child collection of the selected parent. You can only include either the full collection or no child collection at all. But as a workaround you could use an intermediate anonymous type, like so:

var q = (from uo in _unitOccupierContext.GetUnitOccupierQuery() 
         select new {
             Parent = uo,
             Childs = uo.UnitOccupierDetails
                        .Where(uod => uod.MyDetailsProp == MyDetailsValue)
         }).FirstOrDefault();

if (q != null)
{
    UnitOccupier selectedUnitOccupier = q.Parent;
    selectedUnitOccupier.UnitOccupierDetails = q.Childs.ToList();
    // selectedUnitOccupier now only contains the filtered childs
}

Edit

If you want to query for the childs and include their parents (related to question in comment) you could use:

var q = _unitOccupierContext.GetUnitOccupierQuery()
         .SelectMany(uo => uo.UnitOccupierDetails
                             .Where(uod => uod.MyDetailsProp == MyDetailsValue))
         .Include(uod => uod.UnitOccupier)
         .FirstOrDefault(); // or .ToList() if you expect more than one record
// q is now null or a single UnitOccupierDetails entity
// with a reference to its parent

I am assuming here that your UnitOccupierDetails class has a navigation property to the parent UnitOccupier.

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