有条件的急切加载？ [英] Conditional eager loading?

问题描述

我想加载一个实体，它是有条件的孩子（我只想在child.IsActive == true时加载孩子）。如何执行以下操作？

I want to load an entity and it's children conditionally (I only want to eager load the children when the child.IsActive == true). How do I perform the following?

var parent = 
    from p in db.tblParents.Include("tblChildren") <-- where tblChildren.IsActive == true
    where p.PrimaryKey == 1
    select p;

注意：我不想返回匿名类型。

NOTE: I do not want to return an anonymous type.

谢谢。

推荐答案

这样做的一个方法是：

var parent = from p in db.tblParents where p.PrimaryKey == 1
             select new {
                 Parent = p,
                 Children = p.tblChildren.Where(c => c.IsActive == true)
             }.ToList();

但是，您可能不喜欢返回匿名类型的想法，那么我建议以这种方式编码：

However, you might not like the idea to return an anonymous type, then I would suggest to code it this way:

var parent = (from p in db.tblParents where p.PrimaryKey == 1).Single();
var childrens = ctx.Contacts.Where(c => c.ParentID == 1 && c.IsActive == true);
foreach (var child in childrens) {
   parent.tblChildren.Add(child);
}

这篇关于有条件的急切加载？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！