从两个集合创建父级 -> 子级层次结构

Question

我有两个单独的集合实例，其中填充了数据

List<Parent> parents;
List<Child> children;

通过 Child.ParentId 和 Parent.Children 可以连接两个集合。

parents 集合没有填充 Children 属性，那么如何将 Parent 对象与 Children 链接？

Answer 1

试试这个：

var result = from d in parents  
             join s in children  
             on d.ParentID equals s.ParentID into g  
             select new  
             {  
                 ParentName = d.ParentName,  
                 ChildList = g  
             };

foreach (var item in result)  
{  
    Console.WriteLine("Parent: {0}", item.ParentName);  
    foreach (var Child in item.ChildList)  
    {  
        Console.WriteLine(Child.Name);  
    }  
    Console.WriteLine();  
}

Answer 2

 children.Join(parents,
                c => c.ParentId,
                p => p.ParentId,
                (c, p) => new { children = c, parents = p })
                .Select(x => x.parents).ToList();

更新

var result = parents.Join(children,
                     p => p.ParentId,
                     c => c.ParentId,
                     (p,c) => new { parents = p,children = c  })
                     .Select(x => new
                     {
                         ParentName = x.parents.ParentName,  
                         ChildList= x.children
                     })
                     //.GroupBy(x=>x.ParentName )
                     .ToList();