使用LINQ取得子类别中的所有项目 [英] Take all items in sub-categories using LINQ

问题描述

我想获取当前类别中的所有项目以及链接到当前项目的所有子类别.当前，我使用递归函数，但是我怀疑可以通过修改查询来完成.主要原因是我想使用.Skip()和.Take()，但是如果我仍然必须先使用递归来获取所有类别，这不会有任何区别.

I want to take all items in current category and all sub categories that are linked to current one. Currently I do so using recursive function, but I suspect that it can be done just by modifying query. Main reason is that I want to use .Skip() and .Take() but it won't make any difference if I still have to take all categories first using recursion.

public static IQueryable<Models.Item> Items(int id, List<Models.Item> items)
{
    if (items == null)
    {
        items = new List<Item>();
    }

    ModelDataContext _db = new ModelDataContext();

    var currentCategory = _db.Categories.Where(x => x.ID == id).Single();

    items.AddRange(currentCategory.Items);

    foreach (var c in currentCategory.Categories)
    {
        Items(c.ID, items);
    }

    return items.AsQueryable();
}

tl; dr;
具有递归功能，可获取类别和子类别中的所有项目.怀疑仅凭LINQ本身是否有可能.

tl;dr;
Have recursive function that gets all items in category and sub-categories. Wonder if it's possible just by LINQ itself.

推荐答案

EF或LINQ to SQL都不支持急于加载自引用对象.如果他们支持新的HeirarchyID，则有可能，但是，but，这两个平台都没有对此的真正支持.

Neither EF or LINQ to SQL support eager loading of self-referencing objects. It could be possible if they supported the new HeirarchyID, but alas, neither platform has real support for that at this point either.

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