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我在 RavenDB 的单个文档中保存了一个类别层次结构。

"CategoryList": [
{
  "$id": "1",
  "Id": "Admin",
  "Name": "Administration",
  "ParentCategory": null,
  "Subcategories": [
    {
      "$id": "2",
      "Id": "Admin1",
      "Name": "Administration 1",
      "ParentCategory": {
        "$ref": "1"
      },
      "Subcategories": []
    },...

我可以使用这两个类在 C# 中成功加载它

public class Categories
{
    public string Id { get; set; }
    public IEnumerable<Category> CategoryList{ get; set; }
}

[JsonObject(IsReference = true)]
public class Category
{
    private readonly IList<Category> _subcategories;

    public string Id { get; set; }
    public string Name { get; set; }
    public Category ParentCategory { get; set; }

    public IEnumerable<Category> Subcategories
    {
        get { return _subcategories; }
    }

    public Category()
    {
        _subcategories = new List<Category>();
    }

    public void AddSubcategory(Category subcategory)
    {
        subcategory.ParentCategory = this;
        _subcategories.Add(subcategory);
    }
}

但现在我想查询我的类别层次结构以通过其 Id 检索单个类别。我怎么能那样做？每个类别创建一个文档会更好吗？

谢谢

更新：

嗨，艾扬德，

谢谢回复。我相信Hierarchy您文章中使用的方法已经过时，但我能够找到新版本......

阅读本文后，我创建了一个返回所有类别的索引：

public class CategoriesByIdIndex : AbstractIndexCreationTask<Categories, CategoriesByIdIndex.ReduceResult>
{
    public class ReduceResult
    {
        public string Id { get; set; }
        public Category Category { get; set; }
    }

    public CategoriesByIdIndex()
    {
        Map = categoriesCollection => from categories in categoriesCollection
                                      from category in categories.CategoryList
                                      from subcategory in category.Hierarchy(x => x.Subcategories)
                                      select new
                                                 {
                                                     subcategory.Id,
                                                     Category = subcategory
                                                 };

        Store(x => x.Id, FieldStorage.Yes);
        Store(x => x.Category, FieldStorage.Yes);
    }
}

当我执行此查询时，将返回所有类别：

var allCategories = session.Query<Categories, CategoriesByIdIndex>()
            .AsProjection<CategoriesByIdIndex.ReduceResult>()
            .ToList();

但是当我尝试按类别 ID 过滤它时，我收到一个空列表：

var singleCategory = session.Query<Categories, CategoriesByIdIndex>()
            .AsProjection<CategoriesByIdIndex.ReduceResult>()
            .Where(x => x.Id == "Admin1")
            .ToList();

我究竟做错了什么？

谢谢

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