Question

我有以下2个列表

- `List<Category>`
- `List<SubCategory>`

        public class Category
        {
            public string CategoryId 
           {
               get;
               set;
           }

           public List<SubCategory> subCategories
           {
               get;
               set;
           }


    public string Name
{
get;
set;
}
        }


        public class SubCategory
        {
             public string SubCategoryId
             {
                 get;
                 set;
             }
            public string CategoryId 
            {
                 get;
                 set;
            }
            public string Name
            {
                 get;
                 set;
            }
         }

我想在类别和子类别中找到匹配的类别（按CategoryId）。
将具有特定CategoryId的所有子类别添加到Category的subCategories数组中，并使用相同的CategoryId CategoryId。

到目前为止，我已经尝试过了。

var categories = Categories.Select(c => c.Id);

            foreach(Guid categoryId in categories)
            {
                var subCategoriesByCategoryId = validatedSubCategories.Where(subCats => subCats.CategoryId == categoryId);
                List<SubCategory> subCategories = new List<SubCategory>();
                foreach(SubCategory subCategory in subCategoriesByCategoryId)
                {
                    subCategories.Add(subCategory);
                }

                if (subCategories.Count() > 0)
                {
var categoryById = Categories.FirstOrDefault(vC => vC.Id == categoryId);
if (categoryById != null) categoryById.SubCategories = subCategories;
                }
            }

我如何实现这一目标？

样本数据

Category cat1= new Category {CategoryId=1};
Category cat2= new Category {CategoryId=2};
Category cat3= new Category {CategoryId=3};
Category cat4= new Category {CategoryId=4};

List<Category > Categories = new List<Category >()
Categories.Add(cat1);
Categories.Add(cat2);
Categories.Add(cat3);
Categories.Add(cat4);

SubCategory sc1 = new SubCategory {CategoryId=1);
SubCategory sc2 = new SubCategory{CategoryId=2};
SubCategory sc3 = new SubCategory{CategoryId=3};
SubCategory sc4 = new SubCategory{CategoryId=4};

List<SubCategory> SubCategories = new List<SubCategory >()
SubCategories.Add(sc1);
SubCategories.Add(sc1);
SubCategories.Add(sc3);
SubCategories.Add(sc4);

预期outPut

2具有CategoryId 1的子类别中的子类别项目应添加到CategoryList中具有CategoryId 1的类别项目

1具有CategoryId 3的子类别中的子类别项目应添加到CategoryList中具有CategoryId 3的类别项目

1具有CategoryId 4的子类别中的子类别项目应添加到CategoryList中具有CategoryId 4的类别项目

Answer 1

请尝试以下声明：

List<Category> categories = new List<Category>();
List<SubCategory> subCategories = new List<SubCategory>();

var matchingCategories = from mt in categories
    join sub in subCategories
        on mt.CategoryId equals sub.CategoryId
    group sub by new { mt.CategoryId, mt.Name}
    into grp
    select new Category() {CategoryId = grp.Key.CategoryId , Name = grp.Key.Name, subCategories = grp.ToList()};

var result = matchingCategories.ToList();

两个列表类别和子类别

1 个答案: