如何在asp.net的新闻中获取类别计数使用

Posted 2023-04-01

【中文标题】如何在asp.net的新闻中获取类别计数使用

【英文标题】：How to get Category Count Use at News in asp.net

【发布时间】：2021-10-03 21:35:43

【问题描述】：

大家好，我在获取新闻中使用的类别计数时遇到问题

例如我想知道“国际”类别在新闻中有多少使用

这是我的新闻实体：

 public class News
    
        public int NewsId  get; set; 
       
        public int? SubGroup  get; set; 

        public string NewsTitle  get; set; 
        public string NewsBody  get; set; 
        public DateTime CreatedDate  get; set; 
        public string Poster  get; set; 
       
        public DateTime? UpdateTime  get; set; 
        public bool  isChoseClerck get; set; 

        public News()
        
            this.CreatedDate = DateTime.Now;
        

        //RelationShip
        public List<Category>  Category  get; set; 
        public User User  get; set; 
        public List<Tag> Tags  get; set; 
        public string Source get; set; 
    

这是我想向用户展示的 Dto：

 public class SubCategoryWithCountDTO
    
        public int CategoryId  get; set; 
        public string CateGoryName  get; set; 
        public int UseCount  get; set; 
    

我在下面写了服务但我不知道我不能在“包含”中使用 lambda

 public async Task<List<SubCategoryWithCountDTO>> SubCategoryWithCount(int skip, int take)
        
            var subCategoryList = await _context.Categories
                .Where(x => x.ParentId != null).OrderBy(x => x.CategoryId)
                .Skip(skip).Take(take).ToListAsync();
            var SubCategoryWithCount = new List<SubCategoryWithCountDTO>();
            foreach (var item in subCategoryList)
            
                var categoryUse = _context.News.Include(x => x.Category
                    .Select(x => x.CategoryId == item.CategoryId)).Count();
                var preSubCategory = new SubCategoryWithCountDTO
                
                    CategoryId = item.CategoryId,
                    CateGoryName = item.CateGoryName,
                    UseCount = categoryUse
                ;
                SubCategoryWithCount.Add(preSubCategory);
            

            return SubCategoryWithCount;
        

谁能告诉我正确的方法？，谢谢

【问题讨论】：

你能分享一个示例结果和你的对象列表吗？

【参考方案1】：

您可以通过这种方式实现您的目标：

public List<TagWithUseCountViewModel> GetTagWithCount()
    

        var list = new List<TagWithUseCountViewModel>();

        var query = from item in _context.News.SelectMany(x => x.Tags)
                    select item;

        foreach (var item in query)
        
            list.Add(new TagWithUseCountViewModel
            

                Id = item.Id,
                TagName = item.TagName,
                UseCount =
                query.Where(x => x.Id == item.Id).GroupBy(x => x.NewsList).Count()
            );