MVC3 Linq選擇每個類別的前5名

Question

我想在局部視圖中選擇和顯示每個新聞類別的最近5個提交。新聞表具有類別Id作爲外鍵。我有下面的代碼，但它在測試中什麼也沒有顯示。任何人都可以協助

守則新聞控制器

public ActionResult _HomeCatNews() 
{ 
    var info = db.News 
     .GroupBy(r => r.CatId) 
     .SelectMany(g => g.OrderBy(r => r.RevDate) 
     .Take(5)) 
     .ToList(); 
    return PartialView(); 
} 

局部視圖視圖代碼如下

@model IEnumerable<KPortal.Models.HomeNewzCat> 
@using KPortal.Helpers 

@foreach (var item in Model) {   
    <ul> 
     <li> 
      <div class="image"> 
       <a href="#">@Html.DisplayFor(modelItem => item.NewsPic)</a> 
      </div> 
      <div class="details"> 
       <h5><a href="#">@Html.Raw(Html.Truncate(item.NewsContent, 55, ""))</a></h5> 
       <span class="date"> 
        @Html.DisplayFor(modelItem => item.RevisionDate) 
        @Html.DisplayFor(modelItem => item.NewSource) 
       </span> 
      </div> 
      @Html.DisplayFor(modelItem => item.NewsTitle) 
     </li>       
    </ul> 
} 

HomeNewzCat型號

namespace KPortal.Models 
{ 
    public class HomeNewzCat 
    { 
     [Display(Name = "Category ID")] 
     public int CategoryID { get; set; } 

     [Display(Name = "Category")] 
     public string Category { get; set; } 

     [Display(Name = "Revision Date")] 
     public DateTime RevisionDate { get; set; } 

     [Display(Name = "News Title")] 
     public string NewsTitle { get; set; } 

     [Display(Name = "Story Picture")] 
     public string NewsPic { get; set; } 

     [AllowHtml] 
     [Display(Name = "News Content")] 
     public string NewsContent { get; set; } 

     [Display(Name = "Source")] 
     public string NewSource { get; set; } 

     public DateTime Date { get; set; } 
    }  
} 

Answer 1

首先，移動foreach循環之外你<ul>標籤並且添加一個檢查是否沒有記錄返回

@if(Model != null) { 
    <ul> 
     @foreach(var item in Model) { 
      <li> 
       <div class="image"> 
        <a href="#">@Html.DisplayFor(modelItem => item.NewsPic)</a> 
       </div> 
       <div class="details"> 
        <h5><a href="#">@Html.Raw(Html.Truncate(item.NewsContent, 55, ""))</a></h5> 
        <span class="date"> 
         @Html.DisplayFor(modelItem => item.RevisionDate) 
         @Html.DisplayFor(modelItem => item.NewSource) 
        </span> 
       </div> 
       @Html.DisplayFor(modelItem => item.NewsTitle) 
      </li> 
     } 
    </ul> 
} 

接下來，我們需要建立的HomeNewzCat列表發送到局部視圖

public ActionResult _HomeCatNews() 
{ 
    var info = db.News 
     .GroupBy(r => r.CatId) 
     .SelectMany(g => g.OrderBy(r => r.RevDate) 
     .Take(5)) 
     .ToList(); 

    var model = new List<HomeNewzCat>(); 
    HomeNewzCat record = null; 

    // first make sure we have some records 
    if(info.Count() > 0) { 
     foreach(var item in info) { 
      // you will need to modify these item.Field to match your database names 
      record = new HomeNewzCat 
         { 
          CategoryID = item.CatID, 
          Category = item.Category, 
          RevisionDate = item.RevDate, 
          NewsTitle = item.NewsTitle, 
          NewsPic = item.NewsPic, 
          NewsContent = item.NewsContent, 
          NewsSource = item.NewsSource, 
          Date = item.Date 
         }; 
      model.Add(record); 
     } 
    } 
    return PartialView("_HomeCatNewz", model); 
}