實體框架查詢＃1

Question

我試圖找出如何限制我的孩子的數據集只包括主動記錄...

// Here's what I have currently... 
    m_BackLoggerEntities.Stories 
    .Include("Sprints") 
    .Include("Tasks") 
    .Include("Efforts") 
    .Include("Products") 
    .First(s => s.StoryId == id); 


    // Here's what I thought I could do... 
    m_BackLoggerEntities.Stories 
    .Include("Sprints") 
    .Include("Tasks") 
    .Include("Efforts") 
    .Include("Products") 
    .Where(s => s.Tasks.Active) 
    .First(s => s.StoryId == id); 


    // I also tried this... 
    m_BackLoggerEntities.Stories 
    .Include("Sprints") 
    .Include("Tasks") 
    .Include("Efforts") 
    .Include("Products") 
    .First(s => s.StoryId == id && s => s.Tasks.Active)); 

顯然都未工作。我不知道怎麼回事做到這一點...

Answer 1

看一看Alex James Tip 37。 據例如在鏈接的文章，這是可以做到這樣的：

var query = from story in m_BackLoggerEntities.Stories 
      where story.StoryId == id 
      select new { 
          story, 
          Tasks = from task in story.Tasks 
            where task.Active 
            select task 
         }; 

var stories = query 
    .AsEnumerable() 
    .Select(x => x.Story); 

每個故事裏面的「故事」的應該只有活動的任務。

Answer 2

我發現「模擬」我要的是要使用的唯一途徑...

 var storyToDetail = 
      m_BackLoggerEntities.Stories 
       .Include("Sprints") 
       .Include("Tasks") 
      .Include("Efforts") 
      .Include("Products") 
       .First(s => s.StoryId == id); 

然後在在foreach查看...

  <% foreach (var task in Model.Tasks.Where(t => t.Active)) 

但是，這當然帶來了更多的記錄，然後我想。

Answer 3

你需要的東西是這樣的：

Model = m_BackLoggerEntities.Stories 
    .Include("Sprints") 
    .Include("Tasks") 
    .Include("Efforts") 
    .Include("Products") 
    .SingleOrDefault(s => s.StoryId == id); 

然後，在你的看法：

@foreach (var task in Model.Tasks.Where(t => t.Active))