MVC .Net view nested list of models

Question

I have an abstract class with 3 other classes that inherit from this class:-

public abstract class AbstractTask
{
  [Key]
  public int ID {get; set;}
  [DisplayName("Featured Task")]
  public bool Featured { get; set; }
  // various other properties
}

public class HighLevelTask : AbstractTask
{
  [DisplayName("Workstream Description")]
  public String Workstream { get; set; }
  public virtual ICollection<MidLevelTask> MidLevelTasks { get; set; }
}

public class MediumLevelTask : AbstractTask
{
  public int HighLevelTaskID { get; set; }
  public virtual ICollection<DetailLevelTask> DetailLevelTasks { get; set; }
}

public class DetailLevelTask : AbstractTask
{
 public int MidLevelTaskID { get; set; }
}

So a High Level task can contain any number of Mid Level tasks and a Mid level task can contain any number of Detail tasks. Tasks at any level can be set as 'Featured' by the property inherited from the abstract class.

In a HTML view I want to present a nested list of the 'featured' tasks. So I am thinking in a Controller action something like this to collect all the featured tasks but am at a mental block on the best way to present this.

  var qryHighLevelTasks = from t in context.HighLevelTasks
                          where t.Featured == true
                          select t;
  var rsHighLevelTasks = qryHighLevelTasks.ToList();

  foreach(var highLevelTask in rsHighLevelTasks)
  {
     // get all mid level featured tasks related to this high level task
     var qryMidTasks = from midLevelTasks in context.MidLevelTasks
                       where midLevelTasks.Featured == true
                       && midLevelTasks.HighLevelTaskID == highLevelTask.ID
                       select midLevelTasks;
     var rsMidLevelTasks = qryMidTasks.ToList();

     foreach (var midLevelTask in rsMidLevelTasks)
     {
        // get all detail level featured tasks related to this mid level task
        var qryDetailTasks = from detailLevelTasks in context.DetailLevelTasks
                             where detailLevelTasks.Featured == true
                             && detailLevelTasks.MidLevelTaskID == midLevelTask.ID
                             select detailLevelTasks;
        var rsDetailLevelTasks = qryDetailTasks.ToList();                    
        }                
   }

Perhaps I should have a composite model to represent the featured tasks? Or is there a better way? Any recommendations?

I would create a viewmodel, more code, but far more readable — Steve B
– Steve B, Commented Jun 13, 2012 at 7:21
It would be better to consider a 'Partial View' to render the nested list of the 'featured tasks'. In addition, try to focus on your view-model first. You may have a collection of 'featured tasks' in your view-model, and pass these collection to your partial view to be rendered. — Yusubov
– Yusubov, Commented Jun 13, 2012 at 11:56

Yusubov · Accepted Answer · 2012-06-13 19:29:09Z

2

I would suggest the 'Partial View' to render the nested list of the 'featured tasks'.

In addition, try to focus on your view-model first. You may have a collection of 'featured tasks' in your view-model, and pass these collection to your partial view to be rendered. Here you some links that might help:

1) Partial Views and Strongly Typed Custom ViewModels

2) How Do I: Work with Data in ASP.NET MVC Partial Views?

edited Jun 13, 2012 at 19:29

answered Jun 13, 2012 at 12:05

Yusubov

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1 Comment

Yusubov Over a year ago

@Gordon, any feedback on my answer ?

user965160 · Accepted Answer · 2012-06-13 15:08:03Z

You can use LINQ projection to retrieve nested items:

var featuredItems = from hl in context.HighLevelTasks where hl.Featured == true
                    select new
{
   MidLevelTasks = from md in context.MidLevelTask where md.MidLevelTaskID = h1.TaskID,
   DetailLevelTasks = from ll in context.DetailLevelTask where ll.LowLevelTaskID = md.MidLevelTaskID
};

You can also use Editor Templates to render the nested Views:

Main view :

foreach(item in Model.HighLevelTasks)
{
   @Html.EditorFor(item);  
}

HighLevelTask View:

<!-- HTML here to render the parent record -->
foreach(item in Model.MidLevelTasks)
{
  @Html.EditorFor(item)
}

..in a similar pattern, create editor templates for Middle and Detail Level tasks.

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