Ordering a linq list based on a property of a child class

Question

I have the following class:

public class CourseSection
{
    [Key]
    public int CourseSectionID { get; set; }

    public int CourseID { get; set; }

    public string Title { get; set; }

    public virtual ICollection<SectionContent> SectionContents { get; set; }
}

And the child class SectionContent is as shown here:

public class SectionContent
{
    [Key, Column(Order = 0)]
    public int CourseSectionID { get; set; }
    [ForeignKey("CourseSectionID")]
    public virtual CourseSection CourseSection { get; set; }

    [Key, Column(Order = 1)]
    public int ContentID { get; set; }
    [ForeignKey("ContentID ")]
    public virtual Content Content { get; set; }

    public int ContentOrder { get; set; }
}

I want to be able to sort the list of sectioncontent based on the ContentOrder field, I have the following data in my sectioncontent table:

CourseSectionID         ContentID         ContentOrder
1                       212               1
1                       208               2
1                       214               3
1                       210               4

But when displaying this in the view I have been unable to order the section contents based on the ContentOrder property. It is being displayed based on ContentID so it is showing as 208,210,212,214. How can I order the SectionContents based on this property? This is my razor view code:

foreach (var sectionItem in Model.CourseSections)
{                     
  <li>
    <h5 class="accordion-title">@sectionItem.Title<span class="accordion-icon"></span></h5>
      <div class="accordion-content">
        <ul>                                    
        @foreach (var subSectionItem in sectionItem.SectionContents)
        {
          <li><a href="#" id="menuItem @subSectionItem.ContentID @sectionItem.CourseSectionID" onclick="SubItemMenu(id)">@subSectionItem.Content.Name</a></li> 
        }
        </ul>
      </div>
  </li>
}              

Answer 1

The OrderBy extension method is what you're looking for.

@foreach (var subSectionItem in sectionItem.SectionContents.OrderBy(item => item.ContentOrder))
{
      <li><a href="#" id="menuItem @subSectionItem.ContentID @sectionItem.CourseSectionID" onclick="SubItemMenu(id)">@subSectionItem.Content.Name</a></li> 
}

Answer 2

Just add an OrderBy() statement to your foreach...

foreach (var sectionItem in Model.CourseSections)
{                     
  <li>
    <h5 class="accordion-title">@sectionItem.Title<span class="accordion-icon"></span></h5>
      <div class="accordion-content">
        <ul>                                    
        @foreach (var subSectionItem in sectionItem.SectionContents.OrderBy(sc => sc.ContentOrder))
        {
          <li><a href="#" id="menuItem @subSectionItem.ContentID @sectionItem.CourseSectionID" onclick="SubItemMenu(id)">@subSectionItem.Content.Name</a></li> 
        }
        </ul>
      </div>
  </li>
}

Alternatively you can do the OrderBy() when you fetch the data in the first place, and then assume that it's all in the right order in your view - the choice is yours.

Answer 3

I imagine you have some sort of service method returning your CourseSection model. In that method, set the sorted model property:

var myCourseModel = buildMyCourseSection();
myCourseModel.SectionContents = (from sc in myCourseModel.SectionContents 
    order by sc.ContentOrder
    select sc).ToArray();