Show only if a ViewModel has value in MVC

Question

I have this class and many properties in it

    public class Course
    {
      public int CourseId { get; set; }
      public string CourseName { get; set; }
      public Universities? UniversityName { get; set;}
      public string Summary { get; set; }
      *
      *
    }

View Model looks like this

    public class DetailsViewModels
    {
      public Course DetailsVMCourse;
      public string PageTitle;
      *
    }

And controller

    public IActionResult CourseDetails(int id)
    {
        DetailsViewModels detailsViewModels = new DetailsViewModels()
        {
            //loads the course to the view model from a test database
            DetailsVMCourse = _courseRepository.FindCourse(id)
        };
        return View(detailsViewModels);
    }

I want to show only if a model property has value in the view. At the moment I am doing this on the view page for each property..

@{ if (Model.DetailsVMCourse.Summary != null)
  {
   <h4>Cource summary</h4>
   <p>
   @Model.DetailsVMCourse.Summary
   </p>
  }
}

Rather than checking every single property with !=null in view, what would be better and efficient way. This is my first project so your help would be greatly appriciated.

You would check it in the view as you are doing now. Or you can check it before you return from the action and can select a different view based on the model's result. — Jasen, Jan 28 '20 at 23:40

score 0 · Accepted Answer · answered Jan 28 '20 at 23:43

You could write something that would loop over every property in the class using reflection, but I'm thinking you really don't want that. The properties are of different types and I am sure there are some you may not actually want to show (IDs?). With some being other classes, it gets complicated (UniversityName is an object, not a string). Also, within your H4 Tag, the "title" is not the same as the property, it's more human-readable. So I think your best bet is to follow your current pattern and have a block for each property that you really want to show, along with its human-readable title.

My only other suggestion would be to use IsNullOrWhiteSpace() instead of the null check for the string properties. It's a cleaner/thorough check for strings:

if (!String.IsNullOrWhiteSpace(Model.DetailsVMCourse.Summary))

You are correct, dont want to use reflection, as my properties are different types. Thank you for your help. :) — aries, Jan 29 '20 at 00:24
@aries, no problem. If you feel this is an adequate answer, please mark this as the answer to close this question. — Bryan Lewis, Jan 29 '20 at 00:49

score 0 · Answer 2 · answered Jan 28 '20 at 23:44

0

I would use reflection to get the properties that have a value that is not equal to null, and then use a loop to display the properties and its values.

var populatedProperties = Model.DetailsVMCourse.GetType().GetProperties().Where(prop => prop.GetValue(Model.DetailsVMCourse) != null);

foreach (var prop in populatedProperties){
   <h4>@prop.Name</h4>
   <p>
   @prop.GetValue(Model.DetailsVMCourse);
   </p>
}

answered Jan 28 '20 at 23:44

Jossean Yamil

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2
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Although properties are different types, but I can use this in a different class. Thanks for the idea. – aries Jan 29 '20 at 00:28

Show only if a ViewModel has value in MVC

2 Answers2