When should I use ICollection or IEnumerable in viewModel?

Question

using IEnumerable

view model

public class ResumeDetailsViewModel
{
    public IEnumerable<WorkExperience> WorkExperiences { get; set; }
}

in controller

var workExperiences = _dbContext.WorkExperiences.Where(w => w.UserId == userId);
var viewModel = new ResumeDetailsViewModel
{
    WorkExperiences = workExperiences,
};

in view

@if (Model.WorkExperiences.Any())
{
    foreach (var workExperience in Model.WorkExperiences)
    {
        @workExperience.JobTitle
    }
}

using ICollection

view model

public class ResumeDetailsViewModel
{
    public ICollection<WorkExperience> WorkExperiences { get;set; }
}

in controller

var workExperiences = _dbContext.WorkExperiences.Where(w => w.UserId == userId);
var viewModel = new ResumeDetailsViewModel
{
    WorkExperiences = workExperiences.ToList()
};

in view

@if (Model.WorkExperiences.Any())
{
    foreach (var workExperience in Model.WorkExperiences)
    {
        @workExperience.JobTitle
    }
}

I want to have least query as possible. In my example both approach creates 2 queries Model.WorkExperiences.Any() and var workExperience in Model.WorkExperience for IEnumerable while workExperiences.ToList() and Model.WorkExperiences.Any() for ICollection.

Please correct me if I'm wrong with my assumption.

When should I use ICollection or IEnumerable?

ICollection does some things that IEnumerable doesn't. It has a `Count` property. It has Add, Remove, and Clear methods. If you need any of the features that ICollection has and IEnumerable doesn't, use ICollection. — 15ee8f99-57ff-4f92-890c-b56153, Mar 09 '17 at 16:09
ICollection inherits from IEnumerable and provides a few more methods and properties to allow for better access (rather than just looping through with an iterator). — Paul Gibson, Mar 09 '17 at 16:10
You don't need your call to `.Any()` - just do your foreach. — Dan Field, Mar 09 '17 at 16:10
@juharr `ICollection` doesn't have an indexer; that's `IList`. For example `HashSet` implements `ICollection`, but not `IList`. — 15ee8f99-57ff-4f92-890c-b56153, Mar 09 '17 at 16:11

When should I use ICollection or IEnumerable in viewModel?

0 Answers0