CODEWITHSUNDEEP
asp.net-mvc-3linqasp.net-mvc-4
Murat Erdogan
Murat Erdogan

Reputation: 798

How to use Html.DropDownListFor() helper in the right way

I have a signup form. I want users can select their pet's race using a select list in html. So i decided to use Html.DropDownListFor() Html helper.

In my model:

public class PetModel
{
    public long id { get; set; }
    public short gender { get; set; }
    public short type { get; set; }
    public string name { get; set; }
    public int raceID { get; set; }
    public int birthYear { get; set; }
    public int weight { get; set; }
    public bool neutered { get; set; }

    public IEnumerable<SelectListItem> raceList { get; set; }
}

And i want to populate a drop down list for raceList that users can select their pet's race.

So i created a controller for a partial view

public PartialViewResult _SignupPet(PetModel model)
{
    model.raceList = entity.PetRaces.Select(w => new SelectListItem { Text = w.name, Value = w.id.ToString() });

    return PartialView(model);
}

And in my view:

@Html.DropDownListFor(m=>m.raceID, Model.raceList)

But i'm receiving this error.

LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression.

Now i'm wondering about this. I generally use drop down list to select an id and show user a text instead of ids. How will i use this Html.DropDownListFor() helper in my projects. Am i using a wrong approach?

Upvotes: 2

Views: 122

Answers (2)

Murat Erdogan
Murat Erdogan

Reputation: 798

I couldn't solve my original problem but i found an alternative solution. In my controller i changed the code

model.raceList = entity.PetRaces.Select(w => new SelectListItem { Text = w.name, Value = w.id.ToString() });

to

model.raceList = entity.PetRaces.Select(w => new SelectListItem { Text = w.name, Value = SqlFunctions.StringConvert((double)w.id).Trim() });

Upvotes: 1

Lotok
Lotok

Reputation: 4607

Your Unique ID for the SelectListItem needs to be a string. You cannot do a conversion in the LINQ as it won't translate. I have got around it by using the name as both text and Id as in my case it was unique.

Another example of this same question here: Linq int to string

Upvotes: 1

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