CODEWITHSUNDEEP
c#asp.net-mvchtml.dropdownlistfor
Boris Parfenenkov
Boris Parfenenkov

Reputation: 3279

DropDownListFor doesn't select value when first element from collection

I have Model, which has following fields:

public List<SelectListItem> Months
{
    get
    {
        return new List<SelectListItem>
        {
            new SelectListItem {Text = "111", Value = "1"},
            new SelectListItem {Text = "222", Value = "2"}
        };
    }
} 
public List<TestModel> ServiceTest { get; set; }

Where TestModel has one field: 

public string Month { get; set; }

Model in view has ServiceTest = new List<ServiceTest> {new ServiceTest {Month = "2"}};

Now, question. Why this

@Html.DropDownListFor(m => m.ServiceTest[0].Month, Model.Months)

doesn't select second value. But this

@Html.DropDownListFor(m => m.ServiceTest[0].Month, new SelectList(Model.Months, "Value", "Text", Model.ServiceTest[0].Month))

work correct. I really don't understand why first expression doesn't work correctly.

Upvotes: 2

Views: 120

Answers (2)

Azhar Khorasany
Azhar Khorasany

Reputation: 2709

In order for the first statement to work, you need to provide the List by which it is bound.

Create a property in your class:

public string[] SelectedMonths { get; set; }

Then use:

@Html.DropDownListFor(m => m.SelectedMonths, new SelectList(Model.Monthes, "Value", "Text", Model.SelectedMonths))

Upvotes: 0

Darin Dimitrov
Darin Dimitrov

Reputation: 1038720

The reason for this is because the DropDownListFor helper supports only simple expressions when binding the default value. Things like x => x.SomeProp. In the first example you are using a complex lambda expression (Child property indexer access and yet another child property).

Your second approach is the correct way to solve this limitation of the helper.

Upvotes: 2

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