How to Create an Empty SelectList

Question

I have the folloiwng action method:

public JsonResult LoadSitesByCustomerName(string customername)
{
    var customerlist = repository.GetSDOrg(customername)
                                 .OrderBy(a => a.NAME)
                                 .ToList();
    var CustomerData;
    CustomerData = customerlist.Select(m => new SelectListItem()
    {
        Text = m.NAME,
        Value = m.NAME.ToString(),
    });
    return Json(CustomerData, JsonRequestBehavior.AllowGet);
}

but currently i got the following error on var CustomerData;:

implicitly typed local variables must be initialized

so i am not sure how i can create an empty SelectList to assign it to the var variable ? Thanks

Solution 1

You could try this one:

IEnumerable<SelectListItem> customerList = new List<SelectListItem>();

The error you were getting is reasonable, since

The var keyword instructs the compiler to infer the type of the variable from the expression on the right side of the initialization statement.

On the other hand, you could try the following one:

var customerList = customerlist.Select(m => new SelectListItem()
                   {
                       Text = m.NAME,
                       Value = m.NAME.ToString(),
                   });

The reason why the second assignment will work is that in this way the compiler can infer the type of the variable, since it knows the type of the LINQ query returns.

Solution 2

Use this to create an empty SelectList:

new SelectList(Enumerable.Empty<SelectListItem>())

Enumerable.Empty<SelectListItem>() creates an empty sequences which will be passed to the constructor of SelectList. This is neccessary because SelectList has no constructor overloading without parameters.

Solution 3

Try this:

customerlist = new[] { new SelectListItem { } };

Solution 4

That error means that you cannot declare a var variable without giving a value, for example:

var double1 = 0.0; // Correct, compiler know what type double1 is.
var double2; // Error, compiler not know what type double2 is.

You need to assign a value to var CustomerData; for example:

var CustomerData = customerlist.Select(m => new SelectListItem()
            {
                Text = m.NAME,
                Value = m.NAME.ToString(),

            });

Solution 5

Initialise the variable when you declare it:

var CustomerData = customerlist.Select(m => new SelectListItem()
{
    Text = m.NAME,
    Value = m.NAME.ToString(),
});

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Comments

[Mardoxx]

How can you create an instance of an interface?

[Christos]

@Mardoxx oops...I just noted it and I corrected it.