Disable a default value from dropdownlist

Alex P

Hi, I have a code where it takes and saves input as XYZ if no value is selected from a drop down list. I want to disable it, so that the system is not allowed to save any empty value.

As a trial & error method I just uncommented a piece of code.

//var defaultSelectItem = new SelectListItem() { Text = "-SELECT ONE-", Value = "XYZ", Selected = String.IsNullOrEmpty(jurisCode) };

//jurisForDisplay.Insert(0, defaultSelectItem);

Result: It doesn't give me a option to leave blank.

Partial problem: System itself gives a state name as a default input in alphabetic order. So, the user should be cautious to edit the state name. Which is tough in my case as end users are truck drivers.

Is there something else I can do which allows user to select input by himself and should also not allow a blank valur to be saved.

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

James Axsom8y ago
Alex, consider an alternative approach:

Possible State 1
State: No value selected from a drop down list
Result: No XYZ is saved

Possible State 2
State: A value is selected from a drop down list
Result: XYZ is saved

Goal: Disable ListBox so that system won't save an empty value.

Possible solution:
Go to your save subroutine and see how you are handling the ado.net sql parameter value. Just because you disable a list box doesn't mean that something like an empty string or a null value is not being saved.

If you don't want to save this value per a condition then test for it in your save sub routine.

If(there is value==true)
{
// add parameter to your sql command
}
// else don't add the parameter
Alex P8y ago
Thanks James for the quick response.

var newJuris = new JurisdictionMilesEntity();
newJuris.ObjectStatus = CVISNConstants.MARKED_FOR_INSERT;
newJuris.JurisdictionCode = "XYZ";
int maxId = (model.FuelType.JurisdictionMiles.Count() > 0) ? model.FuelType.JurisdictionMiles.Max(x => x.TempId) : 0;
newJuris.TempId = maxId + 1;

I think this is the code where it is taking the default value to be XYZ.

Is there a chance I can remove XYZ and not storig empty value xyz and pop a message to select one from existing list
James Axsom8y ago
Hi Alex,

Use this code block or something like it that evaluates conditions when the listbox should be disabled.
I hope this idea may provide you inspiration or ideas to assist you.
public bool SetListEnabled()
{
    bool result = false;

    // Conditions for true
    // 1) There must something selected in the listbox
    result = (ListBox.SelectedItems.Count>0)==true;

    return result;
}

public class Test
{
    public void Test()
    {
        // Test can be any event or method that triggers the need
        // to evaluate the List's boxes enabled state
        ListBox.Enabled = SetListEnabled();
    }
}