CODEWITHSUNDEEP
c#
user2382644
user2382644

Reputation: 17

Getting comboBox value for parameters

For my project I'm using a library and it has a list of pre-defined options. I want to be able to choose from a comboBox so I don't need to edit the source everytime.

main code: Searches for a player. Level can either be set as Gold, Silver, Bronze or All. I want to be able to choose that from comboBox. The error at the end shows when I click a button to run this code.

var searchRequest = new SearchRequest();
var searchParameters = new PlayerSearchParameters
{
    Page = 1,
    Level = comboBox1.SelectedItem == null ? Level.All : (Level)(comboBox1.SelectedItem as ComboboxItem).Value,
    //usually set like this Level - Level.Gold,
};

comboBox code:

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    foreach (Level level in Enum.GetValues(typeof(Level)))
    {
        ComboboxItem item = new ComboboxItem();
        item.Text = level.ToString();
        item.Value = level;
        comboBox1.Items.Add(item);
    }
}

ComboboxItem code:

public class ComboboxItem
{
    public string Text { get; set; }
    public object Value { get; set; }

    public override string ToString()
    {
        return Text;
    }
}

I thought that all of this would work but it give an error saying NullReferenchExeption was unhanded by user code. and Object reference not set to an instance of an object.

I really need help with getting this to work.

All help is really appreciated.

Thanks,

Jack.

Upvotes: 1

Views: 1345

Answers (2)

Damith
Damith

Reputation: 63065

you can bind the comboBox1 directly from enum as below 

comboBox1.DataSource  =Enum.GetNames(typeof(Level));

then if you need to get selected enum 

Level level ; 
if( Enum.TryParse<Level>(comboBox1.SelectedValue.ToString(), out level))
{ 
        var searchParameters = new PlayerSearchParameters
        {
            Page = 1,
            Level =level 
        };
}

Upvotes: 1

Derek W
Derek W

Reputation: 10026

After running what you have posted here - the only time that I receive a NullReferenchExeption is when I click the search button when nothing has been selected in the Combobox yet.

You need to check for null first. Like so...

if (comboBox1.SelectedItem != null)
{
     var searchRequest = new SearchRequest();
     var searchParameters = new PlayerSearchParameters
     {
          Page = 1,
          Level = (Level)(comboBox1.SelectedItem as ComboboxItem).Value,
          //usually set like this Level - Level.Gold,
     };
}

Upvotes: 0

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