Key-Value Functionality in Combo Box

Combo box control is a control which displays a list of items. It combines the features of a text box and a list box. For the item which is selected in the combo box, we can get the selected index, which is in order of 0, 1, 2..

Today, we will learn how we can assign a key value pair to a combo box. The value will be shown to the end user and on the basis of the value, you can get the key.

E.g.: Consider the following key, value pairs:

Key: 1, Value: Rohit
Key: 2, Value: Suraj

Now, the combo box will show the values to the end user as Rohit, Suraj and for the selected item, you can get the key as either 1 or 2.

It is a simple three step procedure and am explaining it with some code samples.

Step 1: Create a new public class, say, KeyValuePair as

   public class KeyValuePair
   {
       public object m_objKey;
       public string m_strValue;
      
       public KeyValuePair(object NewKey,string NewValue)  
       {
           m_objKey = NewKey;
           m_strValue = NewValue;
       }  
      
       public override string ToString()  
       {
           return m_strValue;
       }       
   }

Step 2: From your Main class, add the items to combo box as

      comboBox1.Items.Add(new KeyValuePair("1", "Rohit"));
     comboBox1.Items.Add(new KeyValuePair("2", "Suraj"));
     comboBox1.Items.Add(new KeyValuePair("3", "Sandeep"));
     comboBox1.Items.Add(new KeyValuePair("4", "Jagdeep"));
     comboBox1.SelectedIndex = 0;

Step 3: Now you can fetch the key-value pair as

          KeyValuePair objKeyValuePair = (KeyValuePair)comboBox1.SelectedItem;
         string strkey = objKeyValuePair.m_objKey.ToString();
         string strvalue = objKeyValuePair.m_strValue.ToString();
         MessageBox.Show("Key: " + strkey + " || Value: " + strvalue);

That’s it. Put the code written in step 3 on some button click event, say button1Click_event. Now, whenever you will click the button, a message box will come that show you the Key and Value of the item which is currenlt selected in the combo box.

If you find any kind of issue/query, please do let me know.


Haapy coding
-Rohit