Question

In winform application, binding the Listbox with Dictionary via BindingSource property.

How do I get this BindingSource back to original Dictionary by type casting?

Eg:

Dictionary<string, string> objDic = getData();
OrderedDictionry ord = GetOrderedDict(objDic)
listBox.DataSource = new BindingSource(ord , null);
listBox.DisplayMember = "Value";
listBox.ValueMember = "Key";

Now, I want same Dictionary type value from listBox.DataSource for Linq query!!.

Eg:

var r = from t in (listBox.DataSource as Dictionary<string, string>).AsEnumaerable()
        select t;

throws error?

How to type cast to dictionary ?

Answer 1

You’re trying to cast a BindingSource to a Dictionary. You need to cast the BindingSource’s DataSource.

I don’t think you can cast from OrderedDictionary to Dictionary<>, but it would be easy to just reconstruct the Dictionary<string, string>:

    BindingSource bs = (BindingSource)listBox1.DataSource;
    OrderedDictionary ord = (OrderedDictionary)bs.DataSource;
    Dictionary<string, string> dict = new Dictionary<string, string>();

    foreach (DictionaryEntry item in ord)
        dict.Add(item.Key.ToString(), item.Value.ToString());

If you want a LINQ version, you could do:

   BindingSource bs = (BindingSource)listBox1.DataSource;
   OrderedDictionary ord = (OrderedDictionary)bs.DataSource;        

   var dict = ord.Cast<DictionaryEntry>().ToDictionary(d => d.Key, d => d.Value);