Binding Combobox Using Dictionary as the Datasource

问题

I'm using .NET 2.0 and I'm trying to bind a combobox's Datasource to a sorted dictionary.

So the error I'm getting is "DataMember property 'Key' cannot be found on the Datasource".

        SortedDictionary<string, int> userCache = UserCache.getSortedUserValueCache();
        userListComboBox.DataSource = new BindingSource(userCache, "Key"); //This line is causing the error
        userListComboBox.DisplayMember = "Key";
        userListComboBox.ValueMember = "Value";

回答1:

SortedDictionary<string, int> userCache = new SortedDictionary<string, int>
{
  {"a", 1},
  {"b", 2},
  {"c", 3}
};
comboBox1.DataSource = new BindingSource(userCache, null);
comboBox1.DisplayMember = "Key";
comboBox1.ValueMember = "Value";

But why are you setting the ValueMember to "Value", shouldn't it be bound to "Key" (and DisplayMember to "Value" as well)?

回答2:

I used Sorin Comanescu's solution, but hit a problem when trying to get the selected value. My combobox was a toolstrip combobox. I used the "combobox" property, which exposes a normal combobox.

I had a

 Dictionary<Control, string> controls = new Dictionary<Control, string>();

Binding code (Sorin Comanescu's solution - worked like a charm):

 controls.Add(pictureBox1, "Image");
 controls.Add(dgvText, "Text");
 cbFocusedControl.ComboBox.DataSource = new BindingSource(controls, null);
 cbFocusedControl.ComboBox.ValueMember = "Key";
 cbFocusedControl.ComboBox.DisplayMember = "Value";

The problem was that when I tried to get the selected value, I didn't realize how to retrieve it. After several attempts I got this:

 var control = ((KeyValuePair<Control, string>) cbFocusedControl.ComboBox.SelectedItem).Key

Hope it helps someone else!

回答3:

        var colors = new Dictionary < string, string > ();
        colors["10"] = "Red";

Binding to Combobox

        comboBox1.DataSource = new BindingSource(colors, null);
        comboBox1.DisplayMember = "Value";
        comboBox1.ValueMember = "Key";

Full Source...Dictionary as a Combobox Datasource

Jeryy

回答4:

userListComboBox.DataSource = userCache.ToList();
userListComboBox.DisplayMember = "Key";

回答5:

A dictionary cannot be directly used as a data source, you should do more.

SortedDictionary<string, int> userCache =  UserCache.getSortedUserValueCache();
KeyValuePair<string, int> [] ar= new KeyValuePair<string,int>[userCache.Count];
userCache.CopyTo(ar, 0);
comboBox1.DataSource = ar; new BindingSource(ar, "Key"); //This line is causing the error
comboBox1.DisplayMember = "Value";
comboBox1.ValueMember = "Key";

回答6:

If this doesn't work why not simply do a foreach loop over the dictionary adding all the items to the combobox?

foreach(var item in userCache)
{
    userListComboBox.Items.Add(new ListItem(item.Key, item.Value));
}

回答7:

Use -->

comboBox1.DataSource = colors.ToList();

Unless the dictionary is converted to list, combo-box can't recognize its members.

回答8:

Just Try to do like this....

SortedDictionary<string, int> userCache = UserCache.getSortedUserValueCache();

    // Add this code
    if(userCache != null)
    {
        userListComboBox.DataSource = new BindingSource(userCache, null); // Key => null
        userListComboBox.DisplayMember = "Key";
        userListComboBox.ValueMember = "Value";
    }

来源：https://stackoverflow.com/questions/6412739/binding-combobox-using-dictionary-as-the-datasource

标签

.net

winforms

combobox

datasource