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First Value of dictionary not getting assigned to combobox in C#

I am using Dictionary collection in C#. I want to display first value of dictionary
to combo box so that combo box by default shows first value.but instead of the first value null value get assigned.
I tried following code:
Dictionary<string, string> sampleDictionary = new Dictionary<string, string>();
sampleDictionary.add("ABC","XYZ");
sampleDictionary.add("JKL","PQR");
comboBox.SelectedValue=sampleDictionary.Values.First();

Try comboBox.SelectedIndex = 0;

You should add the values of the dictionary to your comboBox as follows:
Dictionary<string, string> sampleDictionary = new Dictionary<string, string>();
comboBox.DataSource = new BindingSource(sampleDictionary, null);
comboBox.DisplayMember = "Key";
comboBox.ValueMember = "Value";
Then, you could try: comboBox.SelectedIndex = 0;

Invalid Cast Error when trying to read "Value" from a ListBox Key-Value pair

I'm using Visual Studio 2010 express and working on a C# WinForms application.
My form has a ListBox object (listData) which has its DataSource set to use a Key-Value paired Dictionary object (dictionary).
This is the Dictionary and how it is assigned as a DataSource to listData-
Dictionary<string, uint> dictionary = new Dictionary<string, uint>();`
listData.DataSource = new BindingSource(dictionary, null);
listData.DisplayMember = "Key";
listData.ValueMember = "Value";
And when debugging I see that the "Value" is being assigned correctly and is clearly a number. Yet when I try to accept the same "Value" into a uint lastSelectedIndex, I get this cast error-
What am I doing wrong here?
This actually worked for me:
lastSelectedIndex = ((KeyValuePair<string, uint>)listData.SelectedItem).Value;

You should change this line.
listData.DataSource = new BindingSource(dictionary, null);
to
listData.DataSource = dictionary;
The BindingSource constructor requires two parameters. first one is for data source and second one for DataMember (ValueMember as we can say). You have specified null value into second parameter that's why BindingSource has taken whole KeyValuePair object as a DataMember.
I don't think that you need to create object of BindingSource class to bind the Dictionary class. but, if you still want to use then you should also specify the DataMember in second parameter.
listData.DataSource = new BindingSource(dictionary, "Value");
But, I don't know whether it will work or not. i haven't tried like this before.
The another approach is to convert the SelectedValue into KeyValuePair object and get the Value from it.
uint lastSelectedIndex = ((KeyValuePair<string, uint>)listData.SelectedValue).Value
You are trying to cast KeyValuePair object into uint. So, it cannot be convertable. You have to convert it into KeyValuePair type first then get the value from Value property of that object.
I would like to suggest you to create another class where the class is having two properties
public class MyDataClass
{
public uint Value{ get; set;}
public string Display{get;set;}
public MyDataClass(string display, uint val)
{
Display = display;
Value = val;
}
public override string ToString()
{
return this.Display;
}
}
The create a List<MyDataClass> object and fill the data into it.
Now you can assig that List object directly into that List control.
List<MyDataClass> lstItems = new List<MyDataClass>();
lstItems.Add(new MyDataClass("Item 1", 1));
lstItems.Add(new MyDataClass("Item 2", 2));
lstItems.Add(new MyDataClass("Item 3", 3));
listData.DataSource = lstItems;
listData.DisplayMember = "Display";
listData.ValueMember = "Value";

The reason for this issue is the order you have used to assign the DataSource and the ListBox' ValueMember property. If you assign the DataSource as last step it works:
Dictionary<string, uint> dictionary = new Dictionary<string, uint>();
dictionary.Add("1", 1);
dictionary.Add("2", 2);
dictionary.Add("3", 3);
listData.DisplayMember = "Key";
listData.ValueMember = "Value";
var bs = new BindingSource();
bs.DataSource = dictionary;
listData.DataSource = bs; // as last step
The ListBox' SelectedIndexChanged event will be triggered as soon as you assign the DataSource. Since you haven't specified the ValueMember at that time you get the InvalidCastException.

ValueMember from ComboBox.Items[i] using WinForms c#

I fill out a ComboBox using below code:
cbxLines.DisplayMember = "Value";
cbxLines.ValueMember = "Key";
cbxLines.DataSource = new BindingSource(GetProductionLines(), null);
private Dictionary<int, string> GetProductionLines()
Now I want to fill out a ListView with every DisplayMember from the ComboBox among other info:
lvSelectedSetup.Items.Clear();
for (int i = 0; i <= cbxLines.Items.Count - 1; i++)
{
ListViewItem item = new ListViewItem();
item.SubItems.Add(cbxLines.Items[i].ToString()); <-- How to Get DisplayMember
item.SubItems.Add(cbxFromDate.Text);
item.SubItems.Add(cbxToDate.Text);
lvSelectedSetup.Items.Add(item);
}
But I don't know how to get either the ValueMember or DisplayMember from the ComboBox.
I was trying doing the following, but get stuck:
item.SubItems.Add(cbxLines.Items[i].GetType().GetProperty(cbxLines.ValueMember).GetValue(cbxLines,null))
Any Advice?

Gets the key in the key/value pair.
((KeyValuePair<int, string>)cbxLines.Items[i]).Key
Gets the value in the key/value pair.
((KeyValuePair<int, string>)cbxLines.Items[i]).Value

comboBox select for first value

I have simple comboBox with:
cb_listaUczniow.ValueMember = "Key";
cb_listaUczniow.DisplayMember = "Value";
And I have constructor for this Form (classID is not important yet):
MyForm(int classID, string selectedName)
{
cb_listaUczniow.ValueMember = "Key";
cb_listaUczniow.DisplayMember = "Value";
comboBox.DataSource = new BindingSource(makeList(classID), null);
}
makeList return Dictionary
and How i can select in comboBox item with "Value" (displayMember) where names selectedName?
for example (pseudo-Code):
MyForm(3, "Gall Anonim") -> comboBox.Item.Selected = comboBox.Item.where("Value" == "Gall Anonim");
How i can set it?

If I understand this correctly, you can simply set ComboBox's SelectedValue property to the corresponding value :
comboBox.SelectedValue = 3;
That will make "Gall Anonim" the selected item of the ComboBox.

Binding empty dictionary to a listbox

When i try to bind a dictionary to a listbox I get an ArgumentException. Cannot bind to the new value member.
I use the following code.
Can any one tell me what is wrong. Because when i enter i row in the dictionary its working fine...
this.contactpersonenListBox = new Dictionary<int, string>();
lsContactpersonen.DataSource = new BindingSource(this.contactpersonenListBox, null);
lsContactpersonen.DisplayMember = "Value";
lsContactpersonen.ValueMember = "Key";

It doesn't make a ton of sense to bind an empty dictionary since the dictionary object doesn't report any changes, so adding an item to the dictionary after setting the data source won't show up in the ListBox.
But to get rid of the error, try setting it like this:
BindingSource b = new BindingSource();
b.DataSource = this.contactpersonenListBox;
lsContactpersonen.DisplayMember = "Value";
lsContactpersonen.ValueMember = "Key";
lsContactpersonen.DataSource = b;