CODEWITHSUNDEEP
vb.net
Pickle
Pickle

Reputation: 1124

Populating a combobox from another combobox

I have two comboboxes; one contains a list of countries, and the other contains a list of cities. How do I set it so that when you select a country, that country's cities become visible in the other combobox?

I suppose this is basically creating the item collection for the second box based on the selected value of the first one.

EDIT: I'm looking for something like this:

If cboCountry.Text = "Australia" Then
 cboCity.Collection("Melbourne, "Sydney")
End If

Upvotes: 0

Views: 3158

Answers (2)

Konrad Rudolph
Konrad Rudolph

Reputation: 546045

Load the data into a Dictionary(Of String, List(Of String)) which contains the mapping from countries to cities.

Then just look the selected country up in the dictionary and iterate over its values.

Here’s an example of how to do the latter part. This assumes that you’ve already loaded your dictionary data (obviously don’t hard-code the values in code):

' As a private Form variable:
Private cities As New Dictionary(Of String, List(Of String))()
' … Load data in Form_Load.

' In the citiesCombo.SelectedValueChanged event of the combo box:
cboCity.Items.Clear()
For Each city As var In cities(cboCountry.Text)
    cboCity.Items.Add(city)
Next

If you just want to test this with some toy data, here’s some:

Private cities As New Dictionary(Of String, List(Of String))() From { _
    {"England", New List(Of String)() From {"London", "Darthmouth", "Oxford", "Cambridge"}}, _
    {"Wales", New List(Of String)() From {"Cardiff", "Swansea"}}, _
    {"Scotland", New List(Of String)() From {"Edinburgh", "Glasgow", "Aberdeen"}} _
}

Upvotes: 1

Cubsoft
Cubsoft

Reputation: 1157

EDIT

Going on your edit, i have changed the code, this should be what you're looking for :)

Put this in to the combo box 1 selected value changed event and should work.

          Private Sub cboCountry_SelectedValueChanged(sender As System.Object, e As System.EventArgs) Handles cboCountry.SelectedValueChanged

            If cboCountry.Text = "England" Then
               cboCity.Items.Add("London")
            End If

          End Sub

Upvotes: 0

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