In VB.net, how do I save changes to app.config

Question

I have a couple of appSettings in my app.config file, with default values:

<appSettings>
  <add key="Foo" value="one"/>
  <add key="Bar" value="two"/>
</appSettings>

which I am able to read and put the values into a TextBox and a ComboBox

I have this code to save the changes made to those two, but the changes I make are not saved to the app.config file itself, so when I close the program and open it again, the values go back to the defaults.

Private Sub ButtonSaveSettings_Click(sender As Object, e As EventArgs) Handles ButtonSaveSettings.Click
    Dim settings = System.Configuration.ConfigurationManager.AppSettings

    settings.Set("Foo", TextBoxFoo.Text)
    settings.Set("Bar", ComboBoxBar.SelectedItem.ToString)
End Sub

What do I need to do to get the updated values to persist to the app.config file?

(edit: The answers on the duplicate were not for VB and didn't solve this issue.)

possible duplicate of [ConfigurationManager doesn't save settings](http://stackoverflow.com/questions/4216809/configurationmanager-doesnt-save-settings) — TyCobb, May 20 '15 at 23:34
The answers there didn't help. But I've figured it out now, I'll post an answer. — mike, May 21 '15 at 04:02

score 3 · Accepted Answer · answered May 21 '15 at 04:07

I didn't need to mess around with the ConfirgurationManager by changing my app.config file to this (using Solution Explorer -> My Project -> Settings)

<userSettings>
    <MyProject.My.MySettings>
        <setting name="Foo" serializeAs="String">
            <value>one</value>
        </setting>
        <setting name="Bar" serializeAs="String">
            <value>two</value>
        </setting>
    </MyProject.My.MySettings>
</userSettings>

I was able to use this code to save the updated values for my settings

Private Sub ButtonSaveSettings_Click(sender As Object, e As EventArgs) Handles ButtonSaveSettings.Click
    My.Settings.Foo = TextBoxFoo.Text
    My.Settings.Bar = ComboBoxBar.SelectedItem.ToString
End Sub

score 3 · Answer 2 · answered May 21 '15 at 08:17

3

Another method would be to use

My.Settings.Save()

In your ButtonSaveSettings.Click Event. Otherwise, the settings would not be retentive

answered May 21 '15 at 08:17

WashirePie

75
9

score 2 · Answer 3 · answered Sep 09 '20 at 23:26

the options above is for setting not for app settings keys. I had the same problem and I solved it with the following code

    Dim config As Configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None)

    config.AppSettings.Settings("yourKeyName").Value = YourNewValue        
    
    config.Save(ConfigurationSaveMode.Modified) 

    ConfigurationManager.RefreshSection("appSettings")

it is very important to save changes!!! refresh is optional (RefreshSection), if you need to immediately use the updated values

In VB.net, how do I save changes to app.config

3 Answers3