Question

I have a connection string as follows in app.config

<add name="CONN" connectionString="SERVER=SERVER\SQLEXPRESS;DATABASE=TRIAL_LINK;uid=sa;pwd=trial"
        providerName="System.Data.SqlClient" />

I have a form called DBLinker where i am giving an option to the user to select some other server and database.
For instance i am selecting Server name as “MAILSERVER” and database as “Actual”. I am overwriting the app.config file using the following code.

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

Dim mySection As ConnectionStringsSection = DirectCast(config.GetSection("CONN"),ConnectionStringsSection)
Dim conStr As String = "SERVER=MAILSERVER;DATABASE=Actual;uid=sa;pwd=trial"

config.ConnectionStrings.ConnectionStrings("CONN").ConnectionString = conStr
config.Save(ConfigurationSaveMode.Full)


ConfigurationManager.RefreshSection(config.AppSettings.SectionInformation.Name)

After this code i am trying to open a login form for the application. But when i am trying to access connection string here, it is fetching the former string instead of the updated one.

Answer 1

 Public Sub updateConfigFile(ByVal con As String)
        'updating config file
        Dim XmlDoc As New XmlDocument()
        'Loading the Config file
        XmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile)
        For Each xElement As XmlElement In XmlDoc.DocumentElement
            If xElement.Name = "connectionStrings" Then
                'setting the coonection string
                xElement.FirstChild.Attributes(2).Value = con
            End If
        Next
        'writing the connection string in config file
        XmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile)
    End Sub

I used this code to solve this problem.