How to Change UserSettings value of one app from another app using VB.Net?

Question

Is it possible to change My.Settings.SomeString value of one targeted application from another application programmatically?

Example

The Value I want to change:

Answer 1

Yes, this is possible.

The My.Settings configurations are stored in a file that is located at the following location:

C:\ Users \ [your_username] \ AppData \ Local \ [app publisher] \ [name of the application] \ [app version #] \ user.config

I'm certain that you could programmatically load the XML of the user.config file for the target application into your application, adjust it, and then save it.

Upon opening the target application, the user.config file would be loaded like normal and any changes you made to the XML would be reflected.

Answer 2

The settings are saved in xml. By default the files is named Settings.settings and is located in Project Directory\My Project.

In your example + another setting, the file could look like this

<?xml version='1.0' encoding='utf-8'?>
<SettingsFile xmlns="http://schemas.microsoft.com/VisualStudio/2004/01/settings" 
              CurrentProfile="(Default)" GeneratedClassNamespace="My" 
              GeneratedClassName="MySettings" UseMySettingsClassName="true">
  <Profiles />
  <Settings>
    <Setting Name="SomeString" Type="System.String" Scope="User">
      <Value Profile="(Default)">This is some string</Value>
    </Setting>
    <Setting Name="SomeOtherString" Type="System.String" Scope="User">
      <Value Profile="(Default)">This is some other string</Value>
    </Setting>
  </Settings>
</SettingsFile>

You can generate vb.net classes from the XML if you have VS 2012 or newer. I did that, and here are the generated classes. (If you don't have at least VS 2012, you can still use Microsoft's XML Schema Definition Tool).

<System.Xml.Serialization.XmlTypeAttribute(AnonymousType:=True, [Namespace]:="http://schemas.microsoft.com/VisualStudio/2004/01/settings"), _
 System.Xml.Serialization.XmlRootAttribute([Namespace]:="http://schemas.microsoft.com/VisualStudio/2004/01/settings", IsNullable:=False)> _
Partial Public Class SettingsFile

    Private profilesField As Object
    Private settingsField() As SettingsFileSetting
    Private currentProfileField As String
    Private generatedClassNamespaceField As String
    Private generatedClassNameField As String
    Private useMySettingsClassNameField As Boolean

    Public Property Profiles() As Object
        Get
            Return Me.profilesField
        End Get
        Set(value As Object)
            Me.profilesField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlArrayItemAttribute("Setting", IsNullable:=False)> _
    Public Property Settings() As SettingsFileSetting()
        Get
            Return Me.settingsField
        End Get
        Set(value As SettingsFileSetting())
            Me.settingsField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property CurrentProfile() As String
        Get
            Return Me.currentProfileField
        End Get
        Set(value As String)
            Me.currentProfileField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property GeneratedClassNamespace() As String
        Get
            Return Me.generatedClassNamespaceField
        End Get
        Set(value As String)
            Me.generatedClassNamespaceField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property GeneratedClassName() As String
        Get
            Return Me.generatedClassNameField
        End Get
        Set(value As String)
            Me.generatedClassNameField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property UseMySettingsClassName() As Boolean
        Get
            Return Me.useMySettingsClassNameField
        End Get
        Set(value As Boolean)
            Me.useMySettingsClassNameField = value
        End Set
    End Property
End Class

<System.Xml.Serialization.XmlTypeAttribute(AnonymousType:=True, [Namespace]:="http://schemas.microsoft.com/VisualStudio/2004/01/settings")> _
Partial Public Class SettingsFileSetting

    Private valueField As SettingsFileSettingValue
    Private nameField As String
    Private typeField As String
    Private scopeField As String

    Public Property Value() As SettingsFileSettingValue
        Get
            Return Me.valueField
        End Get
        Set(value As SettingsFileSettingValue)
            Me.valueField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property Name() As String
        Get
            Return Me.nameField
        End Get
        Set(value As String)
            Me.nameField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property Type() As String
        Get
            Return Me.typeField
        End Get
        Set(value As String)
            Me.typeField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property Scope() As String
        Get
            Return Me.scopeField
        End Get
        Set(value As String)
            Me.scopeField = value
        End Set
    End Property
End Class

<System.Xml.Serialization.XmlTypeAttribute(AnonymousType:=True, [Namespace]:="http://schemas.microsoft.com/VisualStudio/2004/01/settings")> _
Partial Public Class SettingsFileSettingValue

    Private profileField As String
    Private valueField As String

    <System.Xml.Serialization.XmlAttributeAttribute()> _
    Public Property Profile() As String
        Get
            Return Me.profileField
        End Get
        Set(value As String)
            Me.profileField = value
        End Set
    End Property

    <System.Xml.Serialization.XmlTextAttribute()> _
    Public Property Value() As String
        Get
            Return Me.valueField
        End Get
        Set(value As String)
            Me.valueField = value
        End Set
    End Property
End Class

With these classes, you can serialize and deserialize the xml settings file. Of course, you can read and write to the settings file with xml serialization.

This complete solution demonstrates how to edit a setting

' define the path to the settings file
Dim settingsPath = "C:\Users\username\AppData\Local\Temporary Projects\ConsoleApplication1\My Project\Settings.settings"
Dim serializer As New XmlSerializer(GetType(SettingsFile))

Sub Main()
    Dim settingsObject As SettingsFile
    ' open the settings file for reading
    Using sr As New StreamReader(settingsPath) ' deserialize the xml file to the settings object
        settingsObject = CType(serializer.Deserialize(sr), SettingsFile)
    End Using
    Console.WriteLine("Available settings:") ' display the available settings
    Console.WriteLine(
        String.Join(Environment.NewLine, settingsObject.Settings.Select(
                    Function(s) String.Format("{0}: '{1}'", s.Name, s.Value.Value))))
    Console.WriteLine("Enter a setting name to be modified...")
    Dim settingNameToBeModified = Console.ReadLine()
    Dim settingToBeModified =
        settingsObject.Settings.
        Where(Function(s) s.Name.ToUpper() = settingNameToBeModified.ToUpper()).Single()
    Console.WriteLine(
        "Enter a new value for {0} (old value: '{1}')",
        settingToBeModified.Name, settingToBeModified.Value.Value)
    Dim newValue = Console.ReadLine()
    If EditSetting(settingToBeModified, newValue) Then
        Console.WriteLine("Saved new setting!")
    Else
        Console.WriteLine("Couldn't find setting '{0}'", settingNameToBeModified)
    End If
    Console.WriteLine("Press enter to exit")
    Console.ReadLine()
End Sub

Public Function EditSetting(settingObject As SettingsFileSetting, newValue As String)
    Try
        Console.WriteLine(
            "Enter a new value for {0} (old value: '{1}')",
            settingObject.Name, settingObject.Value.Value)
        settingObject.Value.Value = newValue
        Using sr As New StreamWriter(settingsPath) ' open the settings file again, for writing
            serializer.Serialize(sr, settingObject) ' serialize the settings object to the xml file
        End Using
        Console.WriteLine("Saved new setting!")
    Catch
        Return False
    End Try
End Function