Create a Custom Settings Provider to Share Settings Between Applications

Imports System.Security.Permissions
Imports System.Configuration
Imports System.Collections.Specialized

<PermissionSetAttribute(SecurityAction.InheritanceDemand, Name:="FullTrust")> _
<PermissionSetAttribute(SecurityAction.LinkDemand, Name:="FullTrust")> _
Public Class LinqSettingsProvider
    Inherits SettingsProvider

    Private conn As String

    Public Sub New()
        'Sets the connection string to use MDF file included with this demo (TestConsole/bin/debug)
        'Change to a connection string for your database.
        Dim dbpath = AppDomain.CurrentDomain.BaseDirectory & "Netrudder.mdf"
        conn = "Data Source=.\SQLEXPRESS;AttachDbFilename=""" & dbpath & _
                """;Integrated Security=True;User Instance=True"
    End Sub

    Public Overrides Sub Initialize(ByVal name As String, ByVal col As NameValueCollection)
        MyBase.Initialize(Me.ApplicationName, col)
    End Sub

    Public Overrides Property ApplicationName() As String
        Get
            ApplicationName = System.Reflection.Assembly.GetExecutingAssembly().GetName().Name
        End Get
        Set(ByVal value As String)
            ' Do nothing.
        End Set
    End Property

    ''' <summary>
    ''' This method retrieves settings values from the data source.
    ''' The return object, SettingsPropertyValueCollection, is consumable by any class 
    ''' implementing ApplicationSettingsBase, for example NetrudderSettings
    ''' </summary>
    ''' <param name="context">Provides some additional contextual information</param>
    ''' <param name="collection">Collection of settings properties supplied by the settings class (e.g. NetrudderSettings)</param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Overrides Function GetPropertyValues(ByVal context As SettingsContext, _
                                                ByVal collection As SettingsPropertyCollection) As SettingsPropertyValueCollection

        Dim settings = New SettingsPropertyValueCollection

        Try            
            Using db As New NetrudderDataContext(conn)
                For Each propDef As SettingsProperty In collection
                    'Compiler will issue a warning if we attempt to use the iteration variable
                    'in a lambda expression, so we reassign propDef to a new variable
                    Dim lmb_propDef = propDef
                    'Create a new instance of SettingsPropertyValue from the property definition
                    Dim setting = New SettingsPropertyValue(propDef)

                    'Query the database for the one setting that is enabled and 
                    'has the name matching the name of the property
                    Dim settingEntity = db.Settings.SingleOrDefault(Function(s) _
                                            s.Name = lmb_propDef.Name And _
                                            s.Enabled = True)

                    If settingEntity IsNot Nothing Then
                        'If a matching property is found, its value is used.                    
                        setting.PropertyValue = settingEntity.Value
                    Else
                        'Do nothing: the default property value is used instead.
                    End If

                    'Indicate that the setting has not changed
                    setting.IsDirty = False
                    'Add the setting to the collection to be returned to the settings class
                    settings.Add(setting)
                Next
            End Using
        Catch ex As Exception
            'TODO
        End Try

        'Return the collection to the settings class
        Return settings

    End Function


    ''' <summary>
    ''' This method updates the settings in the data source.
    ''' CAUTION: Before you use this code in produciton, please consider adding security
    ''' </summary>
    ''' <param name="context"></param>
    ''' <param name="collection"></param>
    ''' <remarks></remarks>
    Public Overrides Sub SetPropertyValues(ByVal context As SettingsContext, _
                                           ByVal collection As SettingsPropertyValueCollection)
        Try
            Using db As New NetrudderDataContext(conn)
                For Each setting As SettingsPropertyValue In collection
                    'If the setting value has changed, update the data source
                    If setting.IsDirty Then
                        'Create a new variable for use in the lambda expression
                        Dim lmb_setting = setting
                        'Update the correct entity with the new value of the setting property
                        db.Settings.Single(Function(s) s.Name = lmb_setting.Name) _
                            .Value = setting.PropertyValue
                    End If
                Next
                'Persist to database
                db.SubmitChanges()
            End Using
        Catch ex As Exception
            'TODO
        End Try
    End Sub

End Class