c# - approach for saving user settings in a WPF ap

Question

What approach do you recommend for persisting user settings in a WPF windows (desktop) application? Note that the idea is that the user can change their settings at run time, and then can close down the application, then when starting up the application later the application will use the current settings. Effectively then it will appear as if the application settings do not change.

Q1 - Database or other approach? I do have a sqlite database that I will be using anyway hence using a table in the database would be as good as any approach?

Q2 - If Database: What database table design? One table with columns for different data types that one might have (e.g. string, long, DateTime etc) OR just a table with a string for the value upon which you have to serialize and de-serialize the values? I'm thinking the first would be easier, and if there aren't many settings the overhead isn't much?

Q3 - Could Application Settings be used for this? If so are there any special tasks required to enable the persistence here? Also what would happen regarding usage of the "default" value in the Application Settings designer in this case? Would the default override any settings that were saved between running the application? (or would you need to NOT use the default value)

Answer 1

You can store your settings info as Strings of XML in the Settings.Default. Create some classes to store your configuration data and make sure they are [Serializable]. Then, with the following helpers, you can serialize instances of these objects--or List<T> (or arrays T[], etc.) of them--to String. Store each of these various strings in its own respective Settings.Default slot in your WPF application's Settings.

To recover the objects the next time the app starts, read the Settings string of interest and Deserialize to the expected type T (which this time must be explcitly specified as a type argument to Deserialize<T>).

public static String Serialize<T>(T t)
{
    using (StringWriter sw = new StringWriter())
    using (XmlWriter xw = XmlWriter.Create(sw))
    {
        new XmlSerializer(typeof(T)).Serialize(xw, t);
        return sw.GetStringBuilder().ToString();
    }
}

public static T Deserialize<T>(String s_xml)
{
    using (XmlReader xw = XmlReader.Create(new StringReader(s_xml)))
        return (T)new XmlSerializer(typeof(T)).Deserialize(xw);
}

Answer 2

You can use Application Settings for this, using database is not the best option considering the time consumed to read and write the settings(specially if you use web services).

Here are few links which explains how to achieve this and use them in WPF -

User Settings in WPF

Quick WPF Tip: How to bind to WPF application resources and settings?

A Configurable Window for WPF

Answer 3

I wanted to use an xml control file based on a class for my VB.net desktop WPF application. The above code to do this all in one is excellent and set me in the right direction. In case anyone is searching for a VB.net solution here is the class I built:

Imports System.IO
Imports System.Xml.Serialization

Public Class XControl

Private _person_ID As Integer
Private _person_UID As Guid

'load from file
Public Function XCRead(filename As String) As XControl
    Using sr As StreamReader = New StreamReader(filename)
        Dim xmls As New XmlSerializer(GetType(XControl))
        Return CType(xmls.Deserialize(sr), XControl)
    End Using
End Function

'save to file
Public Sub XCSave(filename As String)
    Using sw As StreamWriter = New StreamWriter(filename)
        Dim xmls As New XmlSerializer(GetType(XControl))
        xmls.Serialize(sw, Me)
    End Using
End Sub

'all the get/set is below here

Public Property Person_ID() As Integer
    Get
        Return _person_ID
    End Get
    Set(value As Integer)
        _person_ID = value
    End Set
End Property

Public Property Person_UID As Guid
    Get
        Return _person_UID
    End Get
    Set(value As Guid)
        _person_UID = value
    End Set
End Property

End Class

Answer 4

I typically do this sort of thing by defining a custom [Serializable] settings class and simply serializing it to disk. In your case you could just as easily store it as a string blob in your SQLite database.

Answer 5

1. In all the places I've worked, database has been mandatory because of application support. As Adam said, the user might not be at his desk or the machine might be off, or you might want to quickly change someone's configuration or assign a new-joiner a default (or team member's) config.

2. If the settings are likely to grow as new versions of the application are released, you might want to store the data as blobs which can then be deserialized by the application. This is especially useful if you use something like Prism which discovers modules, as you can't know what settings a module will return. The blobs could be keyed by username/machine composite key. That way you can have different settings for every machine.

3. I've not used the in-built Settings class much so I'll abstain from commenting. :)

Answer 6

I also prefer to go with serialization to file. XML files fits mostly all requirements. You can use the ApplicationSettings build in but those have some restrictions and a defined but (for me) very strange behavior where they stored. I used them a lot and they work. But if you want to have full control how and where they stored I use another approach.

1. Make a class Somewhere with all your settings. I named it MySettings
2. Implement Save and Read for persistence
3. Use them in you application-code

Advantages:

• Very Simple approach.
• One Class for Settings. Load. Save.
• All your Settings are type safe.
• You can simplify or extend the logic to your needs (Versioning, many Profiles per User, etc.)
• It works very well in any case (Database, WinForms, WPF, Service, etc...)
• You can define where to store the XML files.
• You can find them and manipulate them either by code or manual
• It works for any deployment method I can imagine.

Disadvantages: - You have to think about where to store your settings files. (But you can just use your installation folder)

Here is a simple example (not tested)-

public class MySettings
{
    public string Setting1 { get; set; }
    public List<string> Setting2 { get; set; }

    public void Save(string filename)
    {
        using (StreamWriter sw = new StreamWriter(filename))
        {
            XmlSerializer xmls = new XmlSerializer(typeof(MySettings));
            xmls.Serialize(sw, this);
        }
    }
    public MySettings Read(string filename)
    {
        using (StreamReader sw = new StreamReader(filename))
        {
            XmlSerializer xmls = new XmlSerializer(typeof(MySettings));
            return xmls.Deserialize(sw) as MySettings;
        }
    }
}

And here is how to use it. It's possible to load default values or override them with the user's settings by just checking if user settings exist:

public class MyApplicationLogic
{
    public const string UserSettingsFilename = "settings.xml";
    public string _DefaultSettingspath = 
        Assembly.GetEntryAssembly().Location + 
        "\\Settings\\" + UserSettingsFilename;

    public string _UserSettingsPath = 
        Assembly.GetEntryAssembly().Location + 
        "\\Settings\\UserSettings\\" + 
        UserSettingsFilename;

    public MyApplicationLogic()
    {
        // if default settings exist
        if (File.Exists(_UserSettingsPath))
            this.Settings = Settings.Read(_UserSettingsPath);
        else
            this.Settings = Settings.Read(_DefaultSettingspath);
    }
    public MySettings Settings { get; private set; }

    public void SaveUserSettings()
    {
        Settings.Save(_UserSettingsPath);
    }
}

maybe someone get's inspired by this approach. This is how I do it now for many years and I'm quite happy with that.