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AppSettings Implementation for Compact Framework

, 23 Mar 2004
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Learn how to create a settings class that will make it easy to access and store your application settings.

Sample Image - SaveSettings.jpg

Introduction

The .NET Compact Framework does not contain an AppSettings class like the full framework. On the full .NET Framework a developer could gain access to settings stored in the App.Config file by creating a name value collection from the System.Configuration.ConfigurationSettings.AppSettings class. As an advocate of uniformity, I wanted to create something that had similar functionality on the Compact Framework. This article will show you what I came up with.

Using the code

My first step was to create an XML file that looked a lot like the App.Config file in .NET.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <appSettings>
        <add key="ServerIP" value="192.168.5.22" />
        <add key="UserName" value="testuser" />
        <add key="Password" value="jdhs822@@*" />
        <add key="PhoneNumber" value="5555555555" />
        <add key="TimeOut" value="60" />
        <add key="LastTransmit" value="03/03/2004 9:12:33 PM" />
        <add key="DatabasePath" value="\Program Files\DB\test.sdf" />
    </appSettings>
</configuration>

I named this file Settings.xml and added it to my project with a build action of content. This ensures that the file will get downloaded to my program's executing folder.

My next step was to create a new class called Settings. This class contains only static members so the settings are accessed from the file only once during program execution and the entire program will have easy access to these values.

I wanted the settings to be loaded as soon as the settings were accessed, so I created a static constructor and placed my XML parsing code inside the constructor.

m_settings is a NameValueCollection that stores all of the settings.

public class Settings
{
    private static NameValueCollection m_settings;
    private static string m_settingsPath;

    // Static Ctor
    static Settings()
    {
        // Get the path of the settings file.
        m_settingsPath = Path.GetDirectoryName(
        System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase);
        m_settingsPath += @"\Settings.xml";

        if(!File.Exists(m_settingsPath))
            throw new FileNotFoundException(
                              m_settingsPath + " could not be found.");

        System.Xml.XmlDocument xdoc = new XmlDocument();
        xdoc.Load(m_settingsPath);
        XmlElement root = xdoc.DocumentElement;
        System.Xml.XmlNodeList nodeList = root.ChildNodes.Item(0).ChildNodes;

        // Add settings to the NameValueCollection.
        m_settings = new NameValueCollection();
        m_settings.Add("ServerIP", nodeList.Item(0).Attributes["value"].Value);
        m_settings.Add("UserName", nodeList.Item(1).Attributes["value"].Value);
        m_settings.Add("Password", nodeList.Item(2).Attributes["value"].Value);
        m_settings.Add("PhoneNumber",
                                  nodeList.Item(3).Attributes["value"].Value);
        m_settings.Add("TimeOut", nodeList.Item(4).Attributes["value"].Value);
        m_settings.Add("LastTransmit",
                                  nodeList.Item(5).Attributes["value"].Value);
        m_settings.Add("DatabasePath",
                                  nodeList.Item(6).Attributes["value"].Value);
    }
}

Now, we need some public accessors to retrieve the values from the NameValueCollection.

public static string ServerIP
{
    get { return m_settings.Get("ServerIP"); }
    set { m_settings.Set("ServerIP", value); }
}

public static string UserName
{
    get { return m_settings.Get("UserName"); }
    set { m_settings.Set("UserName", value); }
}

// ... And so on

The only thing left to do is to add a method for updating our settings. The XmlTextWriter class provides us with a light-weight mechanisim for writing xml to a FileStream. We iterate through the NameValueCollection and create the settings in xml.

public static void Update()
{
    XmlTextWriter tw = new XmlTextWriter(m_settingsPath,
                                       System.Text.UTF8Encoding.UTF8);
    tw.WriteStartDocument();
    tw.WriteStartElement("configuration");
    tw.WriteStartElement("appSettings");

    for(int i=0; i<m_settings.Count; ++i)
    {
        tw.WriteStartElement("add");
        tw.WriteStartAttribute("key", string.Empty);
        tw.WriteRaw(m_settings.GetKey(i));
        tw.WriteEndAttribute();

        tw.WriteStartAttribute("value", string.Empty);
        tw.WriteRaw(m_settings.Get(i));
        tw.WriteEndAttribute();
        tw.WriteEndElement();
    }

    tw.WriteEndElement();
    tw.WriteEndElement();

    tw.Close();
}

Now we can easily access our settings from anywhere in our application!

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

pbrooks
Software Developer (Senior)
United States United States
Check out my blog! http://www.pagebrooks.com

Comments and Discussions

 
SuggestionUse key instead of id PinmemberMarownIOM9-Apr-14 6:10 
GeneralMy vote of 3 Pinmemberb0bi21-Jun-11 21:01 
GeneralDid exactly what it should PinmemberBernhard11-Mar-10 22:46 
GeneralMy vote of 1 PinmemberNedyalko Zhekov19-Jan-10 11:22 
QuestionLittle problem PinmemberMember #352815616-Mar-07 6:29 
GeneralAccess Violation Error Pinmemberr20j30-Nov-05 0:18 
GeneralVery Useful PinmemberPaul Baker18-Aug-05 10:54 
Really good, easy to follow, simple demo. I wanted to write a small pocket pc application to keep count on a number of different items where the user can add or delete new counters and increase any counter by one or reset the counter.
 
This demo provided the backbone code I needed for saving my counter values...with a small bit of tweaking it did exactly what I wanted and I'm sure saved me a good couple of hours rooting around looking at the documentation for xml manipulation in the compact framework.
 
Great job...thanks a lot.
GeneralXML File is not being copied over Pinmemberjfaubey2000@yahoo.com21-Jul-05 8:42 
GeneralRe: XML File is not being copied over Pinmemberzero_joker20-Nov-06 6:27 
GeneralRe: XML File is not being copied over PinmemberAgha.net20-Sep-07 11:44 
Generaltiny improvement Pinmemberflair6-Apr-05 21:33 
GeneralRe: tiny improvement Pinmemberflair6-Apr-05 21:34 
GeneralRe: tiny improvement Pinmemberflair6-Apr-05 21:36 
GeneralSystem.NullReferenceException Pinmemberwannafly12-Apr-04 7:36 
GeneralAny chance you could port it to VB PinmemberGeovani5-Apr-04 5:56 
GeneralRe: Any chance you could port it to VB Pinmembercyn3rgy14-Sep-10 0:45 
GeneralA misprint PinsussAlexey Mochalov21-Mar-04 20:47 
GeneralRe: A misprint Pinmemberpbrooks22-Mar-04 4:07 

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