Writing in Web.config file dynamically

Web.config allows the developers to change the configuration of the application without having to build the application. Its not a good idea to write to the configuration file dynamically as it will restart the application. But sometimes we need the feature to dynamically write to the config file. This can be the case when you allow the users to personalize the connection string. In this article we will see how we can dynamically write the connection string to the Web.config file.

Introduction:

Web.config allows the developers to change the configuration of the application without having to build the application. Its not a good idea to write to the configuration file dynamically as it will restart the application. But sometimes we need the feature to dynamically write to the config file. This can be the case when you allow the users to personalize the connection string. In this article we will see how we can dynamically write the connection string to the Web.config file.

What are we going to write?

Since, we are changing the connection string dynamically we will need to write the key as well as the database name to the configuration file.

<appSettings>

<add key="NorthwindConnectionString" value="Server=local;Database=Northwind;Trusted_Connection=true" />

</appSettings>

 

Interface:

Interface for this is pretty simple.

Implementation:

Now, let's see how we can dynamically write to the web.config file.

C# Code:

You will need to include the namespace System.xml. All we are doing is setting the <add tag which resides inside the <appSettings> tag in web.config file.

private void SetConfigSettings()

{

string path = Server.MapPath("Web.config");

string newConnectionString = @"Server=local;Database="+txtDatabaseName.Text+";Trusted_Connection=true";

XmlDocument xDoc = new XmlDocument();

xDoc.Load(path);

XmlNodeList nodeList = xDoc.GetElementsByTagName("appSettings");

XmlNodeList nodeAppSettings = nodeList[0].ChildNodes;

XmlAttributeCollection xmlAttCollection = nodeAppSettings[0].Attributes;

xmlAttCollection[0].InnerXml = txtKey.Text; // for key attribute

xmlAttCollection[1].InnerXml = newConnectionString; // for value attribute

xDoc.Save(path); // saves the web.config file

}

 

VB.NET Code:

Private Sub SetConfigSettings()
        Dim path As String = Server.MapPath("Web.config")
        Dim newConnectionString As String = ("Server=local;Database="  _
                    + (txtDatabaseName.Text + ";Trusted_Connection=true"))
        Dim xDoc As XmlDocument = New XmlDocument
        xDoc.Load(path)
        Dim nodeList As XmlNodeList = xDoc.GetElementsByTagName("appSettings")
        Dim nodeAppSettings As XmlNodeList = nodeList(0).ChildNodes
        Dim xmlAttCollection As XmlAttributeCollection = nodeAppSettings(0).Attributes
        xmlAttCollection(0).InnerXml = txtKey.Text
        ' for key attribute
        xmlAttCollection(1).InnerXml = newConnectionString
        ' for value attribute
        xDoc.Save(path)
        ' saves the web.config file         
    End Sub

Conclusion:

Although it's not a good idea to write to the configuration file dynamically but sometimes depending on the situation we might have to use that approach. I hope you liked the article, happy coding!