Modifying Web.Config using SPWebConfigModification

Question

I wrote the following code in my feature receiver to add a connectionString in the web.config:

SPWebApplication webApp = SPWebApplication.Lookup(new Uri("http://devtools2012/sites/Test"));

SPWebConfigModification mod = new SPWebConfigModification("add[@name=\"MyConnection\"]", 
    "configuration/connectionStrings");

    mod.Owner = "ExcelServiceOwner";

    mod.Type = SPWebConfigModification.SPWebConfigModificationType.EnsureChildNode;

    mod.Value = String.Format("", "MyConnection", "Server=DEVWCMSDB2012;Database=BJS;Integrated Security=true", "System.Data.SqlClient");

    webApp.WebConfigModifications.Add(mod);

    webApp.Update();

    webApp.Farm.Services.GetValue<SPWebService>().ApplyWebConfigModifications();

However, it is failing with the following error:

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Failed to apply web.config modifications to Web application '9a38b727-bab9-44ad-93ba-a6c3b919d481'. Failed to apply web.config modifications to file 'C:\inetpub\wwwroot\wss\VirtualDirectories\80\web.config'. The Value property for EnsureChildNode cannot be set to an empty value.

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I appreciate any input you can extend me. Regards.

Answer 1

Unless it's a formatting issue with the question then the mod.Value = String.Format("", ...) is giving an empty string.

You want something like:

mod.Value = String.Format("<add name="{0}" connectionString="{1}" ProviderName="{2}" />", ...)