Question

I got XML like this:

 <Type> 
   <Connections>
      <Conn ServerName="serv1" DataBase="Persons" User="admin" Pass="123"/>
      <Conn ServerName="serv2" DataBase="Type123" User="admin" Pass="123"/>
   </Connections>
   <UDLFiles />
 </Type> 

so I load the xml like this

XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(path);

and I have given a combination of ServerName, DataBase, User and Pass.

How to check in the XML if I have already added this combination as a <Conn> (those are 4 attributes) and how to add it if I havent added it yet?

Answer 1

Another option (if you are using .Net 3.5 or higher) is to skip XmlDocument and use LINQ to XML which, in my opinion, results in cleaner code:

// Load the XML from file
XElement docElem = XElement.Load(path);
// Get the Connections element. This code assumes there will always be exactly one.
XElement connectionsElem = docElem.Elements("Connections").Single();

// Check if there is already a Conn element with the required attribute value combination
if (!connectionsElem.Elements("Conn").Any(connElem =>
    (string)connElem.Attribute("ServerName") == serverName &&
    (string)connElem.Attribute("DataBase") == dataBase &&
    (string)connElem.Attribute("User") == user &&
    (string)connElem.Attribute("Pass") == pass)) {

    // Otherwise add such a Conn element
    connectionsElem.AddFirst(
        new XElement("Conn",
            new XAttribute("ServerName", serverName),
            new XAttribute("DataBase", dataBase),
            new XAttribute("User", user),
            new XAttribute("Pass", pass)
        )
    );
}

// Write the XML to file again.
docElem.Save(path);