c# - 如果需要，如何搜索和更改 XML？

Question

我得到了这样的 XML:

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

所以我这样加载xml

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

并且我给出了 ServerName、DataBase、User 和 Pass 的组合。

如果我已经将此组合添加为 <Conn>，如何 checkin XML (那是 4 个属性)如果我还没有添加它，如何添加它？

Answer 1

另一种选择(如果您使用的是 .Net 3.5 或更高版本)是跳过 XmlDocument 并使用 LINQ to XML，在我看来，这会产生更清晰的代码:

// 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);