使用Linq而不是foreach

Question

我想从另一个项目的外部app.config（appSettings）加载一些配置，加载的值必须保存在我的一些属性中。这里（参见代码中的注释）是我想做的事：

XmlDocument xmlDoc = MyXmlDocument; 
if (xmlDoc != null) 
{ 
    XmlNodeList appSettings = xmlDoc.SelectNodes("/configuration/appSettings/add"); 
    if (appSettings != null && appSettings.Count > 0) 
    { 
     foreach (XmlNode node in appSettings) 
     { 
      XmlAttribute keyAttr = node.Attributes["key"]; 
      if (keyAttr != null) 
      { 
       if (keyAttr.Value == "MyProperty1NameInConfigFile") MyProperty1 = node.Attributes["value"].Value; 
       // .... 
      } 
     } 


     // Instead of using foreach loop, I want to use Linq like this: 
     var node = get me the node that has the keyAttribute.Value == "MyProperty1NameInConfigFile" 
     MyProperty1 = node.Attributes["value"].Value; 

     // If I got this, then I can later use another method for each property like this: 
     SaveConfigToMyProperty(ref MyProperty1, "MyProperty1NameInConfigFile"); 
     SaveConfigToMyProperty(ref MyProperty2, "MyProperty2NameInConfigFile"); 
     // ... 
    } 
} 

Answer 1

如果你投你的XmlDocument到IEnumerable<XmlNode>你可以得到所有的乐趣LINQ查询。之后，你可以抓住你喜欢的任何东西。也许这样？

var node = xmlDoc.SelectNodes("/configuration/appSettings/add").Cast<XmlNode>() 
    .Where(n => n.Attributes["key"].Value == "MyProperty1NameInConfigFile"); 

Answer 2

这是一个XElement解决方案，更适合与Linq合作;

string xml = "";//xml as string; 
var txtReader = new XmlTextReader(xml, XmlNodeType.Element); 
var root = XElement.Load(txtReader); 

var node = root.XPathSelectElements("/configuration/appSettings/add") 
       .FirstOrDefault(n => 
        n.Attributes["key"] != null && 
        n.Attributes["key"].Value == "MyProperty1NameInConfigFile");