Select parent node by children via XmlDocument

Question

Help please, I have the xml file,

<Users>
 <User FullName="" Name="sa">
  <userAvatarCache>-1</userAvatarCache>
  <description></description>
  <email></email>
  <phone></phone>
  <UserActive>true</UserActive>
 </User>

 <User FullName="asfgd" Name="stest">
  <userAvatarCache>-1</userAvatarCache>
  <description>aasad</description>
  <email>test@ukr.net</email>
  <phone>sdafdsfds0850</phone>
  <UserActive>true</UserActive>
 </User>
</Users>

I need to select FullName by email . I got all structure using

 XmlDocument xmlDoc = new XmlDocument();
 xmlDoc.Load(res.GetResponseStream());
 XmlNode xmlNode = xmlDoc.DocumentElement.SelectSingleNode("User");

Now I need only 1 result (fullname) by email. How I can do it correct? Thanks

Answer 1

Please google XPath , and try to use it. Note that using XmlDocument for large file is a very bad idea.

Code:

    var rawXml = @"<Users>
                 <User FullName="""" Name=""sa"">
                  <userAvatarCache>-1</userAvatarCache>
                  <description></description>
                  <email></email>
                  <phone></phone>
                  <UserActive>true</UserActive>
                 </User>

                 <User FullName=""asfgd"" Name=""stest"">
                  <userAvatarCache>-1</userAvatarCache>
                  <description>aasad</description>
                  <email>test@ukr.net</email>
                  <phone>sdafdsfds0850</phone>
                  <UserActive>true</UserActive>
                 </User>
                </Users>";

     XmlDocument xmlDoc = new XmlDocument();
     xmlDoc.LoadXml(rawXml);
     string email = "test@ukr.net";
     string selector = string.Format("User[email=\"{0}\"]", email);
     XmlNode xmlNode = xmlDoc.DocumentElement.SelectSingleNode(selector);

     if(xmlNode != null)
     {      
        string fullName = xmlNode.Attributes["FullName"].Value;

        Console.WriteLine(fullName);
     }

Answer 2

XPath to select element based on childs child value covers this quite well.

string xmlString = @"
 <Users>
  <User FullName='' Name='sa'>
   <userAvatarCache>-1</userAvatarCache>
   <description></description>
   <email></email>
   <phone></phone>
   <UserActive>true</UserActive>
  </User>
  <User FullName='asfgd' Name='stest'>
   <userAvatarCache>-1</userAvatarCache>
   <description>aasad</description>
   <email>test@ukr.net</email>
   <phone>sdafdsfds0850</phone>
   <UserActive>true</UserActive>
  </User>
 </Users>";

XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(xmlString);
XmlNode xmlNode = xmlDoc.DocumentElement.SelectSingleNode("./User[email = 'test@ukr.net']");