Question

I seem to be having a problem with retrieving XML values with C#, which I know it is due to my very limited knowledge of C# and .XML.

I was given the following XML file

<PowerBuilderRunTimes>
    <PowerBuilderRunTime>
        <Version>12</Version>
        <Files>
            <File>EasySoap110.dll</File>
            <File>exPat110.dll</File>
            <File>pbacc110.dll</File>
        </File>
     </PowerBuilderRunTime>
</PowerBuilderRunTimes>

I am to process the XML file and make sure that each of the files in the exist in the folder (that’s the easy part). It’s the processing of the XML file that I have having a hard time with. Here is what I have done thus far:

var runtimeXml = File.ReadAllText(string.Format("{0}\\{1}", configPath, Resource.PBRuntimes));

var doc = XDocument.Parse(runtimeXml);
var topElement = doc.Element("PowerBuilderRunTimes");
var elements = topElement.Elements("PowerBuilderRunTime");

foreach (XElement section in elements)
{
    //pbVersion is grabbed earlier. It is the version of PowerBuilder
    if( section.Element("Version").Value.Equals(string.Format("{0}", pbVersion ) ) )
    {
        var files = section.Elements("Files");

        var fileList = new List<string>();

        foreach (XElement area in files)
        {
            fileList.Add(area.Element("File").Value);
        }
    }
}

My issue is that the String List is only ever populated with one value, “EasySoap110.dll”, and everything else is ignored. Can someone please help me, as I am at a loss.

Answer 1

Look at this bit:

var files = section.Elements("Files");

var fileList = new List<string>();

foreach (XElement area in files)
{
    fileList.Add(area.Element("File").Value);
}

You’re iterating over each Files element, and then finding the first File element within it. There’s only one Files element – you need to be iterating over the File elements within that.

However, there are definitely better ways of doing this. For example:

var doc = XDocument.Load(Path.Combine(configPath, Resource.PBRuntimes));
var fileList = (from runtime in doc.Root.Elements("PowerBuilderRunTime")
                where (int) runtime.Element("Version") == pbVersion
                from file in runtime.Element("Files").Elements("File")
                select file.Value)
               .ToList();

Note that if there are multiple matching PowerBuilderRunTime elements, that will create a list with all the files of all those elements. That may not be what you want. For example, you might want:

var doc = XDocument.Load(Path.Combine(configPath, Resource.PBRuntimes));
var runtime = doc.Root
                 .Elements("PowerBuilderRunTime")
                 .Where(r => (int) r.Element("Version") == pbVersion)
                 .Single();

var fileList = runtime.Element("Files")
                      .Elements("File")
                      .Select(x => x.Value)
                      .ToList();

That will validate that there’s exactly one matching runtime.