Check if an element exists in XML

问题:

XML:

<CONFIGURATION>
<Files>
    <File>D:\Test\TestFolder\TestFolder1\TestFile.txt</File>
    <File>D:\Test\TestFolder\TestFolder1\TestFile01.txt</File>
    <File>D:\Test\TestFolder\TestFolder1\TestFile02.txt</File>
    <File>D:\Test\TestFolder\TestFolder1\TestFile03.txt</File>
    <File>D:\Test\TestFolder\TestFolder1\TestFile04.txt</File>
</Files>
<SizeMB>3</SizeMB>
<BackupLocation>D:\Log backups\File backups</BackupLocation>
</CONFIGURATION>

Code:

private void btnLinq_Click(object sender, EventArgs e)
    {
        queryData(@"D:\WatchMe1\backupconfig1.xml");
    }

static void queryData(string xmlFile)
    {
        var xdoc = XDocument.Load(xmlFile);
        var configuration = xdoc.Element("CONFIGURATION");
        string sizeMB = configuration.Element("SizeMB").Value;
        string backupLocation = configuration.Element("BackupLocation").Value;
        //need a code here to check if element <File> exist before executing the file array
        string[] files = configuration.Element("Files").Elements("File").Select(c => c.Value).ToArray();

        foreach (string file in files)
        {
            Console.WriteLine(file);
        }
    }

I have an xml writer program that edits the above xml. The Files element can be changed to Folder element. I have another program that reads the values(file locations) and do something with it, I have to check first if the element is a Files or Folders element.

回答1:

You can check for element existence with something like

if(configuration.Elements("...").Any()){...}

But i'm not sure what you are asking here exactly...

回答2:

This may be what you want to do:

if(configutation.Elements.First("Files") != null)
{
    string[] files = configuration.Element("Files").Elements("File").Select(c => c.Value).ToArray();
}

Hope this helps!