C# finding and replacing attributes XML

Question

I have an output XML file with the following structure

<OFBM time="10:32" date="06.10.2017" saveName="Unnamed save">
<folder name="file:///C:/Users/AD/Downloads" />
<folder name="file:///C:/Users/AD/Desktop/t" />
<folder name="file:///C:/ProgramData/OFBM" />
</OFBM>

date and time combination are unique. How based on time, and date, I can parse a value that will change the saveName attribute? What's the best way of doing it?

This is what I wrote up

    public void saveNames(string time, string date, string folderName)
    {
    if(folderName == "Unnamed save")
    return;
    XElement root = XElement.Load(pathToXml);
        IEnumerable<XElement> address =
            from el in root.Elements("OFBM")
            where (string)el.Attribute("time") == time
            where (string)el.Attribute("date") == date
            select el;
        foreach (XElement el in address.Elements("saveName"))
        {
            el.ReplaceWith(folderName);

        }
        root.Save(pathToXml);

    }

Also tried this

            //  <OFBM time="10:30" date="06.10.2017" saveName="Unnamed save">
        XPathDocument document = new XPathDocument(pathToXml);
        //The XPathNavigator object is used for read-only XPath queries. The XPath queries may return a resulting value or many nodes
        XPathNavigator documentNav = document.CreateNavigator();
        // This expression uses standard XPath syntax.
        string filter = "@*";
        XPathNodeIterator NodeIter = documentNav.Select(filter);
        while (NodeIter.MoveNext())
        {
            Console.WriteLine("Save: {0}", NodeIter.Current.Value);
        };

PS. My code changes nothing, however.

PinBack · Accepted Answer · 2017-10-06 08:44:54Z

If you have only the Xml Snippet (like in your example) you can use this code:

if (root.Attribute("time").Value == time && 
    root.Attribute("date").Value == date &&
    root.Attribute("saveName") != null)
{
    root.Attribute("saveName").Value = folderName;
}

root is your OFBM Element ... therefore root.Element("OFBM") is null

EDIT:

If you have a xml with several OFBM elements (i think you have more than one). Use this:

var address = root.Elements("OFBM").Where(element =>
    element.Attribute("time").Value == time &&
    element.Attribute("date").Value == date &&
    element.Attribute("saveName") != null);

foreach (XElement el in address)
{
    el.Attribute("saveName").Value = folderName;
}

Xml Example:

<root>
  <OFBM time="10:32" date="06.10.2017" saveName="Unnamed save">
   <folder name="file:///C:/Users/AD/Downloads" />
   <folder name="file:///C:/Users/AD/Desktop/t" />
   <folder name="file:///C:/ProgramData/OFBM" />
  </OFBM>
  <OFBM time="10:42" date="06.10.2017" saveName="Unnamed save">
   <folder name="file:///C:/Users/AD/Downloads" />
   <folder name="file:///C:/Users/AD/Desktop/t" />
   <folder name="file:///C:/ProgramData/OFBM" />
  </OFBM>
</root>

Charles Mager · Accepted Answer · 2017-10-06 08:28:18Z

2

There are a couple of problems:

XElement root = XElement.Load(pathToXml);

Here, root is OFBM. So when you query root.Elements(), the elements returned will be the children of OFBM, i.e. 3 folder elements. This means your query root.Elements("OFBM") will never return any elements.

Secondly, ReplaceWith will replace the entire element with some text. You want to set the saveName attribute value.

This code would work:

var root = XElement.Load("path/to/file.xml");

if ((string) root.Attribute("time") == "10:32" && 
    (string) root.Attribute("date") == "06.10.2017")
{
    root.SetAttributeValue("saveName", "new folder name");
}

root.Save("path/to/file.xml");

answered Oct 6, 2017 at 8:28

Charles Mager

26.3k2 gold badges41 silver badges52 bronze badges

5 Comments

Alex Over a year ago

For some reason the root.Attribute("time") is empty. Any idea why? While debugging I see that root isn't empty. Root has: - root {<root saveName="Test4"> <OFBM time="10:20" date="06.10.2017" saveName="Unnamed save">

Alex Over a year ago

Okay, noticed that OFBM isn't the root element it's a child of it, so I need to change the attribute of a child :D

Charles Mager Over a year ago

@AleksD in which case, the XML in your question is not representative of your problem.

Alex Over a year ago

Totally my fault for misrepresenting the actual XML file. Sorry.

Charles Mager Over a year ago

@AleksD no problem, seems you've got it sorted now at least!

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