Update XML file from List

Question

I have a XML file containing records like -

<?xml version="1.0" encoding="utf-8"?>
<ArrayOfCLocation xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <CLocation>
    <CId>5726</CId>
    <Long>0</Long>
    <Lat>0</Lat>
    <Status>Pending</Status>
  </CLocation>
  <CLocation>
    <CId>5736</CId>
    <Long>0</Long>
    <Lat>0</Lat>
    <Status>Processed</Status>        
  </CLocation>
</ArrayOfCLocation>

I take these records into List as -

XDocument xDocument = XDocument.Load(filePath); 
List<T> list = xDocument.Descendants("CLocation")
     .Select(c => (new T()
     {
         CId = Convert.ToInt32(c.Descendants("CId").FirstOrDefault().Value),
         Lat = Convert.ToDouble(c.Descendants("Lat").FirstOrDefault().Value),
         Long = Convert.ToDouble(c.Descendants("Long").FirstOrDefault().Value),
         Status = (Status)Enum.Parse(typeof(Status), c.Descendants("Status").FirstOrDefault().Value)
     }))
     .Where(c => c.Status == Status.Pending)
     .Take(listCount)
     .ToList();

Now, I update T objects(setting their Lat/Log fields) in above collection and after processing these objects, I want to update these records back into XML file.

Can anyone please guide me for a efficient solution for how can I update these objects back into XML file.

How much is efficiency important to you? Are you going to be processing huge XML files? Or do you mean just readable and succinct code? — svick, Dec 02 '11 at 00:36
well, I actually meant all these :-) Although right now XML file will be having 500 such CLocation elements, but may jump to 1000s in future. And, yes succinct code is always a plus :-) — inutan, Dec 02 '11 at 00:42

score 4 · Answer 1 · answered Dec 02 '11 at 00:51

You could do something like this:

foreach (var location in list)
{
    var elem = xDocument.Root.Elements()
                        .Single(e => (int)e.Element("CId") == location.CId);
    elem.Element("Long").ReplaceNodes(location.Long);
    elem.Element("Lat").ReplaceNodes(location.Lat);
}

You can then save the modified xDocument back to a file, or whatever.

If you find this is not efficient enough, there are several ways to speed things up. For example create a Dictionary of elements by CId, so that the whole document is not searched every time.

But if you have huge files, loading them whole into memory might not be possible or a good idea. Using XmlReader and XmlWriter will work for files of any size, but they are not as easy to use.

Another option to consider is XML serialization. It's made specifically for converting XML into your objects and back.

Also, the code you have could be simplified quite a lot, and in the process made faster:

xDocument.Root.Elements("CLocation")
     .Select(c => new Location
                  {
                      CId = (int)c.Element("CId"),
                      Lat = (double)c.Element("Lat"),
                      Long = (double)c.Element("Long"),
                      Status = (Status)Enum.Parse(typeof(Status), c.Element("Status").Value)
                  })

Update XML file from List

1 Answers1