Question

I really need to be somewhere else this morning. So, I have decided to post a performance question here instead.

The code below works but it calls Load and Save method multiple times. This seems far from efficient. Please could someone provide the code so far the load and save lines occur outside the loop. I wish to call load and save only once.

Thanks chaps 🙂

 public void RemoveNodes(IList<String> removeItems)

    {

        foreach (String removeItem in removeItems)

        {

            XDocument document = XDocument.Load(fullFilePath);

            var results = from item in document.Descendants(elementName)

                          let attr = item.Attribute(attributeName)

                          where attr != null && attr.Value == removeItem.ToString()

                          select item;

            results.ToList().ForEach(item => item.Remove());

            document.Save(fullFilePath);

        }

    }

Answer 1

You’ve already given the answer yourself – just move the Load and Save calls outside the loop. It’s not clear to me where you were having problems implementing that yourself…

You can make your query slightly simpler too though:

XDocument document = XDocument.Load(fullFilePath);
foreach (String removeItem in removeItems)
{
    var results = from item in document.Descendants(elementName)
                  where (string) item.Attribute(attributeName) == removeItem
                  select item;
    results.ToList().ForEach(item => item.Remove());
}
document.Save(fullFilePath);

This uses the fact that the conversion from XAttribute to string returns null if the attribute reference itself is null.

You don’t even need to use a query expression:

var results = document.Descendants(elementName)
          .Where(item => (string) item.Attribute(attributeName) == removeItem);