Ordering XElements

Question

I have the following XML Document (that can be redesigned if necessary) that stores records and errors.

<MYROOT>  
  <RECORDS>
    <RECORD>
      <DATETIME>11/03/2010 14:12:41</DATETIME>
      <DOCUMENTID>1</DOCUMENTID>
    </RECORD>
    <RECORD>
      <DATETIME>11/03/2010 14:12:44</DATETIME>
      <DOCUMENTID>2</DOCUMENTID>
    </RECORD>
    <RECORD>
      <DATETIME>11/03/2010 14:12:45</DATETIME>
      <DOCUMENTID>3</DOCUMENTID>
    </RECORD>
  </RECORDS>
  <ERRORS>
    <ERROR TYPE="ERR">
      <DATETIME>11/03/2010 14:12:41</DATETIME>
      <DETAIL>There has been a error on page 1</DETAIL>
    </ERROR>
    <ERROR TYPE="ERR">
      <DATETIME>11/03/2010 14:13:03</DATETIME>
      <DETAIL>There has been a error on page 101</DETAIL>
    </ERROR>
    <ERROR TYPE="SEQ">
      <DATETIME>11/03/2010 14:13:03</DATETIME>
      <DETAIL>Sequence Error, expected Sequence No. 101 Read 1</DETAIL>
    </ERROR>
  </ERRORS>
</MYROOT>

I want to output the records and errors but obviously have to sort them by date so they appear in order.

How can I sort them by date, get a collection of XElements and then just do a foreach loop over them?

Answer 1

var elements = doc.Descendants("RECORD").Concat(doc.Descendants("ERROR")).
    OrderBy(x => DateTime.Parse(x.Element("DATETIME").Value));
foreach (XElement element in elements)
{
    // do something interesting with element
}

Answer 2

XDocument xml = System.Xml.Linq.XDocument.Parse(YOUR_XML);
IEnumerable<XElement> records = xml.Root.Element("RECORDS").Elements();
IEnumerable<XElement> errors = xml.Root.Element("ERRORS").Elements();

IEnumerable<XElement> elements = from el in records.Concat(errors)
                                 orderby DateTime.Parse(el.Element("DATETIME").Value)
                                  select el;

foreach (XElement el in elements)
{
    // do something.
}