c# - XmlReader skips elements

Question

I have the following code to stream from a large XML file. However, some <Campaign/> elements are skipped. Any reason for this?

public static IEnumerable<XElement> StreamItem(string uri)
{
    using (var reader = XmlReader.Create(uri))
    {
        XElement campaign = null;

        reader.MoveToContent();

        // Loop through <Campaign /> elements
        while (reader.Read())
        {
            if (reader.NodeType == XmlNodeType.Element && reader.Name == "Campaign")
            {
                campaign = XNode.ReadFrom(reader) as XElement;
                yield return campaign;
            }
        }
    }
}

Update:

The XML file is well-formed and has the following structure.

<CRoot>
    <Campaign CampaignID="136">
        <!-- other nested elements -->
    </Campaign>
    <Campaign CampaignID="137">
        <!-- other nested elements -->
    </Campaign>
    <!-- etc -->
</CRoot>

Answer 1

XNode.ReadFrom is advancing your reader to the next Campaign open tag (if there is no whitespace between them) then reader.Read will advance to the inner text of that tag. You need to skip the reader.Read after a XNode.ReadFrom like this.

public static IEnumerable<XElement> StreamItem(string uri)
{
    using (var reader = XmlReader.Create(uri))
    {
        XElement campaign = null;

        reader.MoveToContent();

        // Loop through <Campaign /> elements
        reader.Read();
        while (!reader.EOF)
        {
            if (reader.NodeType == XmlNodeType.Element && reader.Name == "Campaign")
            {
                campaign = XNode.ReadFrom(reader) as XElement;
                yield return campaign;
            }
            else
            {
                reader.Read();
            }
        }
    }
}

Note that if you have Campaign nodes nested in other Campaign nodes those will end up as part of the parent node and not be pulled out as separate nodes.