Question

I’m seeing strange behavior when I try to parse XML using the LINQ XmlReader class. Test case below: it looks like whether I use (XElement)XNode.ReadFrom(xmlReader) or one of the Read() methods on XmlReader, it misses the second bar elements in the input XML. If any whitespace is added between the </bar> and <bar> then it will parse the second bar element correctly.

Does anyone have an idea of why the input stream gets messed up and how to get around this problem?

    [Test]
    [Explicit]
    public void ShouldParseCorrectNumberOfElements()
    {
        var xml = @"<foo><bar>wtf</bar><bar>wtf2</bar></foo>";
        XmlReader xmlReader = XmlReader.Create(new MemoryStream(Encoding.UTF8.GetBytes(xml)));

        int count = 0;
        xmlReader.MoveToContent();
        while (xmlReader.Read())
        {
            if (xmlReader.NodeType == XmlNodeType.Element && xmlReader.Name == "bar")
            {
                var element = xmlReader.ReadOuterXml();
                Console.WriteLine("just got an " + element);
                count++;
            }
        }
        Assert.AreEqual(2, count);
    }

Answer 1

You’re calling ReadOuterXml, which will consume the element and place the “cursor” just before the next element. You’re then calling Read again, which moves the cursor on (e.g. to the text node within the element).

Here’s an alternative to your loop:

while (!xmlReader.EOF)
{
    Console.WriteLine(xmlReader.NodeType);
    if (xmlReader.NodeType == XmlNodeType.Element && xmlReader.Name == "bar")
    {
        var element = xmlReader.ReadOuterXml();
        Console.WriteLine("just got an " + element);
        count++;                
    }
    else
    {
        xmlReader.Read();
    }
}