Problem reading an XML file in ASP.NET

Question

I'm using a simple XmlReader on the following file structure:

<application>
    <nodetitle permission="perm1">Some Dept</nodetitle>
    <project>Project A</project>
    <links>
        <link>
            <pagename>page1.aspx</pagename>
        </link>
        <link>
            <pagename permission="perm2">page2.aspx</pagename>
        </link>
        <link>
            <pagename>page3.aspx</pagename>
        </link>
    </links>
</application>

I'm rusty on the XML API and my problem is reading the sibling <link> elements in a single pass - my instinct is to look to create some kind of inner loop?

while (reader.Read())
{
    ...

    if ((reader.NodeType == XmlNodeType.Element) && (reader.Name == "links"))
    {
        // read all <link> elements in a single pass
    }
    ...
}

UPDATE - 06-25-2011

I'm going to try and be a little more specific. I'm not using XPath. Using either the XmlReader or Linq to Xml (am totally unfamiliar with this), I want a way to extract the link elements and attributes and check their values.

Is there any reason you don't want to just use xpath to select the nodes you want? Using an XmlReader seems much more difficult. — rsbarro, Jun 24 '11 at 21:22
I guess not, just never used it before. I want to be able to extract all info (atts & values) for each link before moving on to the next iteration of the main while loop - would welcome a code sample :) — IrishChieftain, Jun 24 '11 at 21:26
I had a look at Api and found method to read subtree, method is reader.ReadSubtree. It returns you an instance of XmlReader object — Kunal, Jun 24 '11 at 21:54

score 4 · Answer 1 · answered Jun 24 '11 at 21:51

4

LINQ to XML makes this stuff crazy easy sauce:

XDocument doc = XDocument.Parse("xml here or use .Load()");
var links = doc.Descendants("link");

You can extend off from here reading attributes (XAttribute) off the XNode individually or again using LINQ to obtain all of the attributes for all nodes etc etc.

answered Jun 24 '11 at 21:51

Darren Lewis

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Have never used LINQ to XML, is it possible to query without using an XDocument? Looking for a link relevant to this scenario... – IrishChieftain Jun 24 '11 at 23:42
You can start at the XNode level using the static XNode.ReadFrom method which takes your XmlReader as a param and returns the XML fragment as an XNode. If you don't have it already I'd highly recommend downloading LINQPAD (http://www.linqpad.com), loading in your XML and exploring the API. – Darren Lewis Jun 25 '11 at 10:14
Daz, can you give me the syntax or a doc link, for digging into the elements and attributes? Thanks :) – IrishChieftain Jun 25 '11 at 16:45

kprobst · Accepted Answer · 2011-06-24T22:14:11.277

Well if you use an XML doc you could do something like this:

XmlNodeList nodeList = xmlDocument
    .DocumentElement.SelectNodes("//application/links/link");

foreach (XmlNode node in nodeList) {
    ...
}

In the loop just get the inner <pageName> element and read the attributes and/or text.

That said, XPath is much easier, faster and memory efficient than a reader or a full Xml doc. Linq2XML is also really good to work with, since you can use Linq syntax on the parse tree.

Edit:

I felt kind of dirty for mentioning XmlDocument so I created a simple Linq2Xml example to show how easy this is even omitting any Linq syntax, just in case you want to go for it:

string path = @"C:\path\to\my\xmlfile.xml";
XDocument doc = XDocument.Load(path, LoadOptions.None);

var nodes = doc.Root.Element("links").Elements("link");
foreach (var node in nodes) {
    var pageNameElement = node.Element("pagename");
    XAttribute permAttribute = pageNameElement.Attribute("permission");
    string permission = "";
    if (permAttribute != null)
        permission = permAttribute.Value;
    string text = pageNameElement.Value;
    // Do something with the values...
}

You can of course initialize the XDocument with a stream, if that's what you already have. Hope this helps :)

Working through this now, feel free to offer any Linq syntax :) — IrishChieftain, Jun 25 '11 at 15:18

score 1 · Answer 3 · answered Jun 24 '11 at 21:40

Although i wouldnt prefer XmlReader over LINQ or XmlDocument, this should help u working with xmlReader(scroll down) http://vbdotnetforum.com/index.php?/topic/493-creating-an-xml-reader/

--

U might want to use LINQ, it shouldnt be hard to understand.. Here is a starter http://www.developingfor.net/c-30/upgrade-your-c-skills-part-5-linq-to-xml.html

Problem reading an XML file in ASP.NET

3 Answers3