Working With Specific XML structure

Question

I am trying to get some data from an XML document. I have no control over the schema. If it were up to me I would have chosen another schema. I am using C#'s XPATH library to get the data.

XML DOC

<Journals>
    <name>Title of Journal</name>
    <totalvolume>2</totalvolume>
    <JournalList>
        <Volume no="1">
            <Journal>
                <issue>01</issue>
                <Title>Title 1</Title>
                <date>1997-03-10</date>
                <link>www.somelink.com</link>
            </Journal>
            <Journal>
                <issue>02</issue>
                <Title>Title 3</Title>
                <date>1997-03-17</date>
                <link>www.somelink.com</link>
            </Journal>
        </Volume>
        <Volume no="2">
            <Journal>
                <issue>01</issue>
                <Title>Title 1</Title>
                <date>1999-01-01</date>
                <link>www.somelink.com</link>
            </Journal>
            <Journal>
                <issue>01</issue>
                <Title>Title 2</Title>
                <date>1999-01-08</date>
                <link>www.somelink.com</link>
            </Journal>
        </Volume>
    </JournalList>
 </Journals>

I am trying to get all the data in the Volume 2 node. Here is what I tried so far:

C# Code:

protected void loadXML(string url)
{
    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.Load(url);

    string strQuery = "Volume[@no='2']";

    XmlElement nodeList = xmlDoc.DocumentElement;
    XmlNodeList JournalList = nodeList.SelectNodes(strQuery);

    foreach (XmlElement Journal in JournalList)
    {
        XmlElement temp = Journal;
    }
}

It seems there are no nodes in JournalList. Anyone? Thanks in advance/

Note that using an XDocument is easier than an XmlDocument. With XmlDocument you are basically limited to using XPath queries, whereas with XDocument you can use LINQ. — slugster
– slugster, Commented Jan 4, 2015 at 4:40
@slugster LINQ is nice and all, but it's not inherently better. XPath can handle this situation (and many much more complex ones) with ease. — Tomalak
– Tomalak, Commented Jan 4, 2015 at 7:17

Grant Winney · Accepted Answer · 2015-01-04 05:49:15Z

1

Your code is looking for "Volume" nodes directly under the "Journals" node

Change this:

string strQuery = "Volume[@no='2']";

To this, in order to look for "Volume" nodes under the "JournalList" node:

string strQuery = "JournalList/Volume[@no='2']";

Also, there's a couple typos in your XML:

</Volume no="2">  ->  <Volume no="2">   // no open tag found

</Journal>        ->  </Journals>       // expecting end tag </Journals>

From your comment below:

how would I go about access each journal? for example. I want irrate through each "journal" and get the title of the journal?

In order to do that, you could modify your code slightly:

var nodeList = xmlDoc.DocumentElement;
var volume = nodeList.SelectSingleNode(strQuery);
foreach (XmlElement journal in volume.SelectNodes("Journal"))
{
    var title = journal.GetElementsByTagName("Title")[0].InnerText;
}

edited Jan 4, 2015 at 5:49

answered Jan 4, 2015 at 4:14

Grant Winney

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3 Comments

Peter Sun Over a year ago

thanks for response, but i have a questions. how would I go about access each journal? for example. I want irrate through each "journal" and get each journal title within Volume 2? I want to use a foreach statement, but it seems i am only i am grabbed Volume 2. How would I go about getting the nodes within it?

Tomalak Over a year ago

@Grant I believe your second code sample contains a mistake. Shouldn't you iterate over xmlDoc.SelectNodes("//JournalList/Volume[@no=2]") instead of over volume.SelectNodes("Journal")?

Tomalak Over a year ago

Ah, I see. It's implemented a bit more complicated than it needs to be, but it would work. xmlDoc.SelectNodes("//JournalList/Volume[@no = 2]/Journal") would select the wanted nodes straight-away, saving a few lines.

ocuenca · Accepted Answer · 2015-01-04 04:27:35Z

0

Also you can use Linq to XML:

using System.Xml.Linq;
//...
string path="Path of your xml file"
XDocument doc = XDocument.Load(path);
var volume2= doc.Descendants("Volume").FirstOrDefault(e => e.Attribute("no").Value == "2");

answered Jan 4, 2015 at 4:27

ocuenca

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1 Comment

Tomalak Over a year ago

doc.Descendants("Volume").FirstOrDefault(e => e.Attribute("no").Value == "2") - 77 characters. doc.SelectNodes("//Volume[@no=2]") - 34 characters, and easier to read.

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