Question

I am working on a Window Phone app were I need to use xpath with linq. Unfortunately xpath is not currently supported. I have an xml file that I recursively drill down as the user select nodes. The node()/@title is loaded into a listbox. The user selects and so-on. I normally would dynamically build the xpath predicates.

For example:

<cfr>
<chapter title="CHAPTER VI" volume="6">
    <subchapter title="SUBCHAPTER A" volume="6">
        <part number="600" title="PART 600">
            <subpart number="Subpart A" part="PART 600" title="Subpart A Farm Credit Administration">
                <section number="600.1" title="The Farm Credit Act." part="PART 600" link="12CFR600.1" type="cfr"/>
                <section number="600.2" title="Farm Credit Administration." part="PART 600" link="12CFR600.2" type="cfr"/>
            </subpart>
        </part>
        <part number="601" title="PART 601">
            <section number="601.1" title="The Credit Act." part="PART 601" link="12CFR6001.1" type="cfr"/>
        </part>
    </subchapter>
    <part>......</part>
</chapter>
</cfr>   

In xpath I would use:

/node()/node()/node()/node()[@title='PART 601']/node()[@title='The Music Act.']/@title

I keep track of how deep the user has clicked and which index. I would build the xpath predicate like so in c#:

 private String XpathBuilder(bool isParentNode)
    {
        int nCount = AcmSinglton.NodeCount;
        StringBuilder nodeStr = new StringBuilder();
        nodeStr.Append("/node()/node()");

        for (int i = 0; i < nCount; i++)
        {
            if (i != 0)
            {
                nodeStr.Append("[@title = '" + AcmSinglton.TitlePredicatesArrayList.get(i - 1).toString() + "']/node()");
            }
            else
            {
                nodeStr.Append("/node()");
            }
        }
        return nodeStr.ToString();
    }

So I am looking for idea to dynamically build predicates using linq-to-xml.

Here is what I have so far:

 XDocument xml = XDocument.Load(String.Format("Resourses/c{0}x{1}.xml", this.CFRTitle, this.Volume));               
            var nodes = from x in xml.Elements().ElementAt(nodeDepth).Elements()
                        select new Menus.Chapter
                        {
                           Title = x.Attribute("title").Value
                        };

            this.MainListBox.ItemsSource = nodes.ToList();

Answer 1

Something like this should work:

var currentLevelElements = doc.Root.Elements();
int depth = 0;
while (currentLevelElements != null && depth < nodeDepth)
{
    currentLevelElements = currentLevelElements.Elements()
                                               .Where( x=> (string) x.Attribute("title") == AcmSinglton.GetTitle(depth));
    depth++;
}
var nodes = from x in currentLevelElements select new Menus.Chapter
                    {
                       Title = x.Attribute("title").Value
                    };

It seems awkward to query a Singleton for the title information – this is a dependency that should be passed into your method directly.