Question

I have an XML File resembling the following:

<root>
   <parent label="parent1">
      <child label="child1">
         <element1>data</element1>
         <element2>data</element2>
         ...
         <grandchildren>
             <grandchild label="grandchild1">
                 <elementa>data</elementa>
                 <elementb>data</elementb>
             </grandchild>
         </grandchildren>
      </child>
      <child label="child2">
         <element1>data</element1>
         <element2>data</element2>
         ...
         <grandchildren>
             <grandchild label="grandchild2">
                 <elementa>data</elementa>
                 <elementb>data</elementb>
             </grandchild>
         </grandchildren>
      </child>
   </parent>
</root>

The XML serves as data source for a treeview. Users can select a parent there, and the properties of the parent will be displayed in a listview (which uses a LINQdataview as data source). I’m pulling the data out using a linq query. However, I would like to display the GrandChildren in a seperate control (a Telerik grid).

I created a new XMLDataSource in the listview cell, which will pull its data from the child’s xPAth (something I add in the code, see below), as well as the intended grid. The grid is set to have the XMLDataSource as its DataSourceID.

Here’s the code I use to pull the data in the Selecting event:

protected void listsSource_Selecting(object sender, LinqDataSourceSelectEventArgs e) {
    XElement rootElement = XElement.Load(MapPath(TreeSource.DataFile));

    parentElement = rootElement.XPathSelectElement("//parent[@label='" + tvw.SelectedNode.Text + "']");

    var query = from element in parentElement.DescendantsAndSelf("child")
        select new {
            element1 = element.Element("element1").Value,
            element2 = element.Element("element1").Value,                               
            xPathAddress = "//parent[@label='" + tvw.SelectedNode.Text + "']",
            grandchildrenXPath = "//parent[@label='" + tvwMaterials.SelectedNode.Text + "']" + "/grandchildren"
    };

    e.Result = query;
}

Here’s the code from the ASPX:

<td rowspan="7" style="border-style: solid; border-width: thin" align="center">
    <telerik:RadGrid ID="gridRelatives" runat="server" DataSourceID="XmlRelatives" >
                                </telerik:RadGrid>
    <asp:XmlDataSource ID="XmlRelatives" runat="server"
        DataFile="~/XML/Data/relatives.xml" xPath='<%# Eval("grandchildrenPath") %>'></asp:XmlDataSource>
</td>

However, this leads to a “Cannot find any bindable properties in an item from the datasource” error, and I am guessing that this is because of attempting to load the XML dynamically, causing it not to trigger when the ListSource selecting event fires.

Should I instead load the data in a seperate query statement, or am I overlooking something fairly simple?

Any help would be greatly appreciated, as this has had me stumped for a while now 🙂

Thanks.

Update:

Tried adding a second linq query to the selecting code, in an attempt to set the XPath part of a second XMLDataSource, but this gives me another error. Code:

var query2 = from element in parentElement.DescendantsAndSelf("child")
    select new {
        grandchildrenXPath = "//parent[@label='" + tvw.SelectedNode.Text + "']" + "/grandchildren"
    };
myThickness.XPath = query2.ToString();
myThickness.DataBind();

Error:

‘System.Linq.Enumerable+WhereSelectEnumerableIterator2[System.Xml.Linq.XElement,<>f__AnonymousType31[System.String]]’ has an invalid token.

Commenting the new lines has things working again.

I’m still hoping to find a solution for this. I imagined that building the xPath dynamically would be a great way to accomplish this, but obviously that is a no-go. What am I not seeing here?

Answer 1

I ended up figuring out a workaround by adding a new XMLDataSource and loading that within the listsSource_Selecting event.

I tried doing this before, but placed the code above the LINQ query that feeds the ListView this time. That does not throw any errors anymore.