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Passing PageUri to a DCP for Dynamic Linking


We should all know by now that passing an empty (aka Null TcmUri) as PageUri when resolving a Component Link is very bad practice. The reason -- this kind of link resolving is not cached. So, in case you are using a Content Delivery DB, you will make a trip to the DB for every single Component Link resolving.

I have written an older article available here on SDLTridionWorld, about solving these issues, but that's about old school templating. This post presents the mechanism to use when writing Compound Templates.

So, I have a DWT TBB that generates some output for an RTF field. Something like @@Component.Fields.Paragraph@@. I have some ComponentLinks in the RTF field.

The templates runs on a DCP and it generates a TCDL link like this:
<tcdl:Link type="Component" origin="tcm:0-0-0" destination="tcm:37-968" templateURI="tcm:0-0-0" linkAttributes="" textOnFail="true" addAnchor="false" variantId="">Read more</tcdl:Link>.

The problem is the origin is tcm:0-0-0. I want to have my own value/variable here. In JSP, I can use a JSTL variable like this:
<tridion:ComponentLink pageURI="${PageUri}" componentURI="tcm:37-969" templateURI="tcm:0-0-0" addAnchor="false" linkText="Read more" linkAttributes="" textOnFail="true"/>

Where ${PageUri} is some JSTL variable set with the following code in the ‘calling’ JSP:
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<c:set var="PageUri" value="tcm:37-986-64" scope="request"/>

But anyway, the problem for me is how to get that PageURI attribute (or origin) assigned to my actual value?

The solution I used in this case is the following:
  • C# TBB that parses the <tcdl:Link origin="tcm:0-0-0"… and replaces the NullUri with ${PageUri}
    • Only does that for ‘Publish’, not for preview;
  • Add this TBB at the bottom of the Dynamic CT (after DefaultFinishActions, or after LinkResolver);
Code sample:

private static Regex ComponentLinkRegex = new Regex(@"<tcdl:Link type=""Component"" origin=""tcm:0-0-0""");

public void Transform(Engine engine, Package package)
{
    if (!engine.RenderMode.Equals(RenderMode.Publish))
    {
        Logger.Debug("Render mode not Publish. Do not perform any replacements");
        return;
    }

    Item OutputItem = package.GetByName(Package.OutputName);
    String OutputText = OutputItem.GetAsString();

    // Component Links with null origin
    Match match = ComponentLinkRegex.Match(OutputText);
    while (match.Success)
    {
        String ReplaceLink = match.Value.Replace("tcm:0-0-0", inputParam);
        // inputParam is the value to replace with. e.g. "${PageUri}"
        OutputText = OutputText.Replace(match.Value, ReplaceLink);
        match = match.NextMatch();
    }

    OutputItem.SetAsString(OutputText);
}



Comments

Nuno said…
Awesome, I needed this code just now. :)

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