Skip to main content

Escaping DWT ${ } Syntax

A while back, I was writing about the Dreamweaver Double Lookup technique for Tridion templating.

I was however struggling with escaping the DWT notation, notably with JSTL Expression Language syntax. The EL syntax is the same with DWT's for outputting variables and expressions: ${ expression }

I used to output EL expressions as $[ expression ] and then have a TBB to replace the square brackets with curly braces.

Finally, I found out today not one, but two ways to escape the DWT syntax ${}. Both following expressions output ${'Hello, world'}
  • ${'$'}{'Hello, world'}
  • @@'$'@@{'Hello, world'}
The trick in both cases is to escape the output of the dollar symbol ($) by using it as String parameter in the surrounding @@ @@ or ${ }. What follows is the normal unescaped {'Hello, world'} output.

Now you know... :)

But, wait... we are not there yet! This approach above, only works from a Dynamic CT or a Page Template. The embedded CT will not work as expected. The reason is the two DWT TBBs that get executed with embedded CPs: one for the CT itself and the second for the PT that outputs the Component Presentation.

An embedded CT that contains the code ${'$'}{'Hello, world'} produces DWT output ${'Hello, world'} and when the PT executes, it generates the final output  Hello, world

So the solution is to encode the string twice (you're heading now for a headache) :)

The embedded CT DWT: ${'$'}{'${'$'}'}{'Hello, world'} - I'll explain below
The CT output (i.e. input for PT): ${'$'}{'Hello, world'} - expression explained above
The PT output: ${'Hello, world'} - the desired JSTL EL output

A similar notation for the CT is: @@'$'@@{'@@'$'@@'}{'Hello, world'}

The way this works:
  • ${'$'} or @@'$'@@ outputs a dollar sign ($);
  • {' outputs normally a open curly brace and an apostrophe;
  • ${'$'} or @@'$'@@ outputs a dollar sign ($) again;
  • '} outputs normally an apostrophe and a close curly brace;
  • {'Hello, world'} outputs normally as-is;


Popular posts from this blog

Content Delivery Monitoring in AWS with CloudWatch

This post describes a way of monitoring a Tridion 9 combined Deployer by sending the health checks into a custom metric in CloudWatch in AWS. The same approach can also be used for other Content Delivery services. Once the metric is available in CloudWatch, we can create alarms in case the service errors out or becomes unresponsive. The overall architecture is as follows: Content Delivery service sends heartbeat (or exposes HTTP endpoint) for monitoring Monitoring Agent checks heartbeat (or HTTP health check) regularly and stores health state AWS lambda function: runs regularly reads the health state from Monitoring Agent pushes custom metrics into CloudWatch I am running the Deployer ( installation docs ) and Monitoring Agent ( installation docs ) on a t2.medium EC2 instance running CentOS on which I also installed the Systems Manager Agent (SSM Agent) ( installation docs ). In my case I have a combined Deployer that I want to monitor. This consists of an Endpoint and a

Running sp_updatestats on AWS RDS database

Part of the maintenance tasks that I perform on a MSSQL Content Manager database is to run stored procedure sp_updatestats . exec sp_updatestats However, that is not supported on an AWS RDS instance. The error message below indicates that only the sa  account can perform this: Msg 15247 , Level 16 , State 1 , Procedure sp_updatestats, Line 15 [Batch Start Line 0 ] User does not have permission to perform this action. Instead there are several posts that suggest using UPDATE STATISTICS instead: I stumbled upon the following post from 2008 (!!!), , which describes a way to wrap the call to sp_updatestats and execute it under a different user: create procedure dbo.sp_updstats with execute as 'dbo' as

Event System to Create Mapped Structure Groups for Binary Publish

As a continuation of last week's Publish Binaries to Mapped Structure Group , this week's TBB is in fact the Event System part of that solution. Make sure you do check out the previous post first, which explains why and what this Event System does. To reiterate, the Event System intercepts a Multimedia Component save, take its Folder path and create a 1-to-1 mapping of Structure Groups. The original code was written, again, by my colleague Eric Huiza : [ TcmExtension ( "MyEvents" )] public class EventsManager  : TcmExtension {     private Configuration configuration;     private readonly Regex SAFE_DIRNAME_REGEX = new Regex ( @"[\W_]+" );     public EventsManager() {         ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap ();         fileMap.ExeConfigFilename = Path .GetDirectoryName( Assembly .GetExecutingAssembly().Location) + "\\EventSystem.config" ;         configuration = ConfigurationManager