DTML Basics (part 2) - If Only...
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The first - and simplest - decision-making routine is the "if" statement, which generally looks like this:

<dtml-if id> 

do this!

</dtml-if>

The "condition" here refers to a conditional expression, which evaluates to either true or false.

Let's look at a piece of code to understand this better. Here's a DTML Method named "ifOnly", created in the same "DTML Basics" folder I used last time.

<dtml-if id> 

<p>Variable "id" exists and has the value <dtml-var id>.</p> </dtml-if>



<dtml-if myName>

<p>Variable "myName" exists and has the value "<dtml-var myName>".</p>

</dtml-if>

Now, when you view the output of this Method, you should see the following:

Variable "id" exists and has the value DTML Basics.

If you take a close look at the code above, you'll see that it includes two "if" statements; however, only one is displayed in the output. This is because the first statement evaluated to a true value, because the variable "id" exists and has a value (the name of the container within which the DTML Method is stored). However, the second DTML variable "myName" does not exist. As a result, the corresponding "if" statement evaluates as false, and so, the text enclosed within the <dtml-if> block is not displayed.

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