Implementing custom conditions

Now we know how to parse TypoScript and the only thing we still want to do is to implement support for custom conditions. As stated in a few places the evaluation of a condition is external to TypoScript and all you need to do in order to have an external process deal with conditions is to pass an object as the second parameter to the parse- function. This is done in the code listing below:

class myConditions {
    /**
    * Evaluates, if the condition line was "[TYPO3 IS GREAT]".
    *
    * @param string $conditionLine The condition line
    * @return boolean value
    */
    public function match($conditionLine) {
        if ($conditionLine === '[TYPO3 IS GREAT]') {
            return true;
        }
    }
}
$matchObj = GeneralUtility::makeInstance(\myConditions::class);

$TSparserObject = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\TypoScript\Parser\TypoScriptParser::class);
$TSparserObject->parse($tsString, $matchObj);

debug($TSparserObject->setup);

In this example, we define a very simple class with a match() function inside. This match() function must exist and take a string as its argument. It is expected to return a boolean value. This function should be programmed to evaluate the condition line according to your specifications. Currently, if a condition line contains the value "[TYPO3 IS GREAT]" then the condition will evaluate to true and the subsequent TypoScript will be parsed.

To enable this condition, we simply create an instance of our class and pass it to the TypoScript parser upon callings the parse() method.

Let's test the custom condition class from the code listing above. This is done by parsing this TypoScript code:

someOtherTS = 123

[TYPO3 IS GREAT]

message = Yes
someOtherTS = 987

[ELSE]

message = No

[GLOBAL]

someTotallyOtherTS = 456

With this listing we would expect to get the object path "message" set to "Yes" since the condition line "[TYPO3 IS GREAT]" matches the criteria for what will return true. Let's try:

According to this output it worked!

Let's try to alter line 2 to this:

[TYPO3 IS great]

The parsed result is now:

As you can see the value of "message" is now "No" since the condition returned FALSE. The string "[TYPO3 IS great]" is obviously not the same as "[TYPO3 IS GREAT]"! The value of "someOtherTS" was also changed to "123" which was the value set before the condition and since the condition was not TRUE the overriding of that former value did not happen like in the first case.