Essentially, what I plan to do here is generate different output formats, based on the same MySQL result set, by using several decorator classes. However, I have to admit a nearly identical result might be achieved by aggregating some additional methods to the “Result” class that you saw before. Why not do it that way?

Well, I have a good reason for not doing this. I want to keep the scope of the “Result” class limited to handling result sets, without contaminating its source code with methods that deal with formatting them.

As you can see, here the reward is double: you work with completely independent objects, while using decorator classes to apply specific formats to MySQL result sets. Sounds good, doesn't it?

Having justified the real need for creating decorator classes, I’ll show you the first one, which I call “ResultDecorator.” Its definition is as follows:

class ResultDecorator{
    private $resultObj;
    public $resultSet;
    // pass in 'Result' object to the constructor
    public function __construct(Result $resultObj){
        $this->resultObj=$resultObj;
        // get result set without modifying the original object
        $this->resetResult();
    }
    private function resetResult(){
        $this->resultSet=$this->resultObj->getResult();
    }
}

Regarding the brand new class listed above, you’ll see that it takes up an object of type “Result” and assigns it as a class property. It additionally uses its “resetResult()” method to get a result set, after running a SELECT query.

So, recapitulating, I created a new class, which takes a result set from the respective “Result” class without modifying its original structure. That’s exactly what a decorator class is about! We’re on the right track now, since from this point onward, building decorator classes that generate different outputs from the same result set is a straightforward process.

After having defined the handy “ResultDecorator” class that you learned before, it’s time to go one step further and start creating the pertinent decorator classes, aimed at rendering different output formats, based on the same MySQL result set.

That’s exactly the subject of the upcoming section, therefore click on the link that appears below and keep on reading.