Generating Outputs from MySQL with Static Members and Methods in PHP 5 - Creating the ResultToString, ResultToXML and ResultToArray classes
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As the title of this section indicates, my intention consists basically of building up three different classes, where each of them will be tasked with taking up a given MySQL result set. They will then apply to it the proper conversion process; that is, they will turn the data set rows into plain strings, XML data and an associative array respectively. Finally, they will return the results to calling code.
All right, after explaining the main purpose of each one of the classes that I plan to create, it’s time to see how they look, right? I have listed their source code below, so check them out:
// define 'ResultToString' class
class ResultToString{
private $result;
public function
__construct(Result $result){
$this->result=$result;
}
// fetch result set as plain text
public function fetch(){
$str='';
while($row=$this->result->fetchRow()){
foreach($row as $key=>$value){
$str.='['.$key.']='.$value."n";
}
$str.='--------------------------'."n";
}
return $str;
}
}
// define 'ResultToXML' class
class ResultToXML{
private $result;
public function
__construct(Result $result){
$this->result=$result;
}
// fetch result set as XML
public function fetch(){
$xml='<?xml
version="1.0"
encoding="iso-8859-1"?>'."n".'<data>'."n";
while($row=$this->result->fetchRow()){
$xml.='<row>'."n";
foreach($row as $key=>$value){
$xml.='<'.$key.'>'.$value.'</'.$key.'>'."n";
}
$xml.='</row>'."n";
}
$xml.='</data>'."n";
return $xml;
}
}
// define 'ResultToArray' class
class ResultToArray{
private $result;
public function
__construct(Result $result){
$this->result=$result;
}
// fetch result set as array
public function fetch(){
$data=array();
while($row=$this->result->fetchRow()){
$data[]=$row;
}
return $data;
}
}
As you’ll realize, the logic of the three classes shown above is fairly easy to understand. Essentially, each of them will accept an object of type “Result” inputted via the corresponding constructor. The object will be used from inside the class to convert a given MySQL result set to the corresponding format, that is plain strings, XML or an associative array.
With reference to the conversion process in question, this will be performed in all the previously defined classes by using their “fetch()” method, which obviously implements a different logic in accordance with the type of data that must be returned to calling code. Simple and efficient, isn’t it?
Okay, at this point I defined the pair of MySQL processing classes that you saw in a previous section, as well as the three that were created a few lines above and are handy for generating several outputs from a specific result set. However, until now I've not given you a single clue about how and why we will include static methods within the classes just defined. So, where will they be coded?
Fortunately, I have a good answer for that question. Since my primary objective is to generate disparate data formats from a single MySQL result set, the next step that I’m going to take will consist of creating an additional class, which will be capable of returning distinct data set processor objects to produce the range of outputs that I mentioned before.
How will this be done? Yep, you guessed right. The entire process for returning result set processor objects to calling code will be handled by a static method! After all, we’re not far from reaching our goal, but this requires you to jump straight into the next section and continue reading. Thus, go ahead. I’ll be there, waiting for you.
Next: Defining the ResultProcessorFactory class >>
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