逻辑和标记，HTML和PHP

Question

I am learning php. I see that people recommend to separate html and php or logic and markup. But in some specific occasions I am not sure how to do it. For readability and maintainability I try to put all the php in a separate file but now I have to download a title from a database and the only way I see is to put this with the rest of the html and with this html and php mixed. In this specific case, is there a more clean and organized way? is ok to put this peace of php in the "design" file? can or should I put this php code with the rest of the php?

<?php
include("../../externs/includes/connexio.php");

$result = mysqli_query($con, "SELECT * FROM myTable");

while ($row = mysqli_fetch_array($result)) {
    $id = $row["id"];
    $title = $row["title"];
    $subtitle = $row["subtitle"];
?>  

<div class="title" id="<?php echo $id; ?>"><?php echo $title; ?> </div>
<div class="subtitle"><?php echo $subtitle;?> </div>
<br>

<?php 
}//end while items
?>

Answer 1

First of all I would recommend to read about MVC (Model-View-Controller), you can start at this Wikipedia article: http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller

For a simple case as the one fro you question, your solution is, in my opinion, the best. Anything else would be to add unnecessary complexity.

That being said, I will try to use that simple case and offer one possible way to separate logic from presentation with the hope that some basic concepts will become clear from it.

my_controller.php

include("../../externs/includes/connexio.php");

$result = mysqli_query($con, "SELECT * FROM myTable");

$myList = array();
while ($row = mysqli_fetch_array($result)) 
{
    $myList[] = $row;
}

// Now load the view.
include "my_view.php";

my_view.php

<?php foreach ($myList as $row ) : ?>

    <div class="title" id="<?php echo $row['id']; ?>"><?php echo $row['title']; ?></div>
    <div class="subtitle"><?php echo $row['subtitle'];?></div>
    <br>

<?php endforeach; ?>

As you see, I just took your code and separated it in what would be business logic and presentation. The idea here is that data to be presented should be generated outside the View. The View should know nothing about how the data was "generated".

In this example, the View only knows about the variable $myList containing the fields: id, title and subtitle. If you ever change databases or decide to fetch data from a file or even a Web service; you would not have to touch the View at all.

At the same time, the controller doesn't care about how the View shows the data. Regardless of the source: database, Web service, file, etc; it will always produce an array containing at least the fields expected by the View.

The next step to MVC would be to move data manipulation from controller to a model. I won't go there in detail, but this is how the controller would look like:

include "my_model.php";
$myList = fetchData();
include "my_view.php;

The fetchData() function inside the my_model.php file would basically do the same as my_controller.php above.

A very debatable and indeed debated issue is whether having any PHP code inside the View is a good practice. Some argue that other templating languages such as Smarty should be used. My opinion is that changing the syntax by adding another language doesn't change the inevitable fact that you need some logic in the View, otherwise you would be unable to introduce dynamism to your applications.

As you feel more comfortable reading PHP code, you will be able to look into the several frameworks around and see how they do it. One thing they all have in common is that they all have some logic in the presentation layer, whether it is PHP or something else.

Answer 2

Following are the best practices you can follow while mixing PHP with markup.

(Not a best practice)

1) if for example you have a logic on the top and you wish to generate markup, one not so good way you can do is:

<?php
$query = mysql_query("SELECT id,name FROM table");

while($row = mysql_fetch_assoc($query)){
    $id   = $row['id'];
    $name = $row['name'];
?>

<div>ID:<?php echo $id;?></div>
<div>NAME:<?php echo $name;?></div>

<?php
}
?>

In the above code you have to keep track of the ending curly brace, if your application is complex it can create a problem especially in more then one level of iteration.

2) Good way to do is to make use of PHP tags such as

<?php if(count($array)):?>

    <?php foreach($array as $result):?>

        <div><?php echo result;?></div>

    <?php endforeach;?>

<?php else:?>

    <div>NO results found</div>

<?php endif;?>

Your code has no presentation issues but if it is a complex application then you need to follow best practices.

<?php
$array = array();
$query = mysql_query("SELECT id,name FROM table");

while($row = mysql_fetch_assoc($query)):
    $array[] = $row;
endwhile;
?>

Outside of PHP tag check the count of $array , if there is count then generate markup.

<?php if(count($array)):?>

    <?php foreach($array as $result):?>

        <div>ID<?php echo result['id'];?></div>
        <div>ID<?php echo result['name'];?></div>

    <?php endforeach;?>

<?php else:?>

    <div>NO results found</div>

<?php endif;?>

Using this kind of formatting you can achieve pleasing results. Try to separate or avoid mixing too much PHP with markup. If you want your presentation logic to be separated from business logic then I recommend you to use MVC model as it increases readability and maintainability.