php-the-right-way/_posts/07-04-01-Interacting-via-Code.md

isChild, title, anchor

isChild	title	anchor
true	Interacting with Databases	databases_interacting

Interacting with Databases

When developers first start to learn PHP, they often end up mixing their database interaction up with their presentation logic, using code that might look like this:

{% highlight php %}

<?php foreach ($db->query('SELECT * FROM table') as $row) { echo "
• ".$row['field1']." - ".$row['field1']."
"; } ?>

{% endhighlight %}

This is bad practice for all sorts of reasons, mainly that it's hard to debug, hard to test, hard to read and it is going to output a lot of fields if you don't put a limit on there.

While there are many other solutions to doing this - depending on if you prefer OOP or functional programming - there must be some element of separation.

Consider the most basic step:

{% highlight php %}

<?php function getAllFoos($db) { return $db->query('SELECT * FROM table'); } $results = getAllFoos($db); foreach ($results as $row) { echo "

".$row['field1']." - ".$row['field1']."

"; // BAD!! } {% endhighlight %} That is a good start. Put those two items in two different files and you've got some clean separation. Create a class to place that method in and you have a "Model". Create a simple `.php` file to put the presentation logic in and you have a "View", which is very nearly [MVC] - a common OOP architecture for most [frameworks](/#frameworks). **foo.php** {% highlight php %} <?php $db = new PDO('mysql:host=localhost;dbname=testdb;charset=utf8mb4', 'username', 'password'); // Make your model available include 'models/FooModel.php'; // Create an instance $fooModel = new FooModel($db); // Get the list of Foos $fooList = $fooModel->getAllFoos(); // Show the view include 'views/foo-list.php'; {% endhighlight %} **models/FooModel.php** {% highlight php %} <?php class FooModel { public function __construct(protected PDO $db) { } public function getAllFoos() { return $this->db->query('SELECT * FROM table'); } } {% endhighlight %} **views/foo-list.php** {% highlight php %} <?php foreach ($fooList as $row): ?>

<li><?= $row['field1'] ?> - <?= $row['field1'] ?></li>

<?php endforeach ?>

{% endhighlight %}

This is essentially the same as what most modern frameworks are doing, albeit a little more manual. You might not need to do all of that every time, but mixing together too much presentation logic and database interaction can be a real problem if you ever want to unit-test your application.