More on Update Records

The controller

We’ll use the same file that we used for the “Add a project” feature to implement our controller code: /controllers/project.php.

First, we’ll initialize variables to an empty string:

$project_title = $category = '';

This line of code is added just after the require statements.

We know that when the user clicks a list item from the project list, the item id is passed on to the URL. Therefore, we can capture this id with the $_GET variable in order to select the given project from the database.

if (isset($_GET['id'])) {
    list($id, $project_title, $category) = get_project($_GET['id']);
}

The get_project($id) function does not exist yet. We’ll create it in the model.

Note: list() is a built-in PHP function, which helps us assign a list of variables in one operation.

<?php
$projectInfo = array(1, 'Learn PHP', 'Personal');
// We can pick only some variables
list(, $title, $category) = $projectInfo;
?>

The last thing to do is to pass the $id as the third parameter to the add_project() function when the user submits the form.

$id = null;

if (isset($_POST['id'])) {
        $id = $_POST['id'];
    }

Now we can call the function like this:

if (add_project($title, $category, $id)) {
                header('Refresh:4; url=project_list.php');
                if (!empty($id)) {
                    $confirm_message = escape($title) . ' updated successfully';
                } else {
                    $confirm_message = escape($title) . ' added successfully';
                }
            }

The model

Now, in model.php, let’s create the function to select one project:

function get_project($id)
{
    try {
        global $connection;

        $sql =  'SELECT * FROM projects WHERE id = ?';
        $project = $connection->prepare($sql);
        $project->bindValue(1, $id, PDO::PARAM_INT);
        $project->execute();

        return $project->fetch();
    } catch (PDOException $exception) {
        echo $sql . "<br>" . $exception->getMessage();
        exit;
    }
}

We can now add $id as the last parameter of the add_project() function. Inside the function, we can add the $sql function to update data:

if ($id) {
            $sql = 'UPDATE projects SET title = ?, category = ? WHERE id = ?';
        } else {
            $sql =  'INSERT INTO projects(title, category) VALUES(?, ?)';
        }

      // code here does not change
        if ($id) {
            $new_project = array($title, $category, $id);
        }
// code here does not change

That’s all. Let’s see it live and confirm whether it works.

Our accomplishment

So far, we’ve learned step by step how to update the project records. We can find the source code here.