Learn PHP JSON File Handling with Practical Examples

Introduction to JSON in PHP

JSON (JavaScript Object Notation) is a lightweight data interchange format that’s easy for humans to read and write and easy for machines to parse and generate. PHP provides a built-in function to handle JSON, making it simple to read from and write to JSON files. Here, we’ll explore three practical examples of using PHP to read and write JSON files.

Example 1: Writing Data to a JSON File

Context

In this example, we’ll create a simple PHP script to store user information in a JSON file. This can be useful for saving settings or user profiles.

<?php
// Sample user data to be written to JSON file
$userData = [
    'name' => 'John Doe',
    'email' => 'john.doe@example.com',
    'age' => 30
];

// Convert the array to JSON format
\(jsonData = json_encode(\)userData, JSON_PRETTY_PRINT);

// Specify the file name
$file = 'user_data.json';

// Write JSON data to the file
if (file_put_contents(\(file, \)jsonData)) {
    echo "Data successfully written to $file";
} else {
    echo "Error writing data to $file";
}
?>

Notes

• The JSON_PRETTY_PRINT option makes the JSON output more readable.
• Always ensure that your file path is writable and check for errors when writing to files.

Example 2: Reading Data from a JSON File

Context

Now, let’s create a script to read the user data we just saved in the JSON file. This is often necessary when you want to retrieve stored information.

<?php
// Specify the file name
$file = 'user_data.json';

// Check if the file exists
if (file_exists($file)) {
    // Get the contents of the file
    \(jsonData = file_get_contents(\)file);

    // Decode the JSON data into a PHP array
    \(userData = json_decode(\)jsonData, true);

    // Display the user data
    echo "Name: " . $userData['name'] . "\n";
    echo "Email: " . $userData['email'] . "\n";
    echo "Age: " . $userData['age'] . "\n";
} else {
    echo "File not found: $file";
}
?>

Notes

• The json_decode function converts JSON data back into a PHP array. Setting the second parameter to true returns an associative array.
• Always check if the file exists before attempting to read it.

Example 3: Updating Data in a JSON File

Context

In this example, we will update the user data stored in the JSON file. This is useful when user information changes and needs to be refreshed.

<?php
// Specify the file name
$file = 'user_data.json';

// Check if the file exists
if (file_exists($file)) {
    // Read the current data from the file
    \(jsonData = file_get_contents(\)file);
    \(userData = json_decode(\)jsonData, true);

    // Update user information
    $userData['age'] = 31; // Updating age

    // Convert the updated array to JSON format
    \(jsonData = json_encode(\)userData, JSON_PRETTY_PRINT);

    // Write the updated data back to the file
    if (file_put_contents(\(file, \)jsonData)) {
        echo "Data successfully updated in $file";
    } else {
        echo "Error updating data in $file";
    }
} else {
    echo "File not found: $file";
}
?>

Notes

• This example demonstrates how to maintain user data by updating specific fields.
• Always ensure that the data you’re updating conforms to the expected structure to avoid errors.