How to Add a Prefix to Generated License Keys with SunLicense

Pass a string to the SunLicense constructor to automatically prepend a custom prefix followed by a hyphen to every generated license key.

The SunLicense class in the msbatal/php-license-key-generator repository provides a straightforward mechanism to add a prefix to generated license keys with SunLicense through its constructor-based configuration. By initializing the class with a specific prefix string, developers can brand their license keys while maintaining the library's template-driven generation logic.

Understanding the SunLicense Prefix Architecture

The $prefix Property

The prefix functionality centers on a private $prefix property defined in SunLicense.php. This property stores the optional string that appears before the generated key segments. When populated, it serves as the root identifier for your application or product line.

Constructor Initialization

Prefix assignment occurs during object instantiation. In SunLicense::__construct() (lines 56–62), the constructor receives the $prefix parameter and assigns it to $this->prefix if the value is not empty. This design ensures that the prefix is immutable for the lifetime of the generator instance, providing consistent key formatting across multiple generation calls.

How the Prefix is Applied During Key Generation

The license() Method Logic

The actual prefix injection happens inside SunLicense::license() (lines 79–84). When $this->prefix is set, the method concatenates the prefix followed by a hyphen character ('-') to the $key variable before processing the template. This hardcoded separator ensures visual distinction between the product identifier and the random key segments.

Template Processing After Prefix

Following the prefix attachment (lines 84–95), the method iterates through the $template string. It substitutes X characters with random letters and 9 characters with random digits, appending these to the prefixed string. Because the prefix is prepended as a discrete block, the template defines only the variable portion of the key, keeping the branding element separate from the entropy source.

Practical Code Examples

Generate a Single Key with a Custom Prefix

To create a branded license key, instantiate SunLicense with your product identifier as the first argument:

require_once 'SunLicense.php';

// Initialize with "MYAPP" prefix, default template, uppercase letters
$lic = new SunLicense('MYAPP');
echo $lic->generate();   // Output: MYAPP-K7FQ84-AB12-7K9Q-48LM7P

Generate Multiple Keys with Prefix and Custom Template

Combine prefix branding with custom templates and batch generation:

require_once 'SunLicense.php';

$prefix   = 'PROD';
$template = 'XX99-9X9X';
$count    = 5;

$lic = new SunLicense($prefix, $template, 'upper', $count);
$keys = $lic->generate();   // Returns array of 5 keys
print_r($keys);
// Output: [PROD-AB12-3C4D, PROD-EF56-7G8H, ...]

Omitting the Prefix for Default Behavior

If you do not require branding, omit the prefix argument to generate keys matching the template exactly:

$lic = new SunLicense();   // No prefix argument
echo $lic->generate();     // Output: X7QG84-AB12-7K9Q-48LM7P

Key Implementation Files

The prefix functionality is implemented across the following files in the msbatal/php-license-key-generator repository:

• SunLicense.php – Defines the SunLicense class, including the $prefix property, constructor logic (lines 56–62), and the license() method (lines 79–95) that handles prefix concatenation.
• test/SunLicense.php – Contains example usage patterns and a simple test harness demonstrating various prefix configurations.
• test/index.php – Entry point for manual testing, showing instantiation examples with and without prefixes.

Summary

• Prefix configuration occurs via the SunLicense constructor, which stores the value in a private $prefix property.
• Automatic formatting prepends the prefix followed by a hyphen during the license() method execution, separating the brand identifier from the random key segments.
• Template independence ensures that the prefix does not interfere with the X and 9 substitution logic, maintaining consistent key entropy regardless of branding.
• Optional implementation allows developers to omit the prefix entirely, generating keys that match the template pattern without additional identifiers.

Frequently Asked Questions

Can I add a prefix to existing keys without regenerating them?

No, the SunLicense class applies prefixes during the generation phase within the license() method. To add prefixes to existing keys, you would need to manually concatenate the prefix and hyphen to your stored keys or regenerate them using the constructor-based prefix configuration.

What happens if I pass an empty string as the prefix?

The constructor checks if the prefix parameter is not empty before assigning it to $this->prefix (lines 60–62 in SunLicense.php). Passing an empty string results in the prefix remaining unset, causing the license() method to skip the prefix concatenation step and generate keys matching the template exactly.

Is there a maximum length limit for the prefix?

The source code does not enforce a maximum length limit on the $prefix property. However, practical considerations for database storage and key readability suggest keeping prefixes under 10–15 characters. The hyphen separator is hardcoded, so extremely long prefixes will increase total key length linearly.

Can I change the separator between prefix and key?

The hyphen separator is hardcoded in the license() method at line 81: $key = $this->prefix . '-';. To use a different separator, you would need to modify the source code in SunLicense.php or extend the class to override the license() method with your preferred delimiter logic.

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