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# zend-psr-log
## Overview
A number of PHP libraries accept a `Psr\Log\LoggerInterface` for logging messages. Unfortunately, applications using
[Zend Framework 2](https://github.com/zendframework/zf2) cannot provide their existing `Zend\Log\Logger` loggers, as
they don't comply with [PSR-3](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-3-logger-interface.md).
In fact, the two interfaces are not compatible, as they declare some common methods with different
signatures. For example:
[Zend alert](https://github.com/zendframework/zendframework/blob/release-2.1.0/library/Zend/Log/LoggerInterface.php#L28) vs.
[Psr alert](https://github.com/php-fig/log/blob/504b915845b0fe47819fcbabbfbea18e95f5cf5c/Psr/Log/LoggerInterface.php#L41).
This library serves as a backwards-compatible replacement for `Zend\Log\Logger` instances that provides a
[Psr\Log](https://github.com/php-fig/log)-compliant interface to the underlying `Zend\Log\Logger` instance. The
result is that you can provide either logger depending on the interface required by a given context, while still
having all messages go through `Zend\Log\Logger` and benefiting from its robustness.
## Installation
The only supported method of installation is [Composer](https://getcomposer.org/).
`composer require "michaelmoussa/zend-psr-log"`
## Configuration
To begin, you must add the `ZendPsrLog` module to your `application.config.php` module list as with any ZF2 application.
```php
return [
'modules' => [
...,
'ZendPsrLog',
...
],
...
];
```
Further configuration depends on how you are presently getting your instances of a `Zend\Log\Logger`.
### "I define a `log` entry in my configuration with `Zend\Log\Logger` as the key, and then let `Zend\Log\LoggerAbstractServiceFactory` do the work."
Then you're done! `ZendPsrLog` adds its own factory for creating `Zend\Log\Logger` instances, which will be invoked
before the Abstract Factory.
### "I define a `log` entry in my configuration with a different key, then let `Zend\Log\LoggerAbstractServiceFactory` do the work."
For each key you use, you'll need to add a `'My\Key\Here' => new \ZendPsrLog\LoggerFactory('My\Key\Here')` entry to
your service manager config.
### "I define a log key in my configuration with no key, and then have my own `'Zend\Log\Logger' => '...'` factory definition in the service manager config"
You need to replace your `'Zend\Log\Logger' => '...'` entry with
`'Zend\Log\Logger' => new \ZendPsrLog\LoggerFactory(null)`, as your definition will override the one done by the
`ZendPsrLog\LoggerFactory`.
If your custom factory is doing some special logic, you will have to extend `ZendPsrLog\LoggerFactory` on your own to
ensure it persists.
### "I use `new \Zend\Log\Logger(...)`."
1. Please don't. :) You should be using the `ServiceManager`.
2. Replace `new \Zend\Log\Logger` with `new \ZendPsrLog\Logger`.
## Usage
### As a `Zend\Log\LoggerInterface`
The `ZendPsrLog\Logger` is an extension of `Zend\Log\Logger`, so any class you have in your application that is
presently using a `Zend\Log\Logger` can use the `ZendPsrLog\Logger` without any additional configuration.
### As a `Psr\Log\LoggerInterface`
Suppose you have a class that requires a `Psr\Log\LoggerInterface` instance:
```php
use Psr\Log\LoggerInterface;
class Foo
{
public function __construct(LoggerInterface $logger) { ... }
}
```
And you obtain an instance of the `ZendPsrLog\Logger`:
```php
/** @var \ZendPsrLog\Logger $logger */
$logger = $serviceManager->get('Zend\Log\Logger');
```
Just use the `->getPsrLogger()` method to obtain a `Psr\Log\LoggerInterface` to your existing `Zend\Log\Logger`:
```php
$foo = new Foo($logger->getPsrLogger());
```