A Writer is an object that inherits from Zend_Log_Writer_Abstract
. A Writer's
responsibility is to record log data to a storage backend.
Zend_Log_Writer_Stream
sends log
data to a PHP stream.
To write log data to the PHP output buffer, use the URL php://output
. Alternatively,
you can send log data directly to a stream like STDERR
(php://stderr
).
$writer = new Zend_Log_Writer_Stream('php://output'); $logger = new Zend_Log($writer); $logger->info('Informational message');
To write data to a file, use one of the Filesystem URLs:
$writer = new Zend_Log_Writer_Stream('/path/to/logfile'); $logger = new Zend_Log($writer); $logger->info('Informational message');
By default, the stream opens in the append mode ("a"
).
To open it with a different mode, the Zend_Log_Writer_Stream constructor
accepts an optional second parameter for the mode.
The constructor of Zend_Log_Writer_Stream
also accepts an existing stream resource:
$stream = @fopen('/path/to/logfile', 'a', false); if (! $stream) { throw new Exception('Failed to open stream'); } $writer = new Zend_Log_Writer_Stream($stream); $logger = new Zend_Log($writer); $logger->info('Informational message');
You cannot specify the mode for existing stream resources. Doing so
causes a Zend_Log_Exception
to be thrown.
Zend_Log_Writer_Db
writes log information to a database table using
Zend_Db
. The constructor of Zend_Log_Writer_Db
receives
a Zend_Db_Adapter
instance, a table name, and a mapping of database
columns to event data items:
$params = array ('host' => '127.0.0.1', 'username' => 'malory', 'password' => '******', 'dbname' => 'camelot'); $db = Zend_Db::factory('PDO_MYSQL', $params); $columnMapping = array('lvl' => 'priority', 'msg' => 'message'); $writer = new Zend_Log_Writer_Db($db, 'log_table_name', $columnMapping); $logger = new Zend_Log($writer); $logger->info('Informational message');
The example above writes a single row of log data to the database table named
log_table_name
table. The database column named lvl
receives the priority number and the column named msg
receives the
log message.
Zend_Log_Writer_Firebug
sends log
data to the Firebug
Console.
All data is sent via the Zend_Wildfire_Channel_HttpHeaders
component
which uses HTTP headers to ensure the page content is not disturbed.
Debugging AJAX requests that require clean JSON and XML responses is possible with this approach.
Requirements:
Firefox Browser ideally version 3 but version 2 is also supported.
Firebug Firefox Extension which you can download from https://addons.mozilla.org/en-US/firefox/addon/1843.
FirePHP Firefox Extension which you can download from https://addons.mozilla.org/en-US/firefox/addon/6149.
Example 30.1. Logging with Zend_Controller_Front
// Place this in your bootstrap file before dispatching your front controller $writer = new Zend_Log_Writer_Firebug(); $logger = new Zend_Log($writer); // Use this in your model, view and controller files $logger->log('This is a log message!', Zend_Log::INFO);
Example 30.2. Logging without Zend_Controller_Front
$writer = new Zend_Log_Writer_Firebug(); $logger = new Zend_Log($writer); $request = new Zend_Controller_Request_Http(); $response = new Zend_Controller_Response_Http(); $channel = Zend_Wildfire_Channel_HttpHeaders::getInstance(); $channel->setRequest($request); $channel->setResponse($response); // Start output buffering ob_start(); // Now you can make calls to the logger $logger->log('This is a log message!', Zend_Log::INFO); // Flush log data to browser $channel->flush(); $response->sendHeaders();
Built-in and user-defined priorities can be styled with the setPriorityStyle()
method.
$logger->addPriority('FOO', 8); $writer->setPriorityStyle(8, 'TRACE'); $logger->foo('Foo Message');
The default style for user-defined priorities can be set with the setDefaultPriorityStyle()
method.
$writer->setDefaultPriorityStyle('TRACE');
The supported styles are as follows:
Table 30.1. Firebug Logging Styles
Style | Description |
---|---|
LOG |
Displays a plain log message |
INFO |
Displays an info log message |
WARN |
Displays a warning log message |
ERROR |
Displays an error log message that increments Firebug's error count |
TRACE |
Displays a log message with an expandable stack trace |
EXCEPTION |
Displays an error long message with an expandable stack trace |
TABLE |
Displays a log message with an expandable table |
While any PHP variable can be logged with the built-in priorities, some special formatting is required if using some of the more specialized log styles.
The LOG
, INFO
, WARN
, ERROR
and TRACE
styles require no special formatting.
To log a Zend_Exception
simply pass the exception object to the logger.
It does not matter which priority or style you have set as the exception is automatically
recognized.
$exception = new Zend_Exception('Test exception'); $logger->err($exception);
You can also log data and format it in a table style. Columns are automatically recognized and the first row of data automatically becomes the header.
$writer->setPriorityStyle(8, 'TABLE'); $logger->addPriority('TABLE', 8); $table = array('Summary line for the table', array( array('Column 1', 'Column 2'), array('Row 1 c 1',' Row 1 c 2'), array('Row 2 c 1',' Row 2 c 2') ) ); $logger->table($table);
The Zend_Log_Writer_Null
is a stub that does not write log data to anything.
It is useful for disabling logging or stubbing out logging during tests:
$writer = new Zend_Log_Writer_Null; $logger = new Zend_Log($writer); // goes nowhere $logger->info('Informational message');
The Zend_Log_Writer_Mock
is a very simple writer that records
the raw data it receives in an array exposed as a public property.
$mock = new Zend_Log_Writer_Mock; $logger = new Zend_Log($mock); $logger->info('Informational message'); var_dump($mock->events[0]); // Array // ( // [timestamp] => 2007-04-06T07:16:37-07:00 // [message] => Informational message // [priority] => 6 // [priorityName] => INFO // )
To clear the events logged by the mock, simply set $mock->events = array()
.
There is no composite Writer object. However, a Log instance can write
to any number of Writers. To do this, use the addWriter()
method:
$writer1 = new Zend_Log_Writer_Stream('/path/to/first/logfile'); $writer2 = new Zend_Log_Writer_Stream('/path/to/second/logfile'); $logger = new Zend_Log(); $logger->addWriter($writer1); $logger->addWriter($writer2); // goes to both writers $logger->info('Informational message');