{"id":1043,"date":"2021-04-11T03:44:02","date_gmt":"2021-04-11T03:44:02","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=1043"},"modified":"2021-05-21T13:08:05","modified_gmt":"2021-05-21T13:08:05","slug":"php-set-exception-handler","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-oop\/php-set-exception-handler\/","title":{"rendered":"PHP Set Exception Handler"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn how to set an exception handler using the PHP set_exception_handler()<\/code> function.<\/p>\n\n\n\n

Introduction to the PHP set_exception_handler function #<\/a><\/h2>\n\n\n\n

In practice, it’s very difficult to catch every possible exception<\/a>. If an exception is uncaught, you’ll see the exception message on the page.<\/p>\n\n\n\n

PHP allows you to catch the uncaught exceptions by registering a global exception handler. <\/p>\n\n\n\n

The global exception handler allows you to show a user-friendly message to the users while logging the important information into a log file for troubleshooting later.<\/p>\n\n\n\n

To register a global exception handler, you use the set_exception_handler()<\/code> function.<\/p>\n\n\n\n

The set_exception_handler()<\/code> function accepts a callable where you can place the code to handle the uncaught exceptions. For example:<\/p>\n\n\n

<?php<\/span>\n\nset_exception_handler(function<\/span> ($ex)<\/span> <\/span>{\n\t\/\/ handle the uncaught exception<\/span>\n});<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
To use a global function, you can pass the function name to the set_exception_handler()<\/code> function like this:<\/p>\n\n\n
<?php<\/span> \n\nset_exception_handler('handle_exceptions'<\/span>);<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
class<\/span> ExceptionHandler<\/span>\n<\/span>{\n\tpublic<\/span> function<\/span> handle<\/span>(Exception $ex)<\/span>\n\t<\/span>{\n\t\t\/\/ code to handle the exception<\/span>\n\t}\n}\n\n$handler = new<\/span> ExceptionHandler();\n\nset_exception_handler([$handler, 'handle'<\/span>]);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Note that method of the object must be public to be used an exception handler.<\/p>\n\n\n\n
<?php<\/span>\n\nclass<\/span> ExceptionHandler<\/span>\n<\/span>{\n\tpublic<\/span> static<\/span> function<\/span> handle<\/span>(Exception $ex)<\/span>\n\t<\/span>{\n\t\t\/\/ code to handle the exception<\/span>\n\t\t\/\/ ...<\/span>\n\t}\n}\n\nset_exception_handler(['ExceptionHandler'<\/span>, 'handle'<\/span>]);<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
PHP set_exception_handler example #<\/a><\/h2>\n\n\n\n
First, create the following directory structure with the corresponding files like this:<\/p>\n\n\n
.\n\u251c\u2500\u2500 bootstrap.php\n\u251c\u2500\u2500 index.php\n\u2514\u2500\u2500 logs\n    \u2514\u2500\u2500 errors.log<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
Filename<\/th>Directory<\/th>Description<\/th><\/tr><\/thead>
bootstrap.php<\/td>.<\/td>contains the code for bootstrapping the application<\/td><\/tr>
index.php<\/td>.<\/td>is the entry page of the application<\/td><\/tr>
errors.log<\/td>logs<\/td>contains the logging information<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Second, add the following code to the bootstrap.php<\/code> file:<\/p>\n\n\n
<?php<\/span>\n\nset_exception_handler(function<\/span> (Exception $ex)<\/span> <\/span>{\n\t\/\/ set default timezone<\/span>\n\tdate_default_timezone_set('America\/Los_Angeles'<\/span>);\n\n\t\/\/ get the current date & time<\/span>\n\t$time = date('F j, Y, g:i a e O'<\/span>);\n\n\t\/\/ format the exception message<\/span>\n\t$message = \"[{$time}] {$ex->getMessage()}\\n\"<\/span>;\n\n\t\/\/ append to the error log<\/span>\n\terror_log($message, 3<\/span>, 'logs\/errors.log'<\/span>);\n\n\t\/\/ show a user-friendly message<\/span>\n\techo<\/span> 'Whoops, looks like something went wrong!'<\/span>;\n});\n\n<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
In the bootstrap.php<\/code> file, we set the default time zone to 'America\/Los_Angeles'<\/code>, get the current date and time, format the exception message, and log it into the errors.log<\/code> file located in the logs<\/code> directory.<\/p>\n\n\n\n
The second argument (3<\/code>) of the error_log()<\/code> function indicates that it will append the log entry in the errors.log<\/code> file.<\/p>\n\n\n\n
Third, place the following code in the index.php<\/code> file:<\/p>\n\n\n
<?php<\/span>\n\nrequire<\/span> 'bootstrap.php'<\/span>;\n\nfunction<\/span> add<\/span>($a, $b)<\/span>\n<\/span>{\n\tif<\/span> (!is_numeric($a) || !is_numeric($a)) {\n\t\tthrow<\/span> new<\/span> InvalidArgumentException('Both arguments must be numeric or numeric strings'<\/span>);\n\t}\n\n\treturn<\/span> $a + $b;\n}\n\necho<\/span> add('Hi'<\/span>, 'there'<\/span>);\n<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
The index.php<\/code> includes<\/a> the bootstrap.php<\/code> file. And it defines a function called add()<\/code> that returns the sum of two numbers. <\/p>\n\n\n\n
However, the function call add('Hi', 'there')<\/code> uses string arguments instead of numbers. Therefore, it’ll throw an exception<\/a> InvalidArgumentException<\/code>.<\/p>\n\n\n\n
Since this exception is not caught in the index.php<\/code>, the global exception handler will catch it. The index.php<\/code> will show the following message:<\/p>\n\n\n
Whoops, looks like something went wrong!<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
If you look at the errors.log<\/code> file, you’ll find something like:<\/p>\n\n\n
[April 10, 2021, 8:35 pm America\/Los_Angeles -0700] File: ...\\index.php, Line: 8, Message: Both arguments must be numeric or numeric strings<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
  • Use the set_exception_handler()<\/code> function to register a global exception handler that handles uncaught exceptions.<\/li><\/ul>\n
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    Did you find this tutorial useful?<\/div>\n\t\t
    \n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t Yes <\/span>\n\t\t\t<\/button>\n\n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t No <\/span>\n\t\t\t<\/button>\n\t\t<\/div>\n\t<\/header>\n\n\t
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    <\/div>\n\t\t\t\n\t\t\t
Similary, you can use a public static method<\/a> of a class as the exception handler:<\/p>\n\n\n
In case you want to use a method of an object<\/a>, you need to pass an array<\/a> with the first element is the object and the second element is the method name. For example:<\/p>\n\n\n