How to catch warnings for mysqli_connect()

Question

How do I catch warnings for mysqli_connect()

Example

if (!$connection2 = mysqli_connect($host, $username, $password, $name)){
    die('MySQL ERROR: ' . mysql_error()); 
}

OR

$connection2 = mysqli_connect($host, $username, $password, $name);
if (!$connection2){
    die('MySQL ERROR: ' . mysql_error()); 
}

So, I am trying to test mysqli_connect() method by putting wrong host, username etc. in it. But when I put the wrong variables in it such as I put hostlocal instead of localhost. It gives me this error

Warning: mysqli_connect(): php_network_getaddresses: getaddrinfo failed:
No such host is known.

I know I am putting the wrong host in it but I want to catch the errors in an appropriate way. A decent message would be perfect just like:

Unfortunately, the details you entered for connection are incorrect!

How do I get this message instead of the warning?

Answer 1

For one, mysql_error() won't give you anything. It's a part of another library, mysql_, which doesn't interchange with the new and improved mysqli_. That being said, you can set MySQLi to throw exceptions, which you then can catch.

The warnings would still be logged, if error-logging is enabled (as it should!). But you can catch the error and display something more user-friendly to the page if the connection fails. You should never display actual error messages to a live project - in development its fine, but never on any live environment.

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); // Set MySQLi to throw exceptions 

try {
    $connection2 = mysqli_connect($host, $username, $password, $name);
} catch (mysqli_sql_exception $e) {
    // $e is the exception, you can use it as you wish 
    die("Unfortunately, the details you entered for connection are incorrect!");
}

This would however log the same warning as what you're getting to the log,

php_network_getaddresses: getaddrinfo failed: Name or service not known

although it won't be displayed to the page.

You can suppress the warning (so it won't be logged) by adding @, but I don't recommend it unless you explicitly implement your own error-handling/reporting. Errors should be logged.

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); // Set MySQLi to throw exceptions 

try {
    $connection2 = @mysqli_connect($host, $username, $password, $name);
} catch (mysqli_sql_exception $e) {
    error_log($e->getMessage()); // Log the error manually
    die("Unfortunately, the details you entered for connection are incorrect!");
}

• http://php.net/manual/en/class.mysqli-sql-exception.php