Using Exceptions to control application flow - php

Question

I am currently writing a web app in PHP and have decided to use exceptions (duh!).
I could not find an answer to whether putting try and catch blocks in all functions would be considered bad code.
I am currently using Exceptions to handle Database errors (Application errors are handled via a simple function which just adds them to an array and then they are displayed to the user). The try blocks are placed on all functions which require a database connection.
The code in question is:
public function db_conn_verify()
{
if(!isset($this->_mysqli)){
throw new Exception("Network Error: Database connection could not be established.");
} else {
return Null;
}
}
And an example function using this code:
public function get_users() {
try {
$this->db_conn_verify();
//Rest of function code
return True;
} Catch(Exception $e) {
Core::system_error('function get_users()', $e->getMessage());
return False;
}
}
Also would it be better to extend the Exception class and then use that new Exception class to handle application errors?
Thanks

Answer 1

I suggest to you to use something like this:
public function get_users() {
try {
if( !isset($this->_mysqli) ) {
throw new Exception("Network Error: Database connection could not be established.");
}
//Rest of function code
} Catch(Exception $e) {
Core::system_error('function get_users()', $e->getMessage());
}
}
I prefer to use my exends of Exception, but is the same. For exdending exception you can see the PHP documentation to Example #5
EDIT: For an immediate use of try-catch on database connection error you can try this:
try{
$mysqli = new mysqli("localhost", "user", "password", "database");
if ($mysqli->connect_errno) {
throw new Exception("Network Error: Database connection could not be established.");
}
} Catch(Exception $e) {
Core::system_error('function get_users()', $e->getMessage());
}