Throw exception ends execution - how can I display rest of page

conjurer

I am modifying some code and I have an error handler set up as follows:

function handle_exception($exception) 
{
    echo "<p><strong>Problem:  </strong>{$exception->getMessage()}\n</p>";

}

My login form takes a potential user to my welcome page where the login functions are processed. I am trying to test the portion where the login fails because the username and password did not match a combination in my database. The message is set and triggered as follows:

 else 
    {$errmsg = "Login Failed: the username/password combination failed!";

 throw new Exception($errmsg);  

 }

This is in the middle of my page so when it triggers the rest of my page never gets generated so text is lost and never displays and tags are left open for some divs, body, etc. :eek:

Is there a way to have it return to a place in the document and process from there down so that the document renders fully with the error message in the middle of the page?

bradgrafelman

How are you handling the exception? The whole point of using exceptions is that you can then surround the appropriate code in try/catch blocks to trap the exceptions and then continue executing the rest of the code.

conjurer

bradgrafelman;10966219 wrote:
How are you handling the exception? The whole point of using exceptions is that you can then surround the appropriate code in try/catch blocks to trap the exceptions and then continue executing the rest of the code.

I seem to be missing that try catch stuff.

:-)

So I have the handler setup and a login script that dumps to it. How would I use the try/catch in the following login script around that error? The error happens in that last else clause. How would I use try/catch in this, cause that sounds like xactly what I need! Thanks!!!

function login($username, $passwd, $conn) //added $conn
// check username and password with db
// if yes, return true
// else throw exception
{
  // connected to db
  if (!$conn) echo "<h2 .msg>Connection Error for user $username using $passwd at line: ".__LINE__ ."</h2>";

  // encode password, create query, and check if username/password is valid
  $enc_passwd= sha1($passwd);
  $userquery ="select * from users where username='".$username ."'
                         and password ='".$enc_passwd ."'";
  // 
  echo "<p .msg>Executing query: ".$userquery ."</p>";
  $result = mysqli_query($conn,$userquery);  

  if (!$result){    

    $errmsg = "<h2.msg>Login query failed at line: " .__Line__."</h2>
            mysqli_connect_error: ".mysqli_connect_error()."<br />";                             

     throw new Exception($errmsg);
  }

  //
  echo "<p>login() function - query was valid, checking to see if user and password returned a row ...</p>";
  if (mysqli_num_rows($result)>0)
      {
        return true;
      }
  else 
    {$errmsg = "Login Failed: the username/password combination failed!";

 throw new Exception($errmsg);  

 }
}

bradgrafelman

Er... you're using exceptions but you don't have any try/catch blocks? Why in the world are you using exceptions in the first place??

Take a look at the PHP manual page on [man]exceptions[/man] (or just Google any exception handling tutorial - even if they refer to a language like C++, the logic (and even most of the syntax) is going to be the same).

conjurer

bradgrafelman;10966228 wrote:
Er... you're using exceptions but you don't have any try/catch blocks? Why in the world are you using exceptions in the first place??

😃 because I don't know what I am doing?

Thanks for pointing me in the right direction.

NogDog

Generally speaking (and others may argue otherwise) I save exceptions for things that are most likely a programmer or system error, and therefore are "exceptional". User errors that are expected, such as an invalid login, are probably better handled by if/else types of validations. So it might make sense to throw an exception for a failed database connection, whereas the invalid login would probably better be dealt with by, perhaps, returning false and possibly setting an error message in a passed-by-reference variable.

function login($username, $passwd, $conn, &$errmsg) // note "&" for last variable
{
   // . . .
   else {
      $errmsg = "Invalid login name and/or password";
      $return false;
   }
}

// USAGE:
try {
   $result = login($foo, $bar, $fubar, $error);
   if($result == false) {
      // output error page, using $error
      exit;
   }
}
catch(Exception $e) {
   // do whatever you want to do in case of an exception
   error_log((string) $e);
   echo "unexpected error!";
   exit;
}
// rest of page....

conjurer

Thanks for the clarification. Trying it out. 🙂

conjurer

function login($username, $passwd, $conn, &$errmsg) // note "&" for last variable
{
   // . . .
   else {
      $errmsg = "Invalid login name and/or password";
      $return false;
   }
}

Is there supposed to be a dollar sign on the return? If so why use a dollar sign here and other places not?😕

NogDog

Nah, just a typo. "return" is a PHP command, not a variable. 🙂