No user data to use - php

Question

I am completing my login function for my application and I'm receiving the trying to get property of non object on a few lines. The first one is shown below that does a function call to the is_user_locked method using the object property lock_date inside the user_data object. I understand that this means that at this point their is no user_data to work with so it can not use the properties. I'm curious to know how should I account for this so that I don't abuse using too many nested if statements.
if (count($user_data) == 0) {
$output = array('content' => 'The user was not found in the database!', 'title' =>
'User Not Found');
}
if ($this->is_user_locked($user_data->lock_date)) {
$output = array('content' => 'This user account is currently locked!', 'title' =>
'Account Locked');
}
Any ideas on why this could be? Any and all suggestions would be helpful.

Answer 1

I'm curious to know how should I account for this so that I don't
abuse using too many nested if statements.
How about something like this ?
if( $user_data ) {
// $user_data contains something so let's proceed
if ($this->is_user_locked($user_data->lock_date)) {
$output = array('content' => 'This user account is currently locked!', 'title' => 'Account Locked');
}
} else {
// Nothing in $user_data so throw Exception or display error
$output = array('content' => 'The user was not found in the database!', 'title' =>
'User Not Found');
}
See this link.
if($var): same as $var == NULL.

Answer 2

What seems to be happening is $user_data->lock_date should be $user_data['lock_date']. I'm not 100% sure by the code you posted but it seems you're just referencing an array element incorrectly.
Terinary operators can be used to avoid if statements
$user_data === null ? "it's null" : "otherwise it's not";

Answer 3

i am a huge fan of negative if checks. the idea is that if you do not get what you expect, you immediately exit. this can be getting back a result, or doing a true false check. Of course you are first going to validate the user name using CI form validation. so for example in your model, the method that checks for the user name - if the result is 0, just have it return false. Then in your controller:
// Validate the user name and other form info
// if validation passes, grab the username,
// note the TRUE, that tells CI to run it through XSS clean
$username = $this->input->post( 'username', TRUE ) ;
// if we did NOT get a user back from model, immediately go to new method
if ( ! $user = $this->users_m->_findUser($username) ) {
$this->_userNotFound(); }
// similar, if the user account is locked, go to new method
// if you return an array from model this would be $user['lock_date']
elseif ($this->isUserLocked($user->lock_date) == TRUE) {
// DO NOT try and write messages etc here. put all that in a separate method
$this->_userAccountLocked(); }
else {
// you have a $user and the user is not locked
// its tempting to write a bunch of stuff here
// do not do that. keep it clean, and go to separate method
$this->_displayAccount($user) ; }
Note that i put an underscore before all the method names - CI will automatically make those private.
Also note the Camel case for method names -- versus underscores. some people prefer it.

Answer 4

You could do this:
if (count($user_data) == 0) {
$output = array('content' => 'The user was not found in the database!', 'title' =>
'User Not Found');
} else if ($this->is_user_locked($user_data->lock_date)) {
$output = array('content' => 'This user account is currently locked!', 'title' =>
'Account Locked');
}
Which is pretty much identical to your initial code, but with an else thrown in.