How to check whether $_GET['id'] is set and it's not empty using php

Question

Here's a php code

if(isset($_GET['id'])) {
    //do something
} else {
    redirect('index.php'); //redirect is a function
}

Now if id is set (ex: index.php?id=12) then the action is performed but if id is not set (ex: index.php?id=) this shows an error, how to overcome this...??

How to determine id is an integer and it's not empty and then perform the specific action....

Edited

Thank you all for your answers but i am still getting that error...

if(isset($_GET['id'])) { // I implemented all these codes but still....
    $user= User::find_by_id($_GET['id']);
   // Database Classes Fetches user info from database
}
else {
    redirect('index.php'); //redirect function
}

If the id is 1 or greater than 1 then the script executes perfectly. ( index.php?id=1 )

But id i set id as noting i get an error i..e index.php?id=

The code should automatically redirect user to the index.php page instead of showing an error.....

ERROR : Database query failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LIMIT 1' at line 1

Answer 1

if (!empty($_GET['id']) && filter_var($_GET['id'], FILTER_VALIDATE_INT))

or

if (!empty($_GET['id']) && ctype_digit($_GET['id']))

Answer 2

What does the error tell you?

But this would check if it's set, and if it's an integer

if(isset($_GET['id']) && ctype_digit($_GET['id']) && intval($_GET['id']) > 0)

is_numeric @ php.net

Or check out ctype_digit

Answer 3

You should check both the set-status and the content:

if ( isset( $_GET['id']] ) && !empty( $_GET['id'] ) )
    // ...

Note that you should not use the value simply as it is and work with it. You should make sure that it only contains values you expect. To check for an integer, and even better to work with an integer from that on, do something like that:

$id = ( isset( $_GET['id'] ) && is_numeric( $_GET['id'] ) ) ? intval( $_GET['id'] ) : 0;

if ( $id != 0 )
    // id is an int != 0
else
    redirect('index.php');

Answer 4

How to determine id is an integer and it's not empty and then perform the specific action....

if (!empty($_GET['id']) && (intval($_GET['id']) == $_GET['id'])) {
    //do something
} else {
    redirect('index.php'); //redirect is a function
}

The above may not be the best solution, but it should work for what you need. It will not allow the id to be 0, and will require it to be an integer.

Answer 5

Well... If you're setting it up as an integer type variable, then you could do also this:

if($_GET['id'] && gettype($_GET['id']) == 'integer'){
    #do something
}else{
    #do something else
}

Answer 6

 if(isset($_GET['id']) && ctype_digit($_GET['id']) && is_numeric($_GET['id']) && $_GET['id']>0) {
  $user= User::find_by_id($_GET['id']);
  }
else {
  redirect('index.php'); //redirect function
  }

Try this and this code full pill your requirement.

Answer 7

It seems like you're just having an issue with the ?id throwing a true when you want to check if its set. Thats because it is set, but not set to a value that you would like to use.

I'm assuming the userids have to be > 0 so just do this

if (isset($_GET['id']) && $_GET['id'] > 0) {
    $user= User::find_by_id($_GET['id']);
} else {
    redirect('index.php'); 
}

Also you're prolly best cleaning the id before processing it so

$userID = isset($_GET['id']) && $_GET['id'] > 0 ? (int) $_GET['id'] : 0;

if ($userID) {
    $user= User::find_by_id($userID);
} else {
    redirect('index.php'); 
}

Theres a lot of ways to do it, personally I prefer this. It makes your code look a bit cleaner.