PHP: Avoid undefined index?

Question

Every time a POST value is not equal to the list of values set in an array will return: Undefined Index error, I made an if statement but is not working.

Here\'s the

Answer 1

I'm a bit confused by your code. It looks like your array has the same key and value, so:

$products['saucepan'] = 'saucepan'

Perhaps you are trying to do this, which will check whether the product exists in the products array:

if(isset($_POST['product']) && array_key_exists($_POST['product'], $products))
{
  // do stuff
}
else
{
  echo "This item is not available";
}

Answer 2

You can just use a ?? to set set a default value if your value is not set.

$_POST['product'] ?? "No product";

Answer 3

With PHP 7, the null coalescing operator can be used to deal with optional request variables. You can change your $_POST['product'] reference to $_POST['product'] ?? null which will resolve to null (rather than throwing the warning) if 'product' is not a valid key in the post array. If you wanted to check both the $_POST and $_GET arrays for a value, you would use $_POST['product'] ?? $_GET['product'] ?? null.