Calculation in virtual field not working - cakephp

Question

I am trying to calculate distance between two geographical locations. one location is entered by user.
User entered location is calculated by model and is stored in the variable.
$ulatitude=$userLocation['Location']['latitude'];
$ulongitude=$userLocation['Location']['longitude'];
I have used below code to calculate the distance.
$this->User->virtualFields['lowestDistance'] = 'round(3959 * acos(cos(radians($ulatitude)) * cos(radians(Profile.latitude )) * cos(radians(Profile.longitude) - radians($ulongitude)) + sin(radians($ulatitude)) * sin(radians(Profile.latitude)))) ';
$order = "User.lowestDistance";
$options = array(
'fields' => '
User.*, Profile.*,
round(3959 * acos(cos(radians($ulatitude)) * cos(radians(Profile.latitude )) * cos(radians(Profile.longitude) - radians($ulongitude)) + sin(radians($ulatitude)) * sin(radians(Profile.latitude)))) AS lowestDistance,
',
'order' => array($order =>'asc'),
);
Above code throws error : unknown column $ulatitude.
Is there any other way of doing this ?

Answer 1

Single quotes are not interpreted
Consider:
<?php
$foo = "A VARIABLE";
echo 'foo is $foo' . "\n";
echo "foo is $foo" . "\n";
This would output:
-> php example.php
foo is $foo
foo is A VARIABLE
In the question everything is in single quotes, they are literal strings.
Fields should be an array
Also note that this:
'fields' => 'User.*, Profile.*, ...
Is normally an array, which makes more sense when there's multiple values:
'fields' => [
'User.*',
'Profile.*',
...
]
But since you're declaring all fields plus a virtual field, it'd be included in a find call anyway - just remove the fields from the find parameters:
$this->User->virtualFields['lowestDistance'] = "round(...";
$options = [
//'fields' => [], Not necessary
'order' => [$order =>'asc']
];
$withLowestDistance = $this->User->find('all', $options);