Using Code Igniter Model function inside JQuery Datatables render function - php

Question

I am using JQuery Datatables to display all the users of my forum in a page from a table called 'users'. I am using Code Igniter for server-side processing. I looked up the Datatables documentation on how to render data and I got it going. However, I have some PHP variables and functions that I want to echo into a JavaScript variable so I can use them within the render function for the target column. However, I am wondering how to echo a model function from a different table with a parameter into the JavaScript variable, or whether that is even a good approach. Below is my set-up. I have only posted the lines that are relevant to this question (unless I am doing it all wrong).
Model (Dashboard_model)
public function my_followee($followee) {
$username = $this->session->username;
return $this->db->get_where('followers', array('user' => $followee, 'follower' => $username))->row_array();
}
JS:
{
"targets": [-1],
"data": null,
"orderable": false,
"render": function ( data, type, full ) {
var myself = "<?php echo $this->session->username; ?>";
var is_following = "<?php echo $this->dashboard_model->my_followee('+full[1]+');" //full[1] is username column
if(is_following == false && myself !== full[1]) {
return Follow ';
} else if(is_following == true && myself !== full[1]) {
return Unfollow ';
} else if(myself == full[1]) {
return 'This is you';
}
}
}
Basically, I want to check if the loggedin user is already following the currently selected user. If no, show follow button, otherwise, show unfollow button.
When I check the page, all the buttons have follow (except the currently logged in user), whereas some should return true and show unfollow. I suspect I'm violating syntax rules in this line:
var is_following = "<?php echo $this->dashboard_model->my_followee('+full[1]+');"
I am new to JQuery and Datatables and can't seem to figure out the right way to do this. Please can someone point me to the right direction, or suggest better ways of achieving my aim? I would really appreciate the help.
EDIT
I tried this in my controller that handles the ajax call request
public function users_ajax_list()
{
$this->load->model('user/users_model', 'users');
$this->load->model('dashboard_model');
$list = $this->users->get_users();
$data = array();
foreach ($list as $user) {
if ($this->dashboard_model->my_followee($user->username) == true) {
$is_following = true;
} else {
$is_following = false;
}
$row = array();
$row[] = $user->profile_image;
$row[] = $user->username;
$row[] = ucfirst($user->surname);
$row[] = ucfirst($user->first_name);
$row[] = ucfirst($user->state);
$row[] = ucfirst($user->lga);
$row[] = $user->followers;
$row[] = $user->following;
$row[] = $user->total_posts;
$row[] = $user->gender;
$data[] = $row;
}
$output = array(
"draw" => $_POST['draw'],
"recordsTotal" => $this->users->count_all_users(),
"recordsFiltered" => $this->users->count_filtered_users(),
"data" => $data,
);
//output to json format
echo json_encode($output);
echo json_encode($is_following);
}
It produced errors: wrong JSON response. What am I doing wrong? And how is the best way to do it? And how can I access the JSON variable within the render function for the targeted column.