You should not use in_array('user_id', $id) on that function because it returns boolean.
On the active record page: https://ellislab.com/codeigniter/user-guide/database/active_record.html you can take a look at parameter it takes for get_where() function
$query = $this->db->get_where('mytable', array('id' => $id), $limit, $offset);
Notice how the third parameter takes $limit which talks about the number of data you'll receive. (Leaving this blank will return you all data).
Some code examples:
If you just want to get the data with status = 1, use the following:
$query = $this->db->get_where('post_meta',array('status'=>1));
If you want to get the data with status = 1 and user_id = $id, use the following:
$this->db->like('value', '"user_id":"'.$id.'"');
$query = $this->db->get_where('post_meta',array('status'=>1));
The solution above is not the best, but it should work.
The $this->db->like() function will create rules to get data in value row which has "user_id":"$id" where $id is the value that you define.
What if I want to get all notifications and group them based on their ID?
I usually get all the data and then use PHP to group them into its own array. I think it's cheaper than relying on database to do that (Correct me if i'm wrong).
So use the first code:
$query = $this->db->get_where('post_meta',array('status'=>1));
Then iterate them using foreach() or whatever you find convenient.
$data = array();
foreach($query as $k=>$v) {
// Run a function to get User ID
$user_id = your_function_here($v->value);
if(!isset($data[$user_id]))
$data[$user_id] = array();
// This is just some example to group them together, you can optimize it to your own liking
array_push($data[$user_id],$v);
}
your_function_here() is your function to get the user_id from value row on your database.