PHP MongoDB Driver Query Only Specific Field From All Documents In Collection

Question

Ok, guys. As most of you might know, there is this new MongoDB Driver for PHP 7 out there. I was trying it out. I got stuck at this query here :

There is a collection like this:

{ 
"_id" : ObjectId("592d026e2a5e742704e60055"), 
"name" : "One", 
"conn" : [
    {
        "_id" : ObjectId("592d03cd3c83d5265c004d0b"), 
        "name" : "MongoDB Fans", 
        "comments" : "nice!"
    }, 
    {
        "_id" : ObjectId("592d06513c83d5265c004d17"), 
        "name" : "SQL Fans", 
        "comments" : "not so nice!"
    }
   ]
},
{ 
"_id" : ObjectId("592d0eec2a5e742704e60056"), 
"name" : "Two", 
"conn" : [
    {
        "_id" : ObjectId("592d0ef13c83d5265c004d37"), 
        "name" : "Cassandra Fans", 
        "comments" : "spooky!"
    }
   ]
  }

Now, what I want to achieve is this: 1. Find all "conn" fields (irrespective of which document they belong to) that contain a user input (say "xyz") in "name" as a sub-string. 2. Project the selected "conn" fields out.

I have tried using the following filters and options without success (Almost all of these return all the "conn" subsets instead of only the filtered subsets):

1. $filters = ["conn.name" => new MongoDB\BSON\Regex($name,'i')]; $options = ["projection" => ["_id" => 0,"conn" =>1];
2. $filters = ["conn" => ["\$all" =>["name" => new MongoDB\BSON\Regex($name,'i')]]]; $options = ["projection" => ["_id" => 0,"conn" =>1];
3. $filters = ["conn.name" => '/'.$name.'/i']; $options = ["projection" => ["_id" => 0,"conn" =>1];

NOTE: I am using PHP 7 and the latest mongod PECL extension