使用Spark在Codeigniter中获取api where子句

I'm using spark in codeigniter as a rest client to talk to the service. The apis are already built separately in swagger.

I'm trying to do an user login functionality. This is my api model schema:

{
  "name": "string",
  "email": "string",
  "password": "string",
  "mobile": "string",
  "accType": "string",
  "meta": "string",
  "createdAt": 0
}

For testing user existence, this is my code :

   function __construct(){

     parent::__construct();

     $this->load->library('rest', array(
      'server' => 'http://stage.cogxio.co:7070/',
      'api_key'  => 'local',
      'api_name' => 'X-API-KEY',
    ));
  }

  function user_exist($data){

    $response = $this->rest->get('user/email/'.$data, 'json');

    if(property_exists($response, "STATUS")){
      $result_code = $response->STATUS;
      if($result_code == 200){
       return true;
      }else{
        return false;
      }

    } else {
      return "server error";
    }

  }

The return of 1 will tell that the email exists otherwise does not exist.

When that checking is over, then I need to check whether the email and password are matching, that is "WHERE email=$email && password=$password"

Since, I'm new to api, I don't know how to do that.

I know, I need to pass two variables.

function login_match($email, $password){
 $response = $this->rest->get('user/email/??, 'json'); // what to do with this field?
}

I don't know how to use the where clause here.