public function equalTo($key, $value)
    {
        if ($value === null)
        {
            $this->doesNotExist($key);
        } else
        {
            $this->where[$key] = $value;
        }

        return $this;
    }
public function equalTo($key, $value)
    {
        if ($value === null)
        {
            $this->doesNotExist($key);
        } else
        {
            $this->where[$key] = $value;
        }

        return $this;
    }
public function equalTo ( $ key , $ value ) { if ( $ value === null ) { $ this -> doesNotExist ( $ key ) ; } else { $ this -> where [ $ key ] = $ value ; } return $ this ; }
Set a constraint for a field matching a given value.

@param string $key Key to set up an equals constraint.
@param mixed $value Value the key must equal.

@return AVQuery Returns this query, so you can chain this call.
Set a constraint for a field matching a given value .