src/League/Monga/Query/Projection.php
public function alias($field, $alias)
    {
        $this->fields[$alias] = $this->prepareField($field);

        return $this;
    }
public function alias($field, $alias)
    {
        $this->fields[$alias] = $this->prepareField($field);

        return $this;
    }
public function alias ( $ field , $ alias ) { $ this -> fields [ $ alias ] = $ this -> prepareField ( $ field ) ; return $ this ; }
Sets an alias for a field.

@param string $field The field's name
@param string $alias The field's alias

@return object $this
Sets an alias for a field .