atk4\data\Join::init PHP Method

    public function init()
    {
        $this->_init();
        // handle foreign table containing a dot
        if (is_string($this->foreign_table) && strpos($this->foreign_table, '.') !== false) {
            if (!isset($this->reverse)) {
                $this->reverse = true;
                if (isset($this->master_field)) {
                    // both master and foreign fields are set
                    // master_field exists, no we will use that
                    /*
                                        if (!is_object($this->master_field)
                       && !$this->owner->hasElement($this->master_field
                                        )) {
                    */
                    throw new Exception(['You are trying to link tables on non-id fields. This is not implemented yet', 'condition' => $this->owner->table . '.' . $this->master_field . ' = ' . $this->foreign_table]);
                    /*
                                        }
                    
                                        $this->reverse = 'link';
                    */
                }
            }
            list($this->foreign_table, $this->foreign_field) = explode('.', $this->foreign_table, 2);
            if (!$this->master_field) {
                $this->master_field = 'id';
            }
        } else {
            $this->reverse = false;
            if (!$this->master_field) {
                $this->master_field = $this->foreign_table . '_id';
            }
            if (!$this->foreign_field) {
                $this->foreign_field = 'id';
            }
        }
        $this->owner->addHook('afterUnload', $this);
    }