Silverstripe DataObject Relationships - 两个has_many彼此相关

Question

I am going a little nuts trying to figure this out, I am sure the solution is simple, but I have real trouble visualising these data relationships. So, here's what I am trying to do:

I have an object called "Offer", which needs two GridFields for "ItineraryItem" and "ItineraryTab" Data Objects

This is what I have at the minute in the three objects, but it is returning an error every time and I can't seem to figure out why.

// Offer
$has_many = array(
   "ItineraryItems" => "ItineraryItem",
   "ItineraryTabs" => "ItineraryTab"
);

// On ItineraryTab
$has_one = array(
   "Offer" => "Offer"
);
$many_many = array(
   "ItineraryItems" => "ItineraryItem"
);

// on ItineraryItem
$has_one = array(
   "Offer" => "Offer"
);
$belongs_many_many = array(
   "ItineraryTabs" => "ItineraryTab"
);

As I said, the solution is probably pretty simple, but I can't see it anymore after so many hours of trying! Please help me!

I am operating on Silverstripe 3.4, if that helps

Answer 1

So, i had to answer this myself, and found something that works -- but i am not sure it is the correct way or if it's a hack. Here it is anyway, in case it helps someone.

First off, i had to get into the database and delete the OfferID column from the Tab object.

// Offer.php
$has_many = array(
    'ItineraryItems' => 'ItineraryItem'
);

$many_many = array(
   'ItineraryTabs' => 'ItineraryTab', 
);

//ItineraryItem.php
$has_one = array(
    "Offer" => 'Offer'
);

$many_many = array(
    'ItineraryTabs' => 'ItineraryTab'
);

//ItineraryTab.php
$belongs_many_many = array(
    "ItineraryItems" => "Offer.ItineraryItems"
);

If anyone finds something more elegant, please let me know, but this seems to do the job for now.