Accessing nested table in the Plugin through boss hiearchy

OwnedItemDataList ownedItems;
Utils<ITextUtils>()->CollectOwnedItems(pTextModel, 0, pTextModel->GetPrimaryStoryThreadSpan(), &ownedItems);
DebugClassUtilsBuffer className;

for (auto& ownedItem : ownedItems)
{
	if (ownedItem.fClassID == kInlineBoss)
	{
		auto ownedItemUID = ownedItem.GetInlineID();
		UIDRef ownedItemUIDref(pTextBoxRef.GetDataBase(), ownedItemUID);

		InterfacePtr<IHierarchy> nestedMcTextFrame(ownedItemUIDref, UseDefaultIID());
		CHECK_BREAK(nestedMcTextFrame);

		InterfacePtr<IHierarchy> graphicFrameHierarchy(nestedMcTextFrame->QueryChild(0));
		CHECK_RETURN(graphicFrameHierarchy);
		
		auto nestedGraphicsFrameRef = ::GetUIDRef(graphicFrameHierarchy);
		auto isGraphicFrame = Utils<IPageItemTypeUtils>()->IsGraphicFrame(nestedGraphicsFrameRef);
		// true

		InterfacePtr<IHierarchy> nestedTextFrameHierarchy(graphicFrameHierarchy->QueryChild(0));
		CHECK_RETURN(nestedTextFrameHierarchy);
		auto nestedTextFrameRef = ::GetUIDRef(nestedTextFrameHierarchy);
		auto classIDNestedTextFrame = ::GetClass(nestedTextFrameHierarchy);
		auto isTextFrame = Utils<IPageItemTypeUtils>()->IsTextFrame(nestedTextFrameHierarchy);
		// true
		
		// hopefully now I am at the nested text frame that has the table

		InterfacePtr<ITextModel> textModel(nestedTextFrameHierarchy, UseDefaultIID());
		// null
		InterfacePtr<ITableModel> tableModel(nestedTextFrameHierarchy, UseDefaultIID());
		// null
		InterfacePtr<IMultiColumnTextFrame> nesteddMCTextFrame(nestedTextFrameHierarchy, UseDefaultIID());
		// null
		InterfacePtr<ITextFrameColumn> nesteddMCTextFrame2(nestedTextFrameHierarchy, UseDefaultIID());
		// null
	}
	else if (ownedItem.fClassID == kTableFrameBoss)
	{

		////this is table
		//InterfacePtr<ITableFrame> iTableFrame(db, ownedItems[i].GetInlineID(), UseDefaultIID());
		//if (!iTableFrame)
		//	break;

		//InterfacePtr<ITableModel> iTableModel(iTableFrame->QueryModel());
		//if (!iTableModel)
		//	break;
	}
}

The SDK has more page item types (boss classes) than scripting.

kInlineBoss is one of those page item types, meaning its boss class is based on kPageItemBoss.

As a boss class, it has many interfaces - different methods and properties.

Instances of page item are arranged in hierarchies, meaning they have an interface IHierarchy.

The purpose of the kInlineBoss is to be the root of one hierarchy, anchored as owned item within a text model.

It implements the concept that any page item can get inlined, so that the page item and most other page item related code need not deal with the text model. Therefor you don't see it in the dump / screenshot above, owned items are not covered by that trace. I don't know which might that be, I'm wading thru 445,720 lines produced by an own utility instead.

Whatever comes below can vary - be it a group, an image or another text frame.

You have to descend the hierarchy, look at the child.

For that you query the IHierarchy of the kInlineBoss, as you do with the variable named nestedMcTextFrame . I'd name it ownedItemHierarchy instead following the other names you chose for that boss. Or name all of them "inline…", starting from your ownedItemUID where you already know the boss class is kInlineBoss.

As you say that the "nestedMcTextFrame" interface is null (really?), there must be something wrong, we can stop looking beyond. My guess would be you're using the wrong database, from your pTextBoxRef whose whereabouts are missing in your code snippet. Is it your output variable? Use ::GetDataBase(pTextModel) instead.

Getting further down: Ah, I see, actually "nesteddMcTextFrame" is null, too similar thus confusing name.

Now look at the child. You only know it is one of those page item bosses. Instead of all your IPageItemTypeUtils tests, use DebugClassUtilsBuffer to determine which. Should be kSplineItemBoss*, the shape surrounding the text frame with its columns. It could be the same for blank rectangles or others. Continue descending the hierarchy to get to the nested text frame, that would be kMultiColumnItemBoss, then even deeper the kFrameItemBoss - a column. Same as with your screenshot above.

* with all that nesting one can get easily lost, in DM I wrongly suggested the child of kInlineBoss was already the kMultiColumnItemBoss. Also be prepared that other InDesign features can optionally add other levels within the hierarchy. IHierarchy has a call so you can ignore most of that nesting, GetDescendents lets you deep-search for an interface such as IID_IMULTICOLUMNTEXTFRAME .

Unlike the spline, both kMultiColumnItemBoss and kFrameItemBoss are already part of the nested text frame as known from scripting - the actual frame and a column. So you'd take the earliest chance to determine the (nested) story, using kMultiColumnItemBoss:IMultiColumnTextFrame.

Since the text story is a different boss object (boss class is kTextStoryBoss), you can't just feed the MCTF boss into an InterfacePtr, instead you have to use one of the Query or Get methods in the interface.

Now you have to find the table within the nested story. Knowing it is an owned item you can again use CollectOwnedItems, but I'd use interface kTextStoryBoss:ITableModelList instead.