Model/View: Use own class with QVariant

[No-Nonsense]

The Model/View framework uses QVariant to pass data between the Model and the View. This works fine for Qt's own data types, but I want to pass my own data type to the view (the delegate knows how to handle my custom data).

I have subclassed QBitArray and registering MyBitArray using the following code. It just works fine:

Q_DECLARE_METATYPE(MyBitArray);

Q_DECLARE_METATYPE(MyBitArray);

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Now I want to pass two of these custom BitArrays without using two columns (ModelIndeces), as they get edited together (data and mask), so I tried

typedef QPair<MyBitArray, MyBitArray> MyBitArrayPair;
Q_DECLARE_METATYPE(MyBitArrayPair);

typedef QPair<MyBitArray, MyBitArray> MyBitArrayPair;
Q_DECLARE_METATYPE(MyBitArrayPair);

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and

class MyBitArrayPair
{
public:
	MyBitArrayPair() {}
	MyBitArray first;
	MyBitArray second;
};
Q_DECLARE_METATYPE(MyBitArrayPair);

class MyBitArrayPair
{
public:
	MyBitArrayPair() {}
	MyBitArray first;
	MyBitArray second;
};
Q_DECLARE_METATYPE(MyBitArrayPair);

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The compiler does not complain anymore about

MyBitArrayPair pair = value.value<MyBitArrayPair>();

MyBitArrayPair pair = value.value<MyBitArrayPair>();

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but still complains about

case Qt::EditRole: return MyBitArrayPair(x.data(), x.mask());

case Qt::EditRole: return MyBitArrayPair(x.data(), x.mask());

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with the following error message:
"error: conversion from 'MyBitArrayPair' to non-scalar type 'QVariant' requested"
There is a constructor for MyBitArrayPair(first, second) that I omitted here.

What am I doing wrong? How can I pass custom classes using QVariant?

Thanks in advance,
-Jens