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QStandardItem subclassing?

  • hi,
    can any one tell me with a sample code on how to subclass QStandardItem in order to use QStandardItemModel,QtreeView.

  • May I ask you what did you try and what didn't work? (And why do you want to subclass QStandardItem at all?)

  • what did you try and what didn’t work?

  • hi all,
    never mind i got it.

  • Hi, can you please put here a simply code? because i have the same problem as you had

  • How do you know? ManasQt didn't actually describe his problem, nor his solution. I guess the same applies to you as to him: what did you try, and what did not work?

  • Hi Beka,

    The post is more than 1 year old. So for the solution you can post your code.

  • I need to override method of QStandardItem operator<(), but thats not the problem, problem is i dont know how to use myItem in models

  • Did you try just adding your own item instance instead of the standard one? What happened?

  • I have subbclassed QStandardItemModel already, so I just try to set in constructor something like this: this->setItemPrototype(new myItem());

  • You normally should not need to subclass QStandardItemModel itself, you should be able to use it without subclassing.

    Anyway, your call to setItemPrototype should work. However, did you think to reimplement the QStandardItem::clone() method to return an instance of your own class?

  • Yes, I did it, and i debug if it is called, and it works, but my method operator<() is never called

  • I just tried to create two new myItems and compare them, it works, but thats predictable
    but when I called for example myModel->item(r,c)->operator <(other myItem) it isnt called

  • Could you show us the signature for that function from your header? Did you happen to forget the const perhaps?

  • @ bool operator <(const myItem &other) const;
    virtual myItem *clone() const;@

    and, after i setItemPrototype, will it take care of retrieving myItem insted of QStandardItem? or i must reimplement or functions which i am working with?

  • Are you sure about that space between operator < ?

    And yes, thanks to polymorphism, your own function should be called if it actually is an object of your own type. How do you actually set your items? The prototype is just for editing and things like that. How do you fill your model?

  • no, i delete it

    i fill it with functions setItem or setData

  • Show, not tell. It is hard to figure out where the mistake in your code is if you don't show your actual code...

  • yes i know, but the code is really big...
    myModel->setItem( row, column, new myItem(QIcon(icon), "some text") );
    myModel->setData( myModel->index(row, column), "text" );

  • So, extract the relevant sections yourself, or create a small, self-contained example that shows the problem. Also, when posting code, please use @ tags around your code section (I already updated your post in this case) to improve readability.

    Your code, as far as I can oversee it, looks fine to me. I have no idea why it should fail.

  • Okay thank you, i try to override some other methods on model, which can be the problem, and if it wont wors, i paste the code

  • I have one more question, if I override operator<() will it be called by QStandardItem::sort() ?? because i was said to override operator<() to sort like we want, but would be it ever called from sort() ??

  • It should be called from there yes. It is the whole point of the function being there and being virtual.

  • I dont know how to reimplement method item, that it will return myItem, i looked into the sourcecodes, but i dont know what to do... a just think about copy data from myModel->item(r,c); but the method return the pointer, and i will then dont return the exact pointer
    @QStandardItem *QStandardItemModel::item(int row, int column) const
    Q_D(const QStandardItemModel);
    return d->root->child(row, column);

    and i think about the reimplementing the setItem, because i dont know either how to do it :(
    i dont know what to do... sources doesnt help me much, that are so many functions i cant use

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