[Qt-interest] Select index of comboBox with item Data (ID)

[Malyushytsky, Alex]

Whatever you call it item data is just data associated with item in combobox.

To support operation you are looking for ("->selectItem(variantID);"  )
it would have to either  call " myCombo->findData(variantID)" itself or
keep map (extra memory/time to keep it updated) which will provide quick way to find item data by index.

Second approach will slow down the normal usage and increase memory requirements.
So I think reasons it is not done by default are clear.

In the most cases findData will be fast enough unless you call it too often, in this case you might want to reconsider your design.
First I would recommend to check if using findData gives you any visible delay.

If you really need very fast access to item by data
create QMap or QHash  with data as a key and index as value.

Regards,
   Alex



-----Original Message-----
From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Matthias Pospiech
Sent: Sunday, June 27, 2010 1:40 PM
To: Qt Interest
Subject: [Qt-interest] Select index of comboBox with item Data (ID)

I can use the userData of a comboBox to save IDs together with the display text.
I can set these IDs using either

myCombo->setItemData(i, variantId);

or
myCombo->addItem("Text", variantId);

I can get the ID for a known index using

QVariant variantId = myCombo->itemData(myCombo->getCurrentIndex());

But how do I select the index using an ID?
Is this the only option?

myCombo->setCurrentIndex(myCombo->findData(variantID));

I am asking because I would have expected something like

myCombo->selectItem(variantID);

Matthias



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