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I have a project that was compiled with the Flex 3.2 SDK.

One of my components is a combobox, which is bound to a property (called products) in the Cairngorm model. If I insert a new value into model.products, then the combobox immediately shows the new value. Works perfectly.

I then moved to the 3.5 SDK, and running the identical operation causes a problem. Even though the model has been updated (I have verified that this is definately the case), the combobox does not show the new value correctly - it seems to be aware that there is a new item because there is a new row in the combo, but the new row is blank and unselectable. The existing items in the combo are there and selectable (as they should be). If I re-initialising the form (i.e. close and re-open the TitleWindow on which the combo is located), then all the correct values (including the new one) are shown in the combo.

I have swapped back and forth a few times between 3.2 and 3.5 to verify that this is indeed the root cause.

Any idea on how to get around this would be greatly appreciated.

JonoB
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2 Answers2

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Are you changing the dataProvider, or replacing it?

I have noticed that in the Flex 4 version of the Flextras AutoCompleteComboBox the ComboBox dataProvider sometimes get out of sync with the drop down's dataProvider. I figured this was all my fault due to the changes I made to add AutoComplete to the ComboBox.

It is entirely possible that this change was added in Flex 3.5; and I just didn't notice it until my Flex 4 adventures.

First, I'd try to invalidate the ComboBox when the dataProvider changes. You can do this by listening to the collectionChange event of the collection. In the event handler just do: 

myCombo.invalidateProperties()
myCombo.invalidateDisplayList()

If you're repacing the dataPRovider, then you may try to override the set dataProvider method and add a line like this:

this.dropdown.dataProvider = value;

Is an odd issue. I believe in Flex 3 / 3.2 was that every time the dataPRovider changed the drop down was closed [destroyed] and re-created. It appears they stopped doing that at some point; which causes this anomaly.

JeffryHouser
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  • The dataProvider for the combo was set to a Bindable model (Cairngorm). So, updating the model in the command result automatically bubbled up to the combobox. Well, it used to anyway. Having tested a bit more, it seems that I have to reset the dataprovider: cb_products.dataProvider = model.products; Which kinda sucks. – JonoB Jun 09 '10 at 16:53
  • Actually, the above doesnt work. It seems that cb_products.dropdown.dataProvider = model.products does, however. Which still sucks. – JonoB Jun 09 '10 at 16:59
  • You're replacing the dataProvider with that code. There must be a fringe bug added to the ComboBox somewhere between 3.2 and 3.5 . You can probably extend the ComboBox and override the set dataProvider method to do this update internally so you don't have to do it manually. – JeffryHouser Jun 09 '10 at 17:26
  • Pretty much confirmed to be a bug in 3.5. http://forums.adobe.com/thread/597632 https://bugs.adobe.com/jira/browse/SDK-25705 https://bugs.adobe.com/jira/browse/SDK-25567 I hate having to monkey patch – JonoB Jun 09 '10 at 19:19
  • I luckily already had extended the ComboBox into a custom component, which I use just about everywhere in my app, so it was just a matter of adding the following to my custom component: private var newDropDown:ListBase; override public function set dataProvider(value:Object):void { super.dataProvider = value; newDropDown = dropdown; if(newDropDown) { validateSize(true); newDropDown.dataProvider = super.dataProvider; } } – JonoB Jun 09 '10 at 19:55
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//this will replace the list base on an update
private var newDropDown:ListBase;

//This addresses a bug in flex 3.5 SDK 
//where the list base does reflect changes to the data provider
//forums.adobe.com/thread/597632  
//bugs.adobe.com/jira/browse/SDK-25705 
//bugs.adobe.com/jira/browse/SDK-25567
override public function set dataProvider(value:Object):void
{
    super.dataProvider = value;
    newDropDown = dropdown;

    if(newDropDown)
    {
        validateSize(true);
        newDropDown.dataProvider = super.dataProvider;
    }
}
JonoB
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