Clear Cascading Comboboxes

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Posted on by NicolasRivollet

Hello everyone, an thank you for your support

I have recently discovered Power Apps and I am really excited about the possibilities it offers!

I have followed the instructions from this tutorial : Working with Cascading Lists in SharePoint and Power Apps

And now I have 2 beautiful combo boxes, one where the user can select a Region, the other one where the user can only select a Country from this Region (screenshot below)

Say the user saves an item with Region: "Europe", Country: "France"

Now, what if the user changes his mind, edits this item thanks to the form, but only changes the Region without changing the Country ? Nothing stops him from registering Region: "America", Country: "France" for instance.

Is it possible to clear the value of the "Country" Combo box when the user change the "Region" Combo Box ?

Thank you for your attention and your help,

Cascading Lists

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Building Power Apps

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WarrenBelz 156,528 Most Valuable Professional on at

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Hi @NicolasRivollet ,

You just need to Reset the country box on the OnChange of the Region box. So OnChange of Region

Reset(YourCountryBoxName)

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NicolasRivollet 15 on at

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Hello @WarrenBelz, thank you for your reply!

Yeah i’ve thought about that. Unfortunately what it does is that, if the user is editing an existing item of the SharePoint List, the Reset function sets the Country Combo Box to this existing item’s country, which might not be null.

To makes thinks clear, following the example,
if the user edits the Europe/France Item
changes the country to Canada
then changes the region to Ameria
the reset(countryComboBox) will reverse back the country to France, instead of null

Any other ideas ?

[Edit: grammar]
WarrenBelz 156,528 Most Valuable Professional on at

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Hi @NicolasRivollet ,

That is getting a bit difficult as after a value is changed, Power Apps does not know what was there before unless it is saved somewhere. Clearly if the record is not saved, it will retain the "old" value, You may want to do something like writing to a collection every time the Country is changed (and store the two values) and then on Region change see if there is something matching in the collection to put in Country, but is that worth the effort over simply resetting Country?

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NicolasRivollet 15 on at

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Yeah you are right, I guess that settles it
thank you @WarrenBelz !
regards
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NicolasRivollet 15 on at

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Hello @WarrenBelz

The cleanest way I have found to make sure the user enters adequate data is to set up a Boolean based on the validity of the "Region/Country" selected pair (in pseudo code "Country in Region"), and condition the "OnSave" event of the SharePointIntegration control on that Boolean. And eventually show up an error message for the User.

Regards,