Combobox, reset value to blank

[miquilenadiego]

Hello!

I'm customizing a sharepoint form and I have.

1. A combobox (called "empresa") which is a lookup column in a sharepoint list pointing to a sharepoint list called "concesionarios". 
2. A drop down input called "Garantia" which have 3 options. (yes, no, lugar)

I need:

A. The combobox disabled every time until the user chooses the option "lugar" in "Garantia" drop down. Working✔️

B. When the user changes the drop down value to "yes" or "no" options, the combobox should change to Disabled and reset the value stored to blank. Not working ✖️

WHAT I'VE DONE SO FAR:

A. To accomplish A, in the combobox DisplayMode property I set: 

DisplayMode = If(GarantiaDataCardValue.Selected.Value <> "lugar", DisplayMode.Disabled, Parent.DisplayMode )

B. This is my problem, if the user changes "lugar" to "yes" or "no" I need the value selected in the combobox value set top blank, null o whatever, for this I tried changing the following properties in the combobox and combobox's datacard.

Combobox:

DefaultSelectedItems = If(GarantiaDataCardValue.Selected.Value = "lugar", Parent.Default, {} )

This supposed to set the value to blank. It is just working in the form, but no in the list view where I can see the previous value stored in the combobox

combobox's datacard:

Update = If(GarantiaDataCardValue.Selected.Value = "lugar", comboboxDataCardValue.Selected, {})

This should update the value of the combobox but it's not working, if I edit the record again and if a I choose "lugar" again in the dropdown, it shows the previous value stored in it.

I think i'm missing something between the properties DefaultSelectedItems and Update.

Any help would be appreciated, thanks.

[Anonymous]

To remove a user's input and reset a control to the default selection, you can use Reset()

[miquilenadiego]

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@Anonymous wrote:

To remove a user's input and reset a control to the default selection, you can use Reset()

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Hello @Anonymous  I tried but it returns this message

Behaviour function in a non-behaviour property.
You can't use this property to change values elsewhere in the app

[Anonymous]

This function will have to be in an action property, such as OnSelect, OnChange, OnVisible, etc.. This error is saying you're using it in a Text property, or something similar.

[miquilenadiego]

Ok, but how can I change those properties? Sorry I'm still a newbie

Do I have to change them in the Dropdown instead of the combobox? DefaultSelectedItems is ok and don't have to change Update?

[Anonymous]

Here's a quick little example with a dropdown:

See the Items property here is an example table with 3 rows in the 'Test' column. The values are Value1, Value2, and Value3.

Now, the same Dropdown has an OnChange property, where you can call actions. If you select Value2, it resets, otherwise it notifies the user which item they've selected.

These actions can be done when a dropdown is changed, or when a button is pressed, or a gallery item is selected, etc...

[v-yutliu-msft · Accepted solution]

Hi @miquilenadiego ,

Pleas try this:

1)set the drop down's OnChange:

If(GarantiaDataCardValue.Selected.Value="lugar",Set(var,"a"),Set(var,"b"));If(var="b",Reset(empresaDataCardValue)

 2)set the combo box's DisplayMode:

If(var="a",Parent.DisplayMode,DisplayMode.Disabled)

 set the combo box's DefaultSelectedItems:

{}

 set the combo box's datacard Update:

comboboxDataCardValue.Selected

//based on the selection of drop down, the variable's value will change. If the variable is "a", then the combo box's mode will become enabled. If the variable is "b", the combo box will be reset. If the combo box's DefaultSelectedItems is {}, then the combo box's DefaultSelectedItems will display as empty. No matter what the combo box display, the update value could always be represented as "comboboxDataCardValue.Selected"

What's more, Reset is behavior function, you could only set this function in behavior property, like OnChange.

If you want to update blank value to data source, you also need to turn this setting on:

 Or else, if you update with  blank value, the data will not be updated successfully. It will retain the original data.

Best regards,

[miquilenadiego]

Thank you @v-yutliu-msft ! Your solution is close to what I need and It's what I was trying after Eric recommendations. 

But the problem is that Reset() doesn't "clear" the combobox it just sets it to the default value of the combobox and it appears in the sharepoint list view, so that I modified the second "IF" in the ON CHANGE property:

If(GarantiaDataCardValue.Selected.Value="lugar",Set(var,"a"),Set(var,"b"));If(var="b",empresaDataCardValue.Selected.Value = "-")

but it doesn't work either. I also created a "-" record in the sharepoint list "concesionarios" but it didn't work either. 

The second problem is that although I set DefaultSelectedItems to {} the form continues updating the combobox value that the user chose before (when  the drop down was equal to "lugar"), if i keep DefaultSelectedItems = Parent.default at least the user can delete that value before changing the dropdown from "lugar" to "yes" or "no" 

[miquilenadiego · Accepted solution]

Hi @v-yutliu-msft I could make it work (with your help of course) I changed DefaultSelectedItems from "{}" to "[]" and now it works along with Reset(empresaDataCardValue)

Do you have any idea about what's the difference between using "{}" and "[]" ?

I found this within the documentation

For example, [ 1, 2, 3, 4 ] is equivalent to

Table( { Value: 1 }, { Value: 2 }, { Value: 3 }, { Value: 4 } ) 

https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/working-with-tables

[Anonymous]

Reset() works like a charm 😁😊