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COMBO BOX OnChange update with incorrect row value to collection

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Posted on by JeffHe Microsoft Employee

My app is a Power App canvas. I develop a combo box in a gallery. The Combo box data source is an API endpoint. I implement an Update formula in combo box OnChange. The Update formula should update the item data of the collection with the selected data id. When run the application, the first row is updated successfully. However, when second row added and combo box updated, the collection item of second row updated with the value of the first row. And the third and so on rows have the same issue.

The update formula is implemented as below, the issue is serviceTreeId is always set with first row combo box selected id. The expected behavior should be serviceTreeId is set with value of the combo box that user updated.

BTW, when I move the Update formula to OnSelect, the data update correctly. However, it has other issue, so it is not a perfect workaround.

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JeffHe Microsoft Employee on at

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Update one information: The Combo box data source is an API Endpoint.
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v-yujincui-msft Microsoft Employee on at

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Hi @JeffHe ,

I have made a test with the Patch() function and it seems that works fine.

1. Here is my data source.
2. Here is the data source for the Combo Box, which is a collection.
3. Select the Combo Box Control and apply the following formula on its OnChange property as:
Patch(datasource,ThisItem,{serviceTreeId:ComboBox2.Selected.id})
Result:

Best Regards,
Charlie Choi
JeffHe Microsoft Employee on at

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Hi, @v-yujincui-msft , thank you for your reply. I tried your solution, I think you have not set "defaultSelectedItems", so I removed the formula of "defaultSelectedItems". Although the collection updated, but the selected value didn't show on the combo box UI. Is there any solution for this?
v-yujincui-msft Microsoft Employee on at

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Hi @JeffHe ,

Here is the configuration of my Combo Box Control. Hope it helps.

Best Regards,
Charlie Choi
JeffHe Microsoft Employee on at

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Hi, @v-yujincui-msft , thank you for sharing. So when Patch or Update used in OnChange, the selected item value didn't show in the combo box. We need to show the selected item in another component. Do my understand correct?
v-yujincui-msft Microsoft Employee on at

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Hi @JeffHe ,

Sorry i am a little confused, could you please share a screenshot of the problem you encountered?
You could change the display text of the Combo Box by editing the Fileds property.

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Charlie Choi
JeffHe Microsoft Employee on at

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Hi @v-yujincui-msft , sorry for confusing. I mean I expect the selected item would be show like below. But actually it didn't show. Can I make it show?
v-yujincui-msft Microsoft Employee on at

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Hi @JeffHe ,

Do you want the Combo Box Control to display the corresponding text by default based on the serviceTreeId of this record?
Maybe you could try to select the Combo Box and apply the formula on its DefaultSelectedItems property like this:
[LookUp(testcollection,ThisItem.serviceTreeId=id).value]

Best Regards,
Charlie Choi
JeffHe Microsoft Employee on at

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Hi, @v-yujincui-msft thank you! I confirm that when use collection as data source there is no problem. But my implementation uses API Endpoint as data source, so that user can search backend data by keyword. The "Items" and "defaultSelectedItems" are both get from API Endpoint. Is there anything I need take care when I use API Endpoint as data source?
v-yujincui-msft Microsoft Employee on at

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Hi @JeffHe ,

Sorry, i don't know what the data you got looks like.
Maybe you could consider saving the data you get from the API Endpoint into a collection and then use it.
In addition, you could try to replace the collection with the data you get from the API Endpoint in the formula i provided.
or

Best Regards,
Charlie Choi