Patch function suddenly behaving strangely with collection

[AndrewCrompton]

I am using Patch to modify records in a collection, and code that previously worked ok has just started producing strange behaviour.

The collection, called collMembers, has a column called Chosen, which takes true / false values, and I want to be able to set / unset Chosen for individual records or for an entire set of records.

I have a gallery that lists the records in the collection. Each item in the gallery has a check-box which is used to set / unset Chosen for that item. The OnCheck property for the check-box does what you'd expect: 

Patch(collMembers, ThisItem, {Chosen: true}) ;

This works.

I also have a button with code that sets every item in the gallery to Chosen = true. The gallery is called BrowseGallery1_1 and the button's OnSelect property is:

ForAll(BrowseGallery1_1.AllItems As ThisOne,
    Patch(collMembers, ThisOne, {Chosen: true})
);

This was working fine, until - without me (knowingly) having made any change that would affect things - it began to produce strange behaviour. Instead of modifying the existing records in the collection, the patch function is now adding new records: if BrowseGallery1_1 initially has 12 items, then then the patch creates 12 new records in collMembers.

I cannot see these new records - they are not shown in the gallery - but I have a label displaying the number of records in the gallery and that increases by 12. The new records have Chosen = true (I have a counter for that too). The existing records seem to remain unchanged: their check-boxes are not checked in the way they should be.

I have noticed similar new behaviour in other cases where I have used the patch function: instead of modifying existing records in a collection (as it previously did), it now creates new records, when used within a ForAll. 

Has anyone else noticed anything similar? And found a solution?

Thank you in advance for any suggestions.

[RandyHayes]

@AndrewCrompton 

You might be interested in reviewing this post.

In the end, it seemed that moving from the Patch to the UpdateIf solved the issue.

I hope this is helpful for you.

[AndrewCrompton]

Thanks, Randy. I'll give UpdateIf a try, and we'll see what happens.

[RandyHayes]

@AndrewCrompton 

You will not be able to use the ThisItem identifier with UpdateIf, but instead use a unique identifier in your list.

[Anonymous]

Hi, do yall know how to generate a unique id like a,b,c once button is clicked.

The delivery id generated will be used in another sharepoint list.

The id column used is Delivery_ID.

How to amend the codes below? Thanks.

SendEmailv2.Run(JSON(colOrderItems));

// insert new row for each product into SharePoint list
ForAll(
colOrderItems,
Patch(
OrderList,
Defaults(OrderList), {
Memory: Memory,
Storage: Storage,
Title: Title,
Quantity: Value(Quantity),
Price: Value(Price),
'TotalPrice (TotalPrice0)': TotalPrice,
Image: Image,
Dept: Dept,
Division: Division,
DeliverLocation: DeliverLocation,
'28ByteCode': '28 Byte Code',
Product: ProductFinal,
Processor: Processor,
DesktopAddon: DesktopAddon,
Remarks: Remarks
}
)
);

Notify("Order was successfully submitted", NotificationType.Success);