Multi LookUp - Check for unique values

0
votes

I´m trying to set up unique values in my PowerApp-Form. The data is stored in a Sharepoint list. I have a column called watches, items in this column have a unique number, which have to be unique. People can pick multiple of those watches in a LookUp-field. But before submitting the form, I need to check if those picked values already exist in my list and at least display an error message.

I have setup a regular text field and added following rule to it: 

If(LookUp(MyList.Watches;DataCardValue4.SelectedItems.Value in Watches;"OK")<>"OK";"No Error";"Watch already exist")

DataCardValue4 is my LookUp field, where people can pick those watches. With this rule I want to check if a item already is in my column watches and let my text field display the error. Somehow the rule doesn´t work.

Can you tell me how I compare multiple lookup choices to my table/column entries?

1
sharepointpowerapps

1 Answers

0
votes

The first parameter to the LookUp function should be the table (SharePoint list) rather than the column. So the first parameter should be 'MyList' rather than 'MyList.Watches'. Also, I'm not sure that the formula provided (second parameter to LookUp) will work. In your formula, you will be looking for multiple items (DataCardValue4.SelectedItems.Value) within multiple items (Watches). Perhaps you can update your app to have users only pick one watch value before submitting?

One last thing to note. I'm not sure how big you expect your SharePoint list to get, but I would highly recommend keeping your LookUp formula within the bounds to support delegation. More specifically, SharePoint has different formula requirements than other connectors. For example, you can use '=' in your formula, but not 'in'.

Your new rule might look something like below. Please note that it could have syntax errors and might not even be delegable in it's current form since I am providing the rule with no checking. Also, I switched from using LookUp to using Filter instead just because I'm more familiar with Filter. However, both functions are very similar.

If(CountRows(Filter(MyList; DataCardValue4.Selected.Value = Watches)) > 0; "Watch already exist"; "No Error")