How can we enforce unique values based on more than one column in list

Question

I am unable to enforce unique values based on more than one column in list.

Current scenario: I can make a enforce unique values entered in single column unique using OOTB functionality.

What I want to do: I have two column in a list. I want to assure the combination of values from both these columns is be unique. for Example:

Item 1: column1 = "T1" and column2 = "abc"

Item 2: column1 = "T1" and column2 = "cde"

Item 3: column1 = "T1" and column2 = "abc"

For item 3, user should be prompted with a validation and should not be allowed to enter this combination.

What approach should I use?

Answer 1

I have resolve this issue by using Rest API and first we get the data from list and then we have will use that data on the insert and edit form where inserted data is correct or not.

Note: WBS is lookup column

UserName is person and group column

/_api/web/lists/getbytitle('ListName')/Items?"+"$select=WBS/Title,UserName/Title"+"&$expand=WBS,UserName

Answer 2

On click of Save button , you need to insert PreSaveAction function. In this function you can check for similar combination of column values. if similar combination found, return false. If not, then return true and allow the item to be saved. More information on PreSaveAction() - here