Fetch a cell value from power table to a Dropdown box

I’m creating a simple database editor. To update a selected row, i’m fetching selected row values to text fields/numeric fields and dropdown box using “try” syntax in expressions. But i failed to fetch value to dropdown box.
I need dropdown box to have fixed set of values (single column with String 1 and String 2), when I fetch value from power table it will be either of these strings and if need to change user click dropdown to choose other string.
Please advise a method for this.