i mean using the code to check what the item i will get if i redeem it
It is not supported in the current coupon system. You have to provide the reward details when distributing the codes.
Otherwise, you may need to implement an external database to track the state of coupon. It is OK to generate Coupon from PlayFab, then you need to import them to the database so that player will inquire the coupon status before the redemption.
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