Using custom datum for `mustPayToOtherScript` in off-chain code

Question

Lets say I on-chain i have a Datum like so:

data RandomDatum = RandomDatum {
   { tn :: !TokenName
   , cs :: !CurrencySymbol
   , nn :: !Integer
   } deriving (Show)

Off chain I'm trying to form and submit transaction with:

...
let dat = RandomDatum { 
       tn = ""
     , cs = ""
     , nn = 1
    }
    constraints = Constraints.mustPayToOtherScript vh dat val

ledgerTx <- submitTxConstraintsWith lookups constraints

But my compilation always fails, because dat is not of type Datum. I have also tried:

constraints = Constraints.mustPayToOtherScript vh (Datum $ PlutusTx.toBuiltinData dat) val

Question

How could I convert RandomDatum imported from my on-chain code file?

Answer 1

As far as I know your datum types are required to conform the Data type. Try:

PlutusTx.makeIsDataIndexed ''RandomDatum [ ('RandomDatum, 0) ]

{...}
let randomDatum = RandomDatum { ...params... }
    tx          = mustPayToTheScript randomDatum $ Ada.lovelaceValueOf amount
{...}

Answer 2

Problem was I didn't provide correct type to submitTxConstraintsWith call.

If this was code from Plutus Pioneer Program week one where there is a definition:

data Auctioning
instance Scripts.ValidatorTypes Auctioning where
    type instance RedeemerType Auctioning = AuctionAction
    type instance DatumType Auctioning = AuctionDatum

Call should look like this:

ledgerTx <- submitTxConstraintsWith @Auctioning lookups constraints

Also datum needs deriving (Show, Generic, ToJSON, FromJSON) for serialization

data RandomDatum = RandomDatum {
   { tn :: !TokenName
   , cs :: !CurrencySymbol
   , nn :: !Integer
   } deriving (Show, Generic, ToJSON, FromJSON)