How to add nonce to generated (deferred) transcation

Question

Using cleos -f adds a context_fee_action to the TX like so:

  "context_free_actions": [{
      "account": "eosio.null",
      "name": "nonce",
      "authorization": [],
      "data": "1277571574850500"
    }
  ],

Adding a context_free_action to the vector of the TX in the SC gives me an error.

Error Details: context free actions are not currently allowed in generated transactions

Is there a good way to add the nonce? I tried adding it to the packed data tuple after the all needed data but the nonce seem to be ignored. I do not want to adjust the action that I am calling withing the deferred action.

Answer 1

Michael Yeates gave a good suggestions on Telegram. Simply add an action instead of a context_free_action.

A code example would look like this:

auto nonce = getNextId();
txn.actions.emplace_back(eosio::permission_level{_self, "active"_n},
                         "eosio.null"_n,
                         "nonce"_n,
                         std::make_tuple(nonce));
txn.actions.emplace_back(eosio::permission_level{_self, "active"_n},
                         _self,
                         "myaction"_n,
                         std::make_tuple(myarg1, myarg2...));
txn.send(nonce, _self, false);