How to get data from a "packed_transaction"?

Question

I am trying to extract the data out of a packed transaction. Specifically, I am reading a proposal from the eosio.msig table and trying to get the data from the proposed multisig transaction to validate it.

Here's the code

   eosio::multisig::proposals proptable( "eosio.msig"_n, proposer.value );
   auto& prop = proptable.get( proposal_name.value, "proposal not found" );

where now prop.packed_transaction holds the packed transaction.

I think I might need to use prop.packed_transaction.data() but I am not sure what this is returning and I can't find any documentation.

Answer 1

Here is an example reading token transfer data out of a transaction

void myaction() {

   struct token_transfer {
      name from;
      name to;
      asset quantity;
      string memo;
   };

   // transaction is inside "prop" object (that we get from a eosio.msig table)
   eosio::multisig::proposals proptable( "eosio.msig"_n, proposer.value );
   auto& prop = proptable.get( proposal_name.value, "proposal not found" );

   // get the first action in the transaction, remember transactions can have multiple actions
   eosio::action my_action = eosio::unpack<eosio::transaction>( prop.packed_transaction ).actions.front();

   // get the data out of the action
   token_transfer my_action_data = my_action.data_as<token_transfer>();

   const name from      = my_action_data.from;
   const name to        = my_action_data.to;
   const asset quantity = my_action_data.quantity;
   const string memo    = my_action_data.memo;
}

Answer 2

Havn't tried myself but i think you can use one of the Unpack<T>(...)-functions from datastream-library - as long as you know Type T.

something like the following:

auto unpackedProposal = unpack<knownProposalType>( prop.packed_transaction.data );