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How can I generate an ID of a transaction before submitting it to an RPC node? I know I can get a transaction signature as a result of web3.sendAndConfirmTransaction call but is it possible to generate the signature deterministically?

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    Transaction IDs on Solana are signatures (signature[0]), not hashes. I'd suggest updating your question to clarify this fact and avoid propagating misinformation
    – trent.sol
    Commented Jul 12, 2022 at 23:25
  • This was supposed to be a question from a person who comes from EVM background (who from my perspective comprise the bigger part of devs coming to Solana). Commented Jul 13, 2022 at 19:33
  • No sense misinforming them. Accuracy is key to understanding
    – trent.sol
    Commented Jul 13, 2022 at 20:21

1 Answer 1

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You can manually sign the transaction before sending it, and then retrieve signature:

const bs58 = require('bs58');

// build a transaction
const transaction = new Transaction(...);

// sign it explicitly
transaction.sign(...signers);

// retrieve the signature as base58
const signature = bs58.encode(transaction.signature())

You will need to already have a blockhash defined and set against the transaction for this to work.

This will not work with sendTransaction, which re-signs everything. So serialize the message directly to send:

const message = transaction.serialize();
connection.sendRawTransaction(message)

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