Transactions

Solana has two kinds of transactions: “legacy” transactions represented by the Transaction class and versioned transactions represented by the VersionedTransaction class. These examples will focus on versioned transactions which are what you should use if you have a choice.

These examples do not demonstrate sending transactions or fetching the latest blockhash, which you can do with the send_transaction and get_latest_blockhash methods in solana-py.

Sending SOL

Here we construct a transaction with one instruction - it sends SOL from one wallet to another via the System Program:

from solders.hash import Hash
from solders.keypair import Keypair
from solders.message import MessageV0
from solders.system_program import TransferParams, transfer
from solders.transaction import VersionedTransaction

sender = Keypair()  # let's pretend this account actually has SOL to send
receiver = Keypair()
ix = transfer(
    TransferParams(
        from_pubkey=sender.pubkey(), to_pubkey=receiver.pubkey(), lamports=1_000_000
    )
)
blockhash = Hash.default()  # replace with a real blockhash using get_latest_blockhash
msg = MessageV0.try_compile(
    payer=sender.pubkey(),
    instructions=[ix],
    address_lookup_table_accounts=[],
    recent_blockhash=blockhash,
)
tx = VersionedTransaction(msg, [sender])

Partial signing

Suppose you have a transaction that both Alice and Bob need to sign, and Bob doesn’t want to give Alice his keypair because last time he did that all his apes got stolen.

One solution is for Alice to create a transaction containing her signature and a dummy signature using the NullSigner class. She then serializes this transaction and sends it to Bob, who deserializes it and replaces the dummy signature with his own signature:

from solders.hash import Hash
from solders.instruction import AccountMeta, Instruction
from solders.keypair import Keypair
from solders.message import MessageV0, to_bytes_versioned
from solders.null_signer import NullSigner
from solders.pubkey import Pubkey
from solders.transaction import VersionedTransaction

keypair0 = Keypair()
keypair1 = Keypair()
ix = Instruction(
    Pubkey.new_unique(), b"", [AccountMeta(keypair1.pubkey(), True, False)]
)
message = MessageV0.try_compile(keypair0.pubkey(), [ix], [], Hash.default())
# sign with a real signer and a null signer
signers = (keypair0, NullSigner(keypair1.pubkey()))
partially_signed = VersionedTransaction(message, signers)
serialized = bytes(partially_signed)
deserialized = VersionedTransaction.from_bytes(serialized)
assert deserialized == partially_signed
deserialized_message = deserialized.message
# find the null signer in the deserialized transaction
keypair1_sig_index = next(
    i
    for i, key in enumerate(deserialized_message.account_keys)
    if key == keypair1.pubkey()
)
sigs = deserialized.signatures
# replace the null signature with a real signature
sigs[keypair1_sig_index] = keypair1.sign_message(
    to_bytes_versioned(deserialized_message)
)
deserialized.signatures = sigs
fully_signed = VersionedTransaction(message, [keypair0, keypair1])
assert deserialized.signatures == fully_signed.signatures
assert deserialized == fully_signed
assert bytes(deserialized) == bytes(fully_signed)