Transactions

Keys in bitcoinpython allow 2 ways of handling transactions: a create_transaction() method that creates a signed transaction and returns the aforementioned transaction in hex, and a send() method that does the same thing but will attempt to broadcast the transaction, returning instead the transaction id for future lookup. Both methods take the exact same arguments.

Outputs

The only required argument is a list of outputs.

>>> key.create_transaction([('bitcoincash:qqrxvhnn88gmpczyxry254vcsnl6canmkqgt98lpn5', 190, 'jpy')])

Output Format

Each output should be a tuple of arity 3 in the form (destination, amount, currency). The amount can be either an int, float, or string as long as it is a valid input to decimal.Decimal. The currency must be supported.

Change Address

Whenever you spend an unspent transaction output, it must be used in its entirety.

Say for example you had this UTXO:

Unspent(amount=55000, ...)

If you wanted to use 35000 satoshi to buy ice cream, you need to use all 55000 satoshi in the transaction. How this works is whatever is left over you send back to yourself as change.

By default bitcoinpython will send any change to the same address you sent from. You can specify where leftover funds go like this:

>>> key.create_transaction(..., leftover='some_address')

Whatever funds remain at this point (remaining = unspent - (sending + leftover)) will be collected by miners as a fee.

Fee

“Miner fees are a small amount of digital currency that is included in transactions as a reward/incentive to the people who operate the network. They help the network continue to grow and provide an incentive for your transactions to be verified quickly.”

—Coinbase

You can change the satoshi per byte fee like so:

>>> key.create_transaction(..., fee=70)

For more information about transaction fees read this.

Unspent Consolidation

By default bitcoinpython will use all of your available UTXOs to make future transactions smaller and therefore reduce fees.

If you don’t desire this behavior and only wish to use what is needed, do this:

>>> key.create_transaction(..., combine=False)

For example, if your had the following UTXOs available:

Unspent(amount=100, ...)
Unspent(amount=200, ...)
Unspent(amount=300, ...)

Forgetting about fees for the moment, assume you want to spend 150 satoshi. If you combine all funds, you’d be left with:

Unspent(amount=450, ...)

If you don’t, you’d be left with:

Unspent(amount=150, ...)
Unspent(amount=300, ...)

Transfer Funds

If you want to send all available funds to another address or wish to simply move your coins, you can specify a leftover address and zero outputs like so:

>>> key.create_transaction([], leftover='some_address')

Unspent

If you already have a means of communicating with the blockchain, you can supply your own list of unspent transaction outputs by doing either:

>>> key.unspents = [Unspent(...), Unspent(...), ...]
>>> key.create_transaction(...)

or

>>> unspents = [Unspent(...), Unspent(...), ...]
>>> key.create_transaction(..., unspents=unspents)

Each item must be an instance of Unspent.