Psbt class can parse and generate a PSBT binary based off of the BIP174.
There are 6 roles that this class fulfills. (Explained in BIP174)
Creator: This can be done with
Updater: This can be done with
psbt.addOutputs(outputs) when you are looking to
add new inputs and outputs to the PSBT, and
addInput requires hash: Buffer | string; and index: number; as attributes
and can also include any attributes that are used in updateInput method.
addOutput requires script: Buffer; and value: number; and likewise can include
data for updateOutput.
For a list of what attributes should be what types. Check the bip174 library.
Also, check the integration tests for some examples of usage.
Signer: There are a few methods. signAllInputs and signAllInputsAsync, which will search all input
information for your pubkey or pubkeyhash, and only sign inputs where it finds
your info. Or you can explicitly sign a specific input with signInput and
signInputAsync. For the async methods you can create a SignerAsync object
and use something like a hardware wallet to sign with. (You must implement this)
Combiner: psbts can be combined easily with
psbt.combine(psbt2, psbt3, psbt4 ...)
the psbt calling combine will always have precedence when a conflict occurs.
Combine checks if the internal bitcoin transaction is the same, so be sure that
all sequences, version, locktime, etc. are the same before combining.
Input Finalizer: This role is fairly important. Not only does it need to construct
the input scriptSigs and witnesses, but it SHOULD verify the signatures etc.
psbt.finalizeAllInputs() please run
Running any finalize method will delete any data in the input(s) that are no longer
needed due to the finalized scripts containing the information.
Transaction Extractor: This role will perform some checks before returning a
Transaction object. Such as fee rate not being larger than maximumFeeRate etc.