I started creating this python library with most of the Plutus types represented as classes. I get their values by calling the json method, which returns the JSON equivalent of this type so it can be passed to cardano-cli, like the following:

class PubKeyHash(object):
    def json(self):
        return json.dumps({
            "bytes": self.__pkh

This worked well while I was writing these values to files and passing the files path to cardano-cli, but since I'm using ssh to connect to the node and writing files all the time is not very performant, I think it would be great to, instead, pass the JSON values directly.

When I try to do this using the --mint-redeemer-value argument, though, it returns me a weird error Exception: option --mint-redeemer-value: Failed reading: not a valid json value, which makes me assume my JSON is not formatted correctly.

This is the command I'm running:

--mint-redeemer-value {"constructor":0,"fields":[{"constructor":0,"fields":[{"bytes":"
02fbd1c6934d888ec6575de3ec2f87dd75aec2891f20e0dc38fa7440e47a3803"}]},{"int":0}]} \

If it is the case that my JSON is formatted incorrectly, how should I format it? If it is not, can anyone bring me some light on why I'm running into this error?

1 Answer 1


Checking the man page for cardano-cli transaction build, I see:

  --mint-redeemer-value JSON VALUE
                           The JSON value for the script data. Supported JSON
                           data types: string, number, object & array.

This is expecting a basic JSON value (no schema).

Since you are providing JSON that follows the schema for script data, you will need to write your JSON to a file and use --mint-redeemer-file instead:

cardano-cli transaction build \
--mint-redeemer-file my-file.json 

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