failing contract with long value

[reitcircles]

`from opshin.prelude import *

@DataClass()
class Sdatum(PlutusData):
contentUrl: bytes
contentHash: bytes

def validator(datum: None, redeemer: None, context: ScriptContext) -> None:
sig_present = True
assert sig_present`

If we put
contentHash = b"2584a0f44df3cbe6ebabd17fe0ede414a63c80e1c38a5df3d44557e78e3808ed6220240dfd12644c2255cbeb1800f9d682786ff19f92c44134a3ad3bff7d323e" (blake2 hash value)
it FAILS.

While:
contentHash=b'9da99041a754b0b5708a25c6fc07624c' (md5 hash)

it PASSES

Does anyone have a clue why this is ?

[nielstron]

You are not using the content hash in the contract at all, so I can not help you based on the provided code. Please show where in the contract the hash is being used.

[reitcircles]

Hi Niel,
I use that in the pycardano transaction as such:
Sdatum(contentUrl=contentUrl, contentHash=contentHash )

& then include it in the transaction:

TransactionOutput(address=registry_address, amount=Value(2000000, ref_nft), datum=self.datum)

That is all.

[1000101]

Hey @nielstron, first of all, thanks for using Blockfrost internally. Do you think it would be possible to properly catch & propagate the error messages from the SDK / Blockfrost so that user would know what's going on? Blockfrost is basically just relaying messages from Ogmios and keeping its format, so it might be helpful for users. The tricky part is that Ogmios always responds with 200 and JSON with fault field which specifies the error, so it's not possible to distinguish just by the HTTP code.

[nielstron]

@1000101 this question goes to @cffls who implemented the blockfrost backend in pycardano. sounds doable :)

[cffls]

Pycardano uses blockfrost python SDK to interact with blockfrost: https://github.com/Python-Cardano/pycardano/blob/main/pycardano/backend/blockfrost.py#L288 If there is any error in the result returned by blockfrost, it would show up in the exception.

[slowbackspace]

Hi @cffls, it seems that the error @reitcircles posted 'Namespace' object has no attribute 'result' points to a problem with the parsing of the response in pycardano itself. Blockfrost Python SDK, in this case, only sends a POST request and converts the response JSON to python object.

I think the problem with the error propagation from Blockfrost/Ogmios is that pycardano expects that result field is always present in the response. That is not correct assumption.
https://github.com/Python-Cardano/pycardano/blob/main/pycardano/backend/blockfrost.py#L288

For example, when sending invalid CBOR to evaluateTx endpoint, the error returned from Ogmios has following format

{
  type: 'jsonwsp/fault',
  version: '1.0',
  servicename: 'ogmios',
  fault: {
    code: 'client',
    string: 'Invalid request: Deserialisation failure while decoding serialised transaction. CBOR failed with error: DeserialiseFailure 0 "expected tag".'
  },
  reflection: { id: '...' }
}

Fixing this most likely won't solve @reitcircles's problem, but it could point us in the right direction.

[cffls]

Thanks @slowbackspace. This is very helpful. I guess we can wrap the entire response from blockfrost sdk in the exception when result field doesn't exist in the response.

[reitcircles]

ok. Any examples for ogmios that we can use ? thanks.

…

On Sat, Jul 22, 2023 at 3:44 AM Jerry ***@***.***> wrote: I would suggest trying with Ogmios chain context and see if it gives more info. Or raise a ticket to blockfrost with reproducible steps. — Reply to this email directly, view it on GitHub <#230 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXPVZFTCK3HI5ZH2AXWA4D3XRMWAPANCNFSM6AAAAAA2QMB354> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[nielstron]

Just put the ogmios context as a drop in replacement for the blockfrost context.

You can use the config described in the OpShin-pioneer-program