Add new network to py-substrate-interface

[yeousunn]

Hi,
I am required to generate an offline extrinsic payload for our network, I am trying to use the py-substrate-interface, for normal query I am able to get the information, however, when I try to generate an extrinsic I am getting error message "Transaction has a bad signature". I think this has something to do with the type_registry_preset in the following:-
substrate = SubstrateInterface(url=host, ss58_format=42, type_registry_preset="development" )

Since the network I am working on is not registered, in the type_registry_preset I am setting as "development".
I read that the types needs to be registered or I need to set the types manually. I am trying to find how to do it, with no success yet.

Can anyone direct me to the right documents?

Edit:-
I found that the registry is stored in https://raw.githubusercontent.com/polkascan/py-scale-codec/v1.0/scalecodec/type_registry/ and locally in the repository py-scale-codec.

How do I generate this type registry for my network?

Thank you,
Yeou Sunn

[arjanz]

Probably you don't need to specify a type_registry_preset, if your network utilises MetadataV14. Before V14, type definitions were required to be administered manually, as described here: polkascan/py-scale-codec#94 (comment)

If the runtime is pre-V14 or there are some exotic changes to the default Substrate implementation, you will need some custom type definitions (or overrides). First you can check if a PolkadotJS type registry JSON file exists, for example for Polymesh there is one maintained here: https://github.com/PolymeshAssociation/polymesh-types/blob/main/polymesh_schema.json

Then you convert the format to match the py-scale-codec format (most different is format for Enum and Struct types) and then you add that JSON file as follows:

custom_type_registry = load_type_registry_file("my-custom-types.json")

substrate = SubstrateInterface(
    url="ws://127.0.0.1:9944",
    ss58_format=42,
    type_registry=custom_type_registry
)
 

Example file for Moonbeam (exceptions are address and signature definitions):

{
  "runtime_id": 900,
  "types": {
    "EthereumAddress": "H160",
    "Address": "EthereumAddress",
    "LookupSource": "EthereumAddress",
    "AccountId": "EthereumAddress",
    "ExtrinsicSignature": "EcdsaSignature"
  }
}

Example for Acala (exception is different MultiSignature definition):

{
  "types": {
    "MultiSignature": {
      "type": "enum",
      "type_mapping": [
        [
          "Ed25519",
          "Ed25519Signature"
        ],
        [
          "Sr25519",
          "Sr25519Signature"
        ],
        [
          "Ecdsa",
          "EcdsaSignature"
        ],
        [
          "Ethereum",
          "[u8; 65]"
        ],
        [
          "Eip712",
          "[u8; 65]"
        ]
      ]
    }
  }
}

[yeousunn]

@arjanz Thank you for the reply,
This helps. I will try it out.
Thank you