Reading Ledger State with the Walley Python SDK

w.ledger reads the Canton ledger through Walley’s authenticated proxy. It is the Python twin of the dApp SDK’s ledgerApi. Common reads are named methods so you don’t need to know ledger endpoints; a raw passthrough covers everything else. The SDK’s bearer token is attached automatically.

Active contracts

The read you’ll reach for most, typically to feed contract ids into your dApp’s commands:

for c in w.ledger.active_contracts():
    print(c.contract_id, c.template_id, c.payload)

Filter by template. Both id forms work, the package-id form and the package-name form:

w.ledger.active_contracts(
    template_ids=["#splice-amulet:Splice.AmuletRules:TransferPreapproval"])

w.ledger.active_contracts(
    template_ids=["6c5802f8...:Splice.AmuletRules:TransferPreapproval"])

Each ActiveContract lifts the useful fields out of the ledger’s nesting:

c.contract_id      # feed into your dApp's exercise commands
c.template_id      # <package-id>:Module:Entity
c.payload          # the contract's create arguments (dict)
c.created_event    # the raw ledger createdEvent, for anything else

By default the query runs as the client’s party at the current ledger end; override with party_id=, at_offset=, or verbose=True.

Raw passthrough

For anything the named methods don’t cover, forward requests directly. The path is the JSON Ledger API resource:

w.ledger.get("/v2/users")
w.ledger.post("/v2/updates/flats", json={...})
w.ledger.request("GET", "/v2/state/ledger-end")

The proxy these calls go through is documented in the HTTP API, including how to call it without the SDK.

The proxy is for reads. All submissions go through w.transactions. See Transactions & Fees.

Overview

Typescript SDK (dApp)

Python SDK

HTTP API

gRPC API

Reading Ledger State with the Walley Python SDK

Active contracts

Other named reads

Raw passthrough

​Active contracts

​Other named reads

​Raw passthrough

Active contracts

Other named reads

Raw passthrough