ContractCodeUpdated

Event v334 → current #5

Emitted when a contract's code is updated to a different code hash.

View events on chain

Useful for: developersanalytics

The Big Picture

A privileged upgrade mechanism that swaps contract code in-place, preserving address and storage.

Use Cases

Track contract upgrades
Monitor governance-approved changes
Build upgrade history

From Chain Metadata

A contract's code was updated.

Triggers

Emitted by

set_code

Preconditions

Contract exists
Caller has root privileges
New code exists

Effects

Storage Modified

CodeInfoOf ContractInfoOf

Postconditions

Contract references new code_hash

Side Effects

Contract behavior changes immediately

Event Data

#	Name	Type	Description
0	contract	AccountId	Contract whose code was upgraded (hex -> SS58)
1	new_code_hash	H256 T::Hash	Hash of the new code now running
2	old_code_hash	H256 T::Hash	Hash of the previous code (before upgrade)

Code Examples

import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443

const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);

// Subscribe to ContractCodeUpdated events
client.finalizedBlock$.subscribe(async (block) => {
  const events = await api.event.Contracts.ContractCodeUpdated.get(block.hash);
  for (const evt of events) {
    console.log("ContractCodeUpdated:", evt.payload);
  }
});

Runtime Info

Pallet Index: 29
Event Index: 5
First Version: v334
Current Version: v411

Back to Contracts Events