ContractEmitted

Event v334 → current #3

Emitted when a contract emits a custom event during execution.

Useful for: developersanalytics

The Big Picture

Contracts can emit their own events. This wraps those custom events. The data field contains contract-defined data that must be decoded using the contract's ABI.

Use Cases

Monitor contract-specific events
Build contract-aware indexers
Debug contract execution

From Chain Metadata

A custom event emitted by the contract.

Triggers

Emitted by

call call_old_weight

Preconditions

Contract is executing
Contract calls seal_deposit_event

Effects

Storage Modified

ContractInfoOf

Postconditions

Custom event data recorded

Side Effects

Gas consumed for event emission

Event Data

#	Name	Type	Description
0	contract	AccountId	Contract that emitted this custom event (hex -> SS58)
1	data	Vec<u8> Vec	Contract-defined event data (decode with contract ABI)

Code Examples

import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";

const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });

// Subscribe to ContractEmitted events
api.query.system.events((events) => {
  events
    .filter(({ event }) =>
      event.section === stringCamelCase("Contracts") &&
      event.method === "ContractEmitted"
    )
    .forEach(({ event }) => {
      console.log("ContractEmitted:", event.data.toHuman());
    });
});

Runtime Info

Pallet Index: 29
Event Index: 3
First Version: v334
Current Version: v393

Back to Contracts Events