watchContractEvent

Watches and returns emitted contract event logs.

This Action will batch up all the event logs found within the pollingInterval, and invoke them via onLogs.

watchContractEvent will attempt to create an Event Filter and listen to changes to the Filter per polling interval, however, if the RPC Provider does not support Filters (ie. eth_newFilter), then watchContractEvent will fall back to using getLogs instead.

Usage

example.tsclient.ts

import { publicClient } from './client'
import { wagmiAbi } from './abi'

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  onLogs: logs => console.log(logs)
})
// > [{ ... }, { ... }, { ... }]
// > [{ ... }, { ... }]
// > [{ ... }, { ... }, { ... }, { ... }]

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

Scoping to an Event Name

You can scope to an event on the given ABI.

example.tsabi.tsclient.ts

import { publicClient } from './client'
import { wagmiAbi } from './abi'

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  eventName: 'Transfer',
  onLogs: logs => console.log(logs)
})
// > [{ ... }, { ... }, { ... }]
// > [{ ... }, { ... }]
// > [{ ... }, { ... }, { ... }, { ... }]

export const wagmiAbi = [
  ...
  {
    inputs: [
      {
        indexed: true,
        name: "from",
        type: "address",
      },
      { indexed: true, name: "to", type: "address" },
      {
        indexed: true,
        name: "tokenId",
        type: "uint256",
      },
    ],
    name: "Transfer",
    type: "event",
  },
  ...
] as const;

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

Scoping to Event Arguments

You can scope to given indexed event arguments.

In the example below, we want to filter out Transfers that were sent by the address "0xc961145a54C96E3aE9bAA048c4F4D6b04C13916b".

Only indexed arguments on the event ABI are candidates for args (see abi.ts).

example.tsabi.tsclient.ts

import { publicClient } from './client'
import { wagmiAbi } from './abi'

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  eventName: 'Transfer',
  args: { from: '0xc961145a54C96E3aE9bAA048c4F4D6b04C13916b' },
  onLogs: logs => console.log(logs)
})
// > [{ ... }, { ... }, { ... }]
// > [{ ... }, { ... }]
// > [{ ... }, { ... }, { ... }, { ... }]

export const wagmiAbi = [
  ...
  {
    inputs: [
      {
        indexed: true,
        name: "from",
        type: "address",
      },
      { 
        indexed: true, 
        name: "to", 
        type: "address" 
      },
      {
        indexed: false,
        name: "tokenId",
        type: "uint256",
      },
    ],
    name: "Transfer",
    type: "event",
  },
  ...
] as const;

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

Returns

UnwatchFn

A function that can be invoked to stop watching for new event logs.

Arguments

abi

Type: Abi

The contract's ABI.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi, 
  onLogs: logs => console.log(logs)
})

onLogs

Type: (Log[]) => void

The new event logs.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  onLogs: logs => console.log(logs) 
})

address (optional)

Type: Address

The contract address. If no address is provided, then it will emit all events matching the event signatures on the ABI.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2', 
  abi: wagmiAbi,
  onLogs: logs => console.log(logs)
})

args (optional)

Type: Inferred from ABI.

Event arguments to filter logs.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  eventName: 'Transfer', 
  args: ['0xc961145a54C96E3aE9bAA048c4F4D6b04C13916b'], 
  onLogs: logs => console.log(logs)
})

eventName (optional)

Type: string

An event name to filter logs.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  eventName: 'Transfer', 
  onLogs: logs => console.log(logs)
})

batch (optional)

Type: boolean
Default: true

Whether or not to batch logs between polling intervals.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  batch: false, 
  onLogs: logs => console.log(logs)
})

onError (optional)

Type: (error: Error) => void

Error thrown from listening for new event logs.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  onError: error => console.log(error), 
  onLogs: logs => console.log(logs)
})

pollingInterval (optional)

Type: number

Polling frequency (in ms). Defaults to the Client's pollingInterval config.

const unwatch = publicClient.watchContractEvent({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  pollingInterval: 1_000, 
  onLogs: logs => console.log(logs)
})

watchContractEvent ​

Usage ​

Scoping to an Event Name ​

Scoping to Event Arguments ​

Returns ​

Arguments ​

abi ​

onLogs ​

address (optional) ​

args (optional) ​

eventName (optional) ​

batch (optional) ​

onError (optional) ​

pollingInterval (optional) ​