evmEventDecoder

See the Handling contract events guide for usage examples and event specification routes.

Returns a query-transformer combo that instructs the source to fetch and decode smart contract event logs.

evmEventDecoder<T>(config: DecodedEventPipeArgs<T>): Transformer

Parameters:

range: Block range { from: number | 'latest', to?: number } (required)
contracts: Array of contract addresses or a contractFactory (optional; omit to receive events from all contracts)
events: Map of event names to ABI event objects or { event, params } filter objects (required)
profiler: Profiler config shard for labeling the transformer in profiling data { name: string } (optional)
onError: Error handler (optional)

A log goes to one entry of events only. If two entries can match the same log, the decoder fails at start with E0004 instead of silently dropping the log for one of them. Entries of one event are fine when their filters share no value ({ from: ALICE } and { from: BOB }), or when the topic count differs, as with ERC-20 and ERC-721 Transfer. To get overlapping filters, put each in its own evmEventDecoder(): every output then receives all the logs its filter matches. A decoder emits only the logs its own entries ask for, not logs that another output requested. Example:

import { commonAbis, evmEventDecoder, evmPortalStream } from "@subsquid/pipes/evm";

const decoder = evmEventDecoder({
  range: { from: 20000000, to: 20100000 },
  contracts: ["0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48"],
  events: {
    transfer: commonAbis.erc20.events.Transfer,
  },
});

const stream = evmPortalStream({
  id: "usdc-transfers",
  portal: "https://portal.sqd.dev/datasets/ethereum-mainnet",
  outputs: decoder,
});

for await (const { data } of stream) {
  console.log(`decoded ${data.transfer.length} transfers`);
}

Decoded event structure

Each entry in the output arrays is a DecodedEvent object:

Field	Type	Description
`event`	decoded event type	Decoded event data fields
`contract`	`string`	Address of the contract that emitted the event
`block`	`{ number: number, hash: string }`	Block number and hash
`timestamp`	`Date`	Block timestamp
`rawEvent`	`Log`	Raw log with `address`, `topics`, `data`, `transactionHash`, `logIndex`, `transactionIndex`
`factory`	`{ contract, blockNumber, event }`	Present only when using a factory; carries the factory deployment event that discovered this contract

commonAbis

import { commonAbis } from '@subsquid/pipes/evm'

commonAbis is a built-in collection of typed ABI modules. See the Handling contract events guide for usage examples.

commonAbis.erc20

Events:

	Signature
`commonAbis.erc20.events.Transfer`	`Transfer(address indexed from, address indexed to, uint256 value)`
`commonAbis.erc20.events.Approval`	`Approval(address indexed owner, address indexed spender, uint256 value)`

Functions:

	Signature
`commonAbis.erc20.functions.name`	`name() → string`
`commonAbis.erc20.functions.symbol`	`symbol() → string`
`commonAbis.erc20.functions.decimals`	`decimals() → uint8`
`commonAbis.erc20.functions.totalSupply`	`totalSupply() → uint256`
`commonAbis.erc20.functions.balanceOf`	`balanceOf(address _owner) → uint256`
`commonAbis.erc20.functions.allowance`	`allowance(address _owner, address _spender) → uint256`
`commonAbis.erc20.functions.transfer`	`transfer(address _to, uint256 _value) → bool`
`commonAbis.erc20.functions.approve`	`approve(address _spender, uint256 _value) → bool`
`commonAbis.erc20.functions.transferFrom`	`transferFrom(address _from, address _to, uint256 _value) → bool`

Overview

Pipes SDK

Squid SDK

Alternative clients

evmEventDecoder