Indexer Transactions

Transaction and Block Data

There is no onTransaction handler. Transaction and block data reach a handler through event.transaction and event.block.

They carry only the fields the handler asks for. List them in fields:

indexer.onEvent(
  {
    contract: "MyContract",
    event: "Transfer",
    fields: { transaction: ["hash", "from"], block: ["timestamp"] },
  },
  async ({ event, context }) => {
    event.transaction.hash; // string
    event.block.timestamp; // number
    event.transaction.gasUsed; // Type error: not listed in fields
  },
);

Reading a field you didn't list is a type error. event.block.number is available without listing it.

Available on indexer.onEvent and indexer.contractRegister. Two handlers on the same event can list different fields.

Write the list inline, as above. To reuse one, declare it as const:

const txFields = { transaction: ["hash", "from"] } as const;

indexer.onEvent({ contract: "MyContract", event: "Transfer", fields: txFields }, handler);

Selecting in config.yaml instead

field_selection applies to every handler of an event, or of every event when placed at the root level. Prefer fields in the handler — the list sits next to the code that reads it. A handler's fields overrides field_selection.

field_selection:
  transaction_fields: [hash, from]
  block_fields: [timestamp]

Available Transaction Fields

transactionIndex, hash, from, to, gas, gasPrice, maxPriorityFeePerGas, maxFeePerGas, cumulativeGasUsed, effectiveGasPrice, gasUsed, input, nonce, value, v, r, s, contractAddress, logsBloom, root, status, yParity, accessList, maxFeePerBlobGas, blobVersionedHashes, type, l1Fee, l1GasPrice, l1GasUsed, l1FeeScalar, gasUsedForL1, authorizationList

Some are chain-specific and read as undefined where they don't apply: the l1* fields need an L2, root only appears on pre-Byzantium transactions.

Available Block Fields

event.block.number is always available. The rest must be listed:

timestamp, hash, parentHash, nonce, sha3Uncles, logsBloom, transactionsRoot, stateRoot, receiptsRoot, miner, difficulty, totalDifficulty, extraData, size, gasLimit, gasUsed, uncles, baseFeePerGas, blobGasUsed, excessBlobGas, parentBeaconBlockRoot, withdrawalsRoot, l1BlockNumber, sendCount, sendRoot, mixHash

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