> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sqd.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Block data for EVM

> Block data interfaces for EVM indexing — type definitions for blocks, transactions, logs, traces, and state diffs.

`EvmBatchProcessor` follows the common [squid processor architecture](/en/sdk/squid-sdk/overview), in which data processing happens within the [batch handler](/en/sdk/squid-sdk/reference/processors/architecture#processorrun), a function repeatedly called on batches of on-chain data. The function takes a single argument called "batch context". Its structure follows the [common batch context layout](/en/sdk/squid-sdk/reference/processors/architecture#batch-context), with `ctx.blocks` being an array of `BlockData` objects containing the data to be processed, aligned at the block level.

For `EvmBatchProcessor` the `BlockData` interface is defined as follows:

```ts theme={"system"}
export type BlockData<F extends FieldSelection = {}> = {
  header: BlockHeader<F>
  transactions: Transaction<F>[]
  logs: Log<F>[]
  traces: Trace<F>[]
  stateDiffs: StateDiff<F>[]
}
```

`F` here is the type of the argument of the [`setFields()`](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection) processor method.

`BlockData.header` contains the block header data. The rest of the fields are iterables containing four kinds of blockchain data. The canonical ordering within each iterable depends on the data kind:

* `transactions` and `logs` are ordered in the same way as they are within blocks;
* [`stateDiffs`](/en/sdk/squid-sdk/reference/processors/evm-batch/state-diffs) follow the order of transactions that gave rise to them;
* `traces` are ordered in a deterministic but otherwise unspecified way.

The exact fields available in each data item type are inferred from the `setFields()` call argument. They are documented on the [field selection](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection) page:

* [transactions section](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection#transactions);
* [logs section](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection#logs);
* [traces section](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection#traces);
* [state diffs section](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection#state-diffs);
* [block header section](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection#block-headers).

## Example

The handler below simply outputs all the log items emitted by the contract `0x2E645469f354BB4F5c8a05B3b30A929361cf77eC` in [real time](/en/sdk/squid-sdk/resources/unfinalized-blocks):

```ts theme={"system"}
import { TypeormDatabase } from '@subsquid/typeorm-store'
import { EvmBatchProcessor } from '@subsquid/evm-processor'

const CONTRACT_ADDRESS = '0x2E645469f354BB4F5c8a05B3b30A929361cf77eC'.toLowerCase()

const processor = new EvmBatchProcessor()
  .setGateway('https://v2.archive.subsquid.io/network/ethereum-mainnet')
  .setRpcEndpoint('<my_eth_rpc_url>')
  .setFinalityConfirmation(75)
  .setBlockRange({ from: 17000000 })
  .addLog({
    address: [CONTRACT_ADDRESS]
  })
  .setFields({ // could be omitted: this call does not change the defaults
    log: {
      topics: true,
      data: true
    }
  })

processor.run(new TypeormDatabase(), async (ctx) => {
  for (let c of ctx.blocks) {
    for (let log of c.logs) {
      if (log.address === CONTRACT_ADDRESS) {
        ctx.log.info(log, `Log:`)
      }
    }
  }
})
```

One can experiment with the [`setFields()`](/en/sdk/squid-sdk/reference/processors/evm-batch/field-selection) argument and see how the output changes.

For more elaborate examples, check [EVM Examples](/en/sdk/squid-sdk/examples).