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Fetch the complete documentation index at: https://docs.sqd.dev/llms.txt

Use this file to discover all available pages before exploring further.

In Solana Squid SDK, the data is processed by repeatedly calling the user-defined batch handler function on batches of on-chain data. The sole argument of the batch handler is its context ctx, and ctx.blocks is an array of Block objects containing the data to be processed, aligned at the block level. For SolanaBatchProcessor the Block interface is defined as follows: 
export interface Block<F extends FieldSelection = {}> {
  header: BlockHeader<F>;
  instructions: Instruction<F>[];
  transactions: Transaction<F>[];
  logs: LogMessage<F>[];
  balances: Balance<F>[];
  tokenBalances: TokenBalance<F>[];
  rewards: Reward<F>[];
}
F here is the type of the argument of the setFields() processor method. BlockData.header contains the block header data. The rest of the fields are iterables containing the six kinds of blockchain data. Canonical ordering within each iterable depends on the data kind:
  • transactions are ordered in the same way as they are within blocks;
  • instructions follow the order of transactions that gave rise to them;
  • tokenBalances 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 page:

​
Example

The handler below simply outputs all the log items emitted by the contract 0x2E645469f354BB4F5c8a05B3b30A929361cf77eC in real time: 
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() argument and see how the output changes. For more elaborate examples, check Solana Examples. —>