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Use a function to turn EVM state or event inputs into a derived record. This example queries a token balance and carries the read context in its output.

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Chain and block context

Provide a chain supported by your node backend, a concrete block identifier, a token contract, and a holder address. Use a block that the backend can serve. EVM(chain_id, block_id) binds the object’s state reads and contract queries to that context.

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Prerequisites

  • A BlockX execution environment with EVM node access.
  • A contract that implements balanceOf(address)(uint256) at the selected block.
  • Function dependencies matching the BlockX checkout’s python/pyproject.toml.

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Write the function

Keep balance as an integer. To write the record to a table, prepare compatible target columns; table writers project returned records onto the target schema.

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Submit the arguments

For one-off computation, place [chain_id, block_id, token, holder] in one row of InputsCallConfig.callList and use ReturnValueHandler. See Run once for the submission pattern. For trigger-table computation, build these arguments from the source schema. Pass the row’s block context when processing history; selecting a bundle does not bind every row’s dependency reads to one historical block.

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Confirm the result

Check task success and inspect balance, block_id, and token in the returned record. A returned value confirms the computation for those arguments; it does not write a table unless you select a table Writer Plugin.

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Handle failures

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