Reading from Intelligent Contracts

Public view methods read Intelligent Contract state without submitting a consensus transaction. They do not need a transaction fee or signing account.

Basic read

import { createClient } from 'genlayer-js';
import { localnet } from 'genlayer-js/chains';
import { TransactionHashVariant } from 'genlayer-js/types';
 
const client = createClient({ chain: localnet });
 
const result = await client.readContract({
  address: contractAddress,
  functionName: 'get_complete_storage',
  args: [],
  transactionHashVariant: TransactionHashVariant.LATEST_FINAL,
});

Choose the state snapshot

Variant	Use it for
`LATEST_FINAL`	Durable application state after finalization. This is the conservative default for accounting and irreversible UI decisions.
`LATEST_NONFINAL`	The newest available non-final state. Use it for responsive interfaces that can tolerate an appeal or recomputation changing the result.

Omit transactionHashVariant when the chain's default is appropriate. Be explicit when an application depends on finality semantics.

Arguments and return formats

const userInfo = await client.readContract({
  address: contractAddress,
  functionName: 'get_user_info',
  args: [userId],
  transactionHashVariant: TransactionHashVariant.LATEST_FINAL,
});

Use kwargs instead of args when the contract API is clearer with named arguments. The default result is decoded into GenLayer calldata values. Advanced consumers can request rawReturn: true for raw bytes or jsonSafeReturn: true where supported by the selected client surface.

Reads after a write

Waiting for a decision and reading the latest non-final state is faster, but that state can still move. Waiting for finalization and reading LATEST_FINAL gives a durable pair:

await client.waitForFinalization({ hash: txId });
 
const value = await client.readContract({
  address: contractAddress,
  functionName: 'get_storage',
  args: [],
  transactionHashVariant: TransactionHashVariant.LATEST_FINAL,
});

Error handling

try {
  const value = await client.readContract({
    address: contractAddress,
    functionName: 'get_data',
    args: [],
  });
  console.log(value);
} catch (error) {
  console.error('Contract read failed', error);
}

Do not classify errors only by matching an English message. Preserve the RPC error data so the application can decode a custom error with the deployment's matching ABI and the Error & Revert Reference.

Querying a Transaction Writing Data to Intelligent Contracts