Decoding getProgramAccounts results with Codama decoders: request base64 encoding and feed decodeAccount, not jsonParsed

Problem: you have a Codama-generated client (Solana Kit) and want every account of one struct type from your program. getProgramAccounts with a memcmp filter on the account discriminator returns results, but passing them into the generated decodeOffer({ address, data, ... }) fails.

Two things are going on: 1. Codama-generated clients (as of 2025) do not generate a "fetch all accounts of type X" helper. Only single/multiple-by-address fetchers exist, so the getProgramAccounts + decode step is yours to write. 2. The decoder wants raw bytes. If you call getProgramAccounts with encoding: "jsonParsed", account.data comes back as a [base64String, "base64"] tuple, which is not what the decoder accepts. Request encoding: "base64" and convert the returned base64 string to a Uint8Array before handing it to the decoder.

Working shape:

const results = await rpc.getProgramAccounts(PROGRAM_ADDRESS, {
  encoding: "base64",
  filters: [{ memcmp: { offset: 0n, bytes: bs58.encode(Buffer.from(OFFER_DISCRIMINATOR)) } }],
}).send();
// then build an EncodedAccount { address, data: bytes, executable, lamports, programAddress, space }
// and run decodeAccount(encodedAccount, getOfferDecoder())

The memcmp filter's bytes must be base58-encoded, even when the account data itself is requested as base64 — mixing those two encodings up is the other common failure.

If you would rather not hand-roll it, the solana-kite package wraps this as connection.getAccountsFactory(PROGRAM_ADDRESS, OFFER_DISCRIMINATOR, getOfferDecoder()), returning fully decoded accounts. Swap the discriminator/decoder pair for any other generated struct.

Source: adapted from a Stack Exchange answer by mikemaccana (question by mikemaccana), https://solana.stackexchange.com/questions/21861/how-can-i-fetch-and-decode-my-accounts-using-codama-and-solana-kit — CC BY-SA 4.0