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Retrieve a contract code ledger entry using the Python SDK

When you deploy a contract, first the code is "installed" (i.e., it is uploaded onto the blockchain). This creates a LedgerEntry containing the Wasm byte-code, which is uniquely identified by its hash (that is, the hash of the uploaded code itself). Then, when the contract is "deployed," we create a LedgerEntry with a reference to that code's hash. So fetching the contract code is a two-step process:

  1. First, we look up the contract itself, to see which code hash it is referencing.
  2. Then, we can look up the raw Wasm byte-code using that hash.
import { Contract } from "@stellar/stellar-sdk";

function getLedgerKeyContractCode(contractId) {
const instance = new Contract(contractId).getFootprint();
return instance.toXDR("base64");
}

console.log(
getLedgerKeyContractCode(
"CCPYZFKEAXHHS5VVW5J45TOU7S2EODJ7TZNJIA5LKDVL3PESCES6FNCI",
),
);
// OUTPUT: AAAABgAAAAGfjJVEBc55drW3U87N1Py0Rw0/nlqUA6tQ6r28khEl4gAAABQAAAAB

We then take our output from this function, and use it as the element in the keys array parameter in our call to the getLedgerEntries method.

{
"jsonrpc": "2.0",
"id": 8675309,
"method": "getLedgerEntries",
"params": {
"keys": ["AAAABgAAAAGfjJVEBc55drW3U87N1Py0Rw0/nlqUA6tQ6r28khEl4gAAABQAAAAB"]
}
}

And the response we get contains the LedgerEntryData that can be used to find the hash we must use to request the Wasm byte-code. This hash is the LedgerKey that's been associated with the deployed contract code.

{
"jsonrpc": "2.0",
"id": 8675309,
"result": {
"entries": [
{
"key": "AAAABgAAAAGfjJVEBc55drW3U87N1Py0Rw0/nlqUA6tQ6r28khEl4gAAABQAAAAB",
"xdr": "AAAABgAAAAAAAAABn4yVRAXOeXa1t1POzdT8tEcNP55alAOrUOq9vJIRJeIAAAAUAAAAAQAAABMAAAAA5DNtbckOGVRsNVb8L7X/lIhAOy2o5G6GkLKXvc7W8foAAAAA",
"lastModifiedLedgerSeq": 261603
}
],
"latestLedger": 262322
}
}

Now take the xdr field from the previous response's result object, and create a LedgerKey from the hash contained inside.

import { xdr } from "@stellar/stellar-sdk";

function getLedgerKeyWasmId(contractCodeLedgerEntryData) {
const entry = xdr.LedgerEntryData.fromXDR(
contractCodeLedgerEntryData,
"base64",
);

const wasmHash = entry
.contractData()
.val()
.instance()
.executable()
.wasmHash();

let ledgerKey = xdr.LedgerKey.contractCode(
new xdr.LedgerKeyContractCode({
hash: wasmHash,
}),
);

return ledgerKey.toXDR("base64");
}

console.log(
getLedgerKeyWasmId(
"AAAABgAAAAAAAAABn4yVRAXOeXa1t1POzdT8tEcNP55alAOrUOq9vJIRJeIAAAAUAAAAAQAAABMAAAAA5DNtbckOGVRsNVb8L7X/lIhAOy2o5G6GkLKXvc7W8foAAAAA",
),
);
// OUTPUT: AAAAB+QzbW3JDhlUbDVW/C+1/5SIQDstqORuhpCyl73O1vH6

Now, finally we have a LedgerKey that correspond to the Wasm byte-code that has been deployed under the ContractId we started out with so very long ago. This LedgerKey can be used in a final request to the Soroban-RPC endpoint.

{
"jsonrpc": "2.0",
"id": 8675309,
"method": "getLedgerEntries",
"params": {
"keys": ["AAAAB+QzbW3JDhlUbDVW/C+1/5SIQDstqORuhpCyl73O1vH6"]
}
}

And the response we get contains (even more) LedgerEntryData that we can decode and parse to get the actual, deployed, real-life contract byte-code. We'll leave that exercise up to you. You can check out what is contained using the "View XDR" page of the Stellar Laboratory.

{
"jsonrpc": "2.0",
"id": 8675309,
"result": {
"entries": [
{
"key": "AAAAB+QzbW3JDhlUbDVW/C+1/5SIQDstqORuhpCyl73O1vH6",
"xdr": "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",
"lastModifiedLedgerSeq": 368441,
"liveUntilLedgerSeq": 2442040
}
],
"latestLedger": 370940
}
}