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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.
from stellar_sdk import xdr, Address

def get_ledger_key_contract_code(contract_id: str) -> str:
ledger_key = xdr.LedgerKey(
type=xdr.LedgerEntryType.CONTRACT_DATA,
contract_data=xdr.LedgerKeyContractData(
contract=Address(contract_id).to_xdr_sc_address(),
key=xdr.SCVal(xdr.SCValType.SCV_LEDGER_KEY_CONTRACT_INSTANCE),
durability=xdr.ContractDataDurability.PERSISTENT
)
)
return ledger_key.to_xdr()

print(
get_ledger_key_contract_code(
"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.

from stellar_sdk import xdr

def get_ledger_key_wasm_id(contract_code_ledger_entry_data: str) -> str:
# First, we dig the wasm_id hash out of the xdr we received from RPC
contract_code_wasm_hash = xdr.LedgerEntryData.from_xdr(
contract_code_ledger_entry_data
).contract_data.val.instance.executable.wasm_hash
# Now, we can create the `LedgerKey` as we've done in previous examples
ledger_key = xdr.LedgerKey(
type=xdr.LedgerEntryType.CONTRACT_CODE,
contract_code=xdr.LedgerKeyContractCode(
hash=contract_code_wasm_hash
),
)
return ledger_key.to_xdr()

print(
get_ledger_key_wasm_id(
"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 Lab.

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