def Query(self):
"""
Query the smart contract for its token information (name, symbol, decimals).
Args:
wallet (neo.Wallets.Wallet): a wallet instance.
Returns:
None: if the NEP5Token instance `Name` is already set.
True: if all information was retrieved.
False: if information retrieval failed.
"""
if self.name is not None:
# don't query twice
return
sb = ScriptBuilder()
sb.EmitAppCallWithOperation(self.ScriptHash, 'name')
sb.EmitAppCallWithOperation(self.ScriptHash, 'symbol')
sb.EmitAppCallWithOperation(self.ScriptHash, 'decimals')
engine = ApplicationEngine.Run(sb.ToArray())
results = engine.EvaluationStack.Items
try:
self.name = results[0].GetString()
self.symbol = results[1].GetString()
self.decimals = results[2].GetBigInteger()
if len(self.name) > 1 and self.name != 'Stack Item' \
and len(self.symbol) > 1 and self.symbol != 'Stack Item'\
and self.decimals < 10:
return True
except Exception as e:
logger.info("could not query token %s " % e)
return False
def Query(self, wallet):
"""
Query the smart contract for its token information (name, symbol, decimals).
Args:
wallet (neo.Wallets.Wallet): a wallet instance.
Returns:
None: if the NEP5Token instance `Name` is already set.
True: if all information was retrieved.
False: if information retrieval failed.
"""
if self.name is not None:
# don't query twice
return
sb = ScriptBuilder()
sb.EmitAppCallWithOperation(self.ScriptHash, 'name')
sb.EmitAppCallWithOperation(self.ScriptHash, 'symbol')
sb.EmitAppCallWithOperation(self.ScriptHash, 'decimals')
tx, fee, results, num_ops = test_invoke(sb.ToArray(), wallet, [])
try:
self.name = results[0].GetString()
self.symbol = results[1].GetString()
self.decimals = results[2].GetBigInteger()
return True
except Exception as e:
logger.error("could not query token %s " % e)
return False
def Query(self):
"""
Query the smart contract for its token information (name, symbol, decimals).
Args:
wallet (neo.Wallets.Wallet): a wallet instance.
Returns:
None: if the NEP5Token instance `Name` is already set.
True: if all information was retrieved.
False: if information retrieval failed.
"""
if self.name is not None:
# don't query twice
return
sb = ScriptBuilder()
sb.EmitAppCallWithOperation(self.ScriptHash, 'name')
sb.EmitAppCallWithOperation(self.ScriptHash, 'symbol')
sb.EmitAppCallWithOperation(self.ScriptHash, 'decimals')
snapshot = GetBlockchain().Default()._db.createSnapshot().Clone()
engine = None
try:
engine = ApplicationEngine.Run(snapshot,
sb.ToArray(),
exit_on_error=True,
gas=Fixed8.FromDecimal(10.0),
test_mode=False)
except Exception as e:
traceback.print_exc()
pass
if engine and len(engine.ResultStack.Items) == 3:
results = engine.ResultStack.Items
try:
self.name = results[0].GetString()
self.symbol = results[1].GetString()
self.decimals = results[2].GetBigInteger()
if len(self.name) > 1 and self.name != 'Stack Item' \
and len(self.symbol) > 1 and self.symbol != 'Stack Item' \
and self.decimals < 10:
return True
except Exception as e:
pass
return False
def example2():
source_address = "AJQ6FoaSXDFzA6wLnyZ1nFN7SGSN2oNTc3"
source_script_hash = address_to_scripthash(source_address)
# start by creating a base InvocationTransaction
# the inputs, outputs and Type do not have to be set anymore.
invocation_tx = InvocationTransaction()
# Since we are building a raw transaction, we will add the raw_tx flag
invocation_tx.raw_tx = True
# often times smart contract developers use the function ``CheckWitness`` to determine if the transaction is signed by somebody eligible of calling a certain method
# in order to pass that check you want to add the corresponding script_hash as a transaction attribute (this is generally the script_hash of the public key you use for signing)
# Note that for public functions like the NEP-5 'getBalance' and alike this would not be needed, but it doesn't hurt either
invocation_tx.Attributes.append(
TransactionAttribute(usage=TransactionAttributeUsage.Script,
data=source_script_hash))
# next we need to build a 'script' that gets executed against the smart contract.
# this is basically the script that calls the entry point of the contract with the necessary parameters
smartcontract_scripthash = UInt160.ParseString(
"31730cc9a1844891a3bafd1aa929a4142860d8d3")
sb = ScriptBuilder()
# call the NEP-5 `name` method on the contract (assumes contract address is a NEP-5 token)
sb.EmitAppCallWithOperation(smartcontract_scripthash, 'name')
invocation_tx.Script = binascii.unhexlify(sb.ToArray())
# at this point we've build our unsigned transaction and it's time to sign it before we get the raw output that we can send to the network via RPC
# we need to create a Wallet instance for helping us with signing
wallet = UserWallet.Create('path',
to_aes_key('mypassword'),
generate_default_key=False)
# if you have a WIF use the following
# this WIF comes from the `neo-test1-w.wallet` fixture wallet
private_key = KeyPair.PrivateKeyFromWIF(
"Ky94Rq8rb1z8UzTthYmy1ApbZa9xsKTvQCiuGUZJZbaDJZdkvLRV")
# if you have a NEP2 encrypted key use the following instead
# private_key = KeyPair.PrivateKeyFromNEP2("NEP2 key string", "password string")
# we add the key to our wallet
wallet.CreateKey(private_key)
# and now we're ready to sign
context = ContractParametersContext(invocation_tx)
wallet.Sign(context)
invocation_tx.scripts = context.GetScripts()
raw_tx = invocation_tx.ToArray()
return raw_tx
