Questions tagged [python]
Python is a dynamic and strongly typed programming language designed to emphasize usability.
218
questions
0
votes
0answers
11 views
Real time access of transaction using websockets and web3py
I want to build the backend in Django using django channels that access the realtime blockchain data.
Here is my smart contract.
mapping(uint => Task) public tasks;
event TaskCreated(
uint ...
0
votes
2answers
28 views
Call an existing python code inside a solidity smart contract
I want to call some existing code (written in Python) inside my Ethereum smart contract (written in solidity). Is it possible to do that? if so, how can we do it?
1
vote
0answers
29 views
Require not working on geth private node
I have created this contract to manage a votation:
pragma solidity ^0.5.7;
contract Votacion{
mapping(uint => address[]) private votosCandidatos;
uint[] listaCandidatos;
bool abierta;
address ...
1
vote
0answers
19 views
Recover public key from message and signature [duplicate]
I try to recover a public key (not an address) from a message and a signature.
I have the following message:
def offer_hash(msg, nonce):
types = ['bytes',
'bytes',
'...
0
votes
0answers
26 views
Why does this code outputs error:“unknown account”?
Python code:
from web3 import Web3
import json
web = "http://10.0.141.114:8545"
web3 = Web3(Web3.HTTPProvider(web))
abi=json.loads('[ { "constant": false, "inputs": [ { "name": "_cad_number", "type":...
1
vote
0answers
28 views
Web3.py transfer call failing, not sure why
I am trying to learn how to work with ethereum and ERC20 tokens. I have managed to setup ganache and deploy my contract. I can see it on ganache and I can connect and read the balance of the token on ...
1
vote
1answer
50 views
How get private key in private network?
I launched a private RPC Blockchain network and connected through another computer to this network. The connection is successful. How can I get a private key(through Python) if the file is on another ...
2
votes
1answer
48 views
Error trying to get events in web3.py via Infura
I was trying to get all events from my smart contract (in Ropsten) via Infura node.
The problem is that I know that Infura does no support creating filters, but I don't know how to get events by ...
1
vote
0answers
26 views
how can I get the account locked information via python web3?
There is a command personal.listWallets in geth cli to get the account locked/unlocked status such as below:
> personal.listWallets[1]
{
accounts: [{
address: "...
1
vote
0answers
23 views
pass struct from web3 python interface to solidity
I have created a smart contract with some solidity functions which take structs, enums and mappings(all defined in my contract) as arguments. I intend to call these functions from my web3 python ...
1
vote
1answer
60 views
Call Smart Contract Function in Python Script
My situation is reverse to most. I am relatively experienced in coding in Solidity, but have absolutely no experience in using Python.
What I would ideally like to do is have a script that will, in ...
1
vote
1answer
53 views
Problems calling function with web3 from python
I was trying to call a function from my python server to a contract deployed in Ropsten.
This is my method in the contract:
function send(address receiver, uint amount) public {
require(msg....
0
votes
1answer
33 views
Error sending ether to a a smart contract deployed in ropsten with web3 with python
I am trying to send ether to a smart contract deployed on ropsten via infura, but I am having some problems in txn.
The error is "Error in Txn: Reverted".
The sender account has enought ether to ...
1
vote
1answer
39 views
web3py - Function Call when Sender Must Be Certain Address
I have a contract on Ropsten, and when I do this is python, I get a result:
result = contract.functions.getLastUpdateTime(0).call()
So I know the ABI is there, the address, etc.
There's another ...
0
votes
0answers
32 views
How to deploy contract instance in blockchain with abi and contract address?
I am following this (python ethereum interface tutorial) and contracts to compile and deploy in ganache cli.
Till now i am able to compile and deploy contracts with web3.py,py-solc and ganache node. ...
0
votes
1answer
33 views
DDEX Api Question for Python… Signing ETH Transactions?
Having an issue with signing a message for the DDEX api... I'm trying to do it in python, and for some reason my signature is off by two characters. Here's my code using the private key and UTC ...
1
vote
0answers
18 views
Inconsistent responses with 'eth_getTransactionByHash' through RPC API. Can anyone help?
I have been using the requests library with python to query the geth/rpc api in order to get ETH transaction data. I connected to geth via "geth --rpc --unlock TESTINGADDRESSWITHNOVALUE --allow-...
0
votes
0answers
34 views
Sign Message using passphrase only
I'm creating an authentication system using python and web3.py.
I'm trying to authenticate a user using
from web3.auto import w3
msg = 'sdb41554xcb4xc548cxd84dxcb'
message = encode_defunct(text=...
1
vote
0answers
14 views
fail for read ethereum node base on leveldb.py
I installed leveldb base on python3.6.but when I using leveldb.LevelDB import path for files to be read.
a error occered
"leveldb.LevelDBError: Corruption: 3 missing files; e.g.: D:/downloads_by_geth/...
0
votes
0answers
21 views
Can't install `eth-tester` Python Package
I am trying to install [eth-tester][1] Python Package so that I can use it to load test ethereum in my account by using its get_balance() function.
First when i installed this package using;
pip ...
2
votes
1answer
369 views
Convert BIP-39 mnemonic to Ethereum private key in Python
How do I convert a BIP-39 mnemonic to an Ethereum private key in Python (via BIP-44 key derivation)? All the libraries I found that gave me the intended result depend on the two1 package, which ...
0
votes
0answers
28 views
compile_files gives errror for given path of the contract [duplicate]
pragma solidity ^0.5.1;
import "./Owned.sol";
contract Greeter is Owned {
bytes32 public greeting;
event GreetingChange (
address indexed changer,
bytes32 indexed _from,
...
0
votes
0answers
56 views
how to write smart contract in django python?
I am trying to create a daap website in django. In django use apps to write views and urls to mvc pattern. I tried to create an app and wrote smartcontract there but i am not able to access it. I have ...
0
votes
1answer
93 views
Getting Error:VM Exception while processing transaction: revert', 'code': -32000. when deploying to Ganache using Web3.py
I get the following error message:
Getting Error:VM Exception while processing transaction: revert', 'code': -32000
I am connected to Ganache. Here is my code:
import json
from web3 import Web3
...
2
votes
1answer
87 views
solcx compile_files Key error
I am using python package py-solc-x for compiling the smart contract.
os.path.abspath("D:/new.sol")
Gives path where my test contract exits. 'D:\\new.sol'
Then i use compile_files to compile the ...
1
vote
1answer
103 views
How to access Parity node's mempool with web3.py?
I'm running a Parity node with parity --jsonrpc-api all, then connecting to it in python3 with w3 = web3.Web3(web3.HTTPProvider('http://localhost:8545')).
I can call print(w3.eth.getBlock('latest'))...
1
vote
1answer
123 views
How to build a simple transaction?
Where is the information on the tx package build protocol? Bitcoin as an example, Bitcoin Wiki - Protocol Documentation: tx
Is there an example of serialization for python like this answer to How to ...
0
votes
1answer
133 views
How to listen contract event in Python
The test contract is
pragma solidity ^0.5.0;
contract Test{
event Here(uint256 indexed a);
uint256 public a;
function add() public returns (uint256){
a += 1;
emit Here(...
0
votes
0answers
143 views
Web3py AttributeError: 'HTTPProvider' object has no attribute 'manager'
I am trying to use web3 in a Django based web application in a task which is run using celery and kafka. However while trying to use web3.eth module, I am getting the following error :
/...
2
votes
1answer
239 views
How pass a struct as an argument in call from python code
How call this contract functions from python code?
pragma solidity ^0.4.24;
pragma experimental ABIEncoderV2;
contract MY_PERSONS {
struct Person{
string name;
uint age;
}
...
0
votes
0answers
72 views
How to make ECDSA signature of (value_1, value_2) with web3 on Python?
I want to call function with four parameters. I know how to create two of them, but the last two is the r and s components of ECDSA signature of (param_1, param_2).
I tried this (and a lot of ...
0
votes
1answer
150 views
Is it possible to deploy a contract from python web3 if I have the ABI and bytecode from Remix?
Question says it all. I have a contract that I've written and compiled via Remix. I've dumped the ABI and Bytecode into local files, and I'm reading them into my python application. I'm following the ...
0
votes
0answers
47 views
call() returning BadFunctionCallOutput in web3.py
Have a very basic ERC721 contract based on OpenZeppelin-Solidity, as follows:
pragma solidity ^0.5.7;
import 'openzeppelin-solidity/contracts/token/ERC721/ERC721Mintable.sol';
import 'openzeppelin-...
1
vote
1answer
375 views
How to get the value of the transaction?
I am using web3.py but I need help to know the value of the transaction sent.
I know that the information is stored in the input but how do I parse the string. I know nothing about ABI.
Here is the ...
0
votes
2answers
137 views
No such file or directory: 'solc': 'solc'
I have been trying to follow the following tutorial
[https://github.com/adamyala/Your_First_Decentralized_Application_Python]
But the following error occurs:
I have followed all the steps in ...
1
vote
2answers
38 views
How can I read/write ethereum as a database by python code? [closed]
I am a startup in this domain. I see some article about Ethereum could save data as a contract. But they are too complex to me. If I already have an Ethereum account with some ETH. Is there some ...
2
votes
1answer
51 views
What's the difference between two params of web3.eth.filter?
I read official manual
What the difference between this
web3.eth.filter({'fromBlock': 'pending', 'toBlock': 'latest'})
and this?
web3.eth.filter('latest')
2
votes
0answers
132 views
How w3.eth.filter('latest').get_new_entries() works exactly?
I try to monitor new transactions.
from web3.auto import w3
import time
l = w3.eth.filter('latest')
while True:
ts = time.time()
ll = l.get_new_entries()
for i in ll:
print('===== Block ...
0
votes
1answer
83 views
Match web3py hashing function to solidity hashing function
If I am using web3py to hash some data, like so,
msgHash = w3.soliditySha3(['bytes32','bytes32'], [dataBytes, saltBytes]);
What would be the correct way to hash inside of a Solidity contract and ...
0
votes
1answer
802 views
Downloading a specific version of solc within a Docker image
I am working with the release of Solidity v0.4.25 for it works well with py-solc. When running on a local machine the codebase works quite well with 0.4.25. My issue currently is to get the codebase ...
2
votes
1answer
486 views
web3 python installation failes #include “Python.h” error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
I was trying to setup a new virtual environment for my project. I did not have any issues the last 5 Months installing web3, but today I just cant get it to work :(
pip install web3==4.1.0
...
1
vote
0answers
20 views
How to get live mempool transactions whitout full blokchain
I just want to analyse all mempool txs in realtime.
I cant use an api because after several requests my ip gets blocked for some minutes, so I dont get the txs in this time.
Thank you for help.
1
vote
1answer
215 views
Error whilst running solidity with python(py-solc)
I have been running my code which involves deployment of smart contract to Ethereum Ropsten network. I ran this successfully for some time but last week did installed another software after which ...
1
vote
0answers
453 views
How to fix a web3.py HTTPConnectionPool read timeout error
I have a web3.py program running and everything was seemingly working. I was connecting to my local server via the automatic connection offered in web3.py.
I am now getting the following error:
...
1
vote
0answers
199 views
Using web3.py, I get a key error when connecting to a remote server with 3 nodes running (autoconnect works fine)
I have a web3.py project that is successfully performing basic tasks (read from blockchain, send tx, process data, etc.). It is connected to a remote server that is running an ETH node, a Rinkeby node,...
1
vote
1answer
120 views
Hash functions soldity to python
In Solidity, I run the following code:
function hashTest() public returns(bytes32,bytes32,bytes32) {
bytes32 _solution = 0xbc756c25d68ea2f260ea5f15e1e1c734c019cbc014270dd386eacca4699f60f6;
bytes32 v ...
1
vote
1answer
85 views
Bit manipulation (python vs solidity)
I am working on translating code from Python to Solidity and everything has worked up until this last loop. Cannot figure out where the difference is in the code (besides the bytes being in decimal ...
0
votes
1answer
281 views
How to deploy contract with local private key?
I am trying to deploy my contract onto the blockchain in my private network with local private key (no wallet: I used web3.auto.w3.account.create()).
I know how to send normal transaction with local ...
0
votes
1answer
121 views
Problem with running web3.py code
I am trying to run this code
from web3 import Web3, HTTPProvider
import json
import pprint
import requests
from random import randint
# Debug flags
debug_transaction = False
debug_CALL_transactions ...
1
vote
1answer
38 views
What is the best (cheapest) method to store RGB/RGBA pixel data in a smart contract (on ethereum-classic blockchain) with python?
I would to implement a method to store pixel (RGB/RGBA) in a Smart contract (on ethereum-classic blockchain) from python and with the cheapest method ( when storing and updating pixel data)
I try to ...
