Questions tagged [python]

Python is a dynamic and strongly typed programming language designed to emphasize usability.

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Install py-solc-x using python, there is an error

I am using python to install py-solc-x, but there is an error during installation: [root@localhost ~]# python3 -m solcx.install v0.4.25 ERROR: Unknown option --version /usr/local/python3/lib/python3....
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2answers
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Execute from truffle dev to python language

I successfully execute smart contract function in the truffle development console, for example: let instance = await MetaCoin.deployed() let accounts = await web3.eth.getAccounts() instance.sendCoin(...
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Updating local variable across http efficiently [closed]

So a bad way to do what I want to do is this while(True): challenge_number = http(request) # where the value is subject to change miner(challenge_number) If challenge_number across http ever ...
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1answer
28 views

Execute smart contract function on python

so I already successfully make a smart contract and deployed it on my BC network. I can execute the function using the Ethereum wallet. My question is, how can I execute the functions on Python ...
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1answer
21 views

Withdraw ether from other miner

I'm working with blockchain ethereum private network with several miners. I already successfully send and stamp a transaction from (example) one minerA to minerB using web3 library in python language. ...
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3answers
37 views

Get method signature from contract rather than manually constructing

Is there a way to get a method signature from the contract object (using Web3.py) rather than manually constructing it? I don't see a function in there that accomplishes this. It seems like ...
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0answers
13 views

Call contract method via raw transaction in python

From what I've read online I can't call the method I want to in python using contract.functions.myfunc(param1,param2 becaues infura doens't support these types of transactions. So instead I want to ...
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1answer
15 views

Verify ethereum signed message using python

Is there any way to verify signed message using python? Google do not provide any useful info. I don't believe that there are no any lib which can do it. Any suggestions? Many thanks!!!
3
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1answer
61 views

Internal Trace Transactions Python

I've been trying to figure out the best way to get the Net internal/trace transactions using python for a specific transaction hash. I have read other topics on the forum that say that these are not ...
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2answers
23 views

Sending ether from list of addresses with web3.js

I would like to read the csv text file and make a transaction via web3.js like what I did with web3.py Here is my python code #!/usr/bin/python3.7 import os import time import pandas as pd from ...
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0answers
19 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 ...
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2answers
56 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?
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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 ...
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20 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', '...
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28 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":...
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0answers
36 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 ...
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1answer
60 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 ...
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1answer
108 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 ...
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0answers
28 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: "...
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0answers
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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 ...
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1answer
130 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 ...
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1answer
70 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....
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1answer
38 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 ...
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1answer
44 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 ...
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0answers
42 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. ...
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1answer
37 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 ...
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0answers
24 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-...
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0answers
36 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=...
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0answers
17 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/...
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0answers
36 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
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1answer
531 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 ...
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0answers
29 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, ...
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71 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 ...
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1answer
115 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
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1answer
104 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 ...
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1answer
138 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'))...
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1answer
151 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 ...
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1answer
182 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(...
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0answers
158 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 : /...
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1answer
356 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; } ...
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0answers
87 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 ...
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1answer
186 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 ...
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0answers
53 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-...
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1answer
487 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 ...
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2answers
162 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 ...
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2answers
43 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
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1answer
54 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')
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0answers
148 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 ...
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1answer
101 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 ...
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1answer
858 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 ...

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