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QUESTION
I am new to blockchain app development, I saw a project where ganache accounts are imported into Metamask, then web3.js is used to access and print those accounts and balances on Frontend (user interface).
If web3.js can directly access ganache blockchain accounts and balances, why do we need Metamask in between?
ANSWER
Answered 2022-Feb-08 at 09:11If web3.js can directly acccess ganache blockchain accounts and balances, why we need metamask in between?
In this case, you don't need MetaMask to sign the transaction, as the node (Ganache) holds your private key.
But in a public environment (testnets and mainnet), the node doesn't hold your private key, so you'd need to sign the transaction using MetaMask (or any other tool that holds the private key).
QUESTION
I tried https://docs.opensea.io/reference opensea.io docs to fetch data. However, I think there are 2 APIs.
curl --request GET \
--url https://api.opensea.io/api/v1/asset/0xb47e3cd837ddf8e4c57f05d70ab865de6e193bbb/1/
This is for a single asset and it requires a token id as well. But I want data of all the NFTs of a particular smart contract address just by giving the smart contract address.
And this is for a single contract.
curl --request GET \
--url https://api.opensea.io/api/v1/asset_contract/0x06012c8cf97bead5deae237070f9587f8e7a266d
ANSWER
Answered 2021-Aug-04 at 15:03The assets
endpoint (docs) has the asset_contract_address
filter that allows you to filter by a contract address. Which will effectively allow you to paginate through all NFTs of the contract (that Opensea knows of).
Example:
curl 'https://api.opensea.io/api/v1/assets?offset=0&limit=20&asset_contract_address=0xb47e3cd837ddf8e4c57f05d70ab865de6e193bbb'
QUESTION
I want to publish files on ipfs but it's showing me an error.
Here is my code...
const ipfsClient = require('ipfs-http-client');
const ipfs = ipfsClient({host: 'ipfs.infura.io', port: 5001, protocol:
'https'});
function App() {
const [buffer, setBuffer] = useState();
const handleChange = (event) => {
event.preventDefault();
const file = event.target.files[0];
const reader = new window.FileReader();
reader.readAsArrayBuffer(file);
reader.onloadend = () =>{
setBuffer(reader.result);
}
}
const handleSubmit = async(event) => {
event.preventDefault();
console.log('submitting...')
await ipfs.add({buffer}, (error, result) => {
console.log('ipfs results');
if(error){
console.error(error);
return;
}
});
}
I am getting this error in browser...
TypeError: ipfsClient is not a function
ANSWER
Answered 2021-Nov-11 at 04:27I am not familiar with ipfs but i checked the official docs and they have done the first line like this:
const { CID } = require('ipfs-http-client')
Those brackets are essential
QUESTION
I have been trying to interact with a contract on the AVAX chain using web3js and it keeps throwing the error, "TypeError: Cannot read properties of undefined (reading 'send')". I cannot figure out why this is happening, as it should be a valid statement. If anyone can help that would be awesome.
const contract = new Contract(*abi*, '0x82194f7d4Ded53A546ec4e3A7a57f81C5a54E194');
console.log("transaction sent");
await contract.methods.transfer(address, amount).send({to: "0xxxxxx"});
console.log("transaction sent really");
}
Also, is it acceptable to paste the abi directly into the constructor in between [] brackets, like so? const contract = new Contract(*abi*, '0x82194f7d4Ded53A546ec4e3A7a57f81C5a54E194');
Here is the Contract ABI
"status": "1",
"message": "OK",
"result": "[{\"inputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"constructor\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"owner\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"spender\",\"type\":\"address\"},{\"indexed\":false,\"internalType\":\"uint256\",\"name\":\"value\",\"type\":\"uint256\"}],\"name\":\"Approval\",\"type\":\"event\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"previousOwner\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"newOwner\",\"type\":\"address\"}],\"name\":\"OwnershipTransferred\",\"type\":\"event\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"from\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"indexed\":false,\"internalType\":\"uint256\",\"name\":\"value\",\"type\":\"uint256\"}],\"name\":\"Transfer\",\"type\":\"event\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"owner\",\"type\":\"address\"},{\"internalType\":\"address\",\"name\":\"spender\",\"type\":\"address\"}],\"name\":\"allowance\",\"outputs\":[{\"internalType\":\"uint256\",\"name\":\"\",\"type\":\"uint256\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"spender\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"amount\",\"type\":\"uint256\"}],\"name\":\"approve\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"account\",\"type\":\"address\"}],\"name\":\"balanceOf\",\"outputs\":[{\"internalType\":\"uint256\",\"name\":\"\",\"type\":\"uint256\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"uint256\",\"name\":\"amount\",\"type\":\"uint256\"}],\"name\":\"burn\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"account\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"amount\",\"type\":\"uint256\"}],\"name\":\"burnFrom\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[],\"name\":\"decimals\",\"outputs\":[{\"internalType\":\"uint8\",\"name\":\"\",\"type\":\"uint8\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"spender\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"subtractedValue\",\"type\":\"uint256\"}],\"name\":\"decreaseAllowance\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"spender\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"addedValue\",\"type\":\"uint256\"}],\"name\":\"increaseAllowance\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"amount\",\"type\":\"uint256\"}],\"name\":\"mint\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[],\"name\":\"name\",\"outputs\":[{\"internalType\":\"string\",\"name\":\"\",\"type\":\"string\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[],\"name\":\"owner\",\"outputs\":[{\"internalType\":\"address\",\"name\":\"\",\"type\":\"address\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[],\"name\":\"renounceOwnership\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[],\"name\":\"symbol\",\"outputs\":[{\"internalType\":\"string\",\"name\":\"\",\"type\":\"string\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[],\"name\":\"totalSupply\",\"outputs\":[{\"internalType\":\"uint256\",\"name\":\"\",\"type\":\"uint256\"}],\"stateMutability\":\"view\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"amount\",\"type\":\"uint256\"}],\"name\":\"transfer\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"from\",\"type\":\"address\"},{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"amount\",\"type\":\"uint256\"}],\"name\":\"transferFrom\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"newOwner\",\"type\":\"address\"}],\"name\":\"transferOwnership\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\"}]"
}]```
ANSWER
Answered 2022-Mar-19 at 17:10The ABI needs to contain just the function and event definitions that are stored in your result
property. Without the wrapper object containing status
and other properties.
So in your case
const abi = [{"inputs":[],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"spender","type":"address"},{"indexed":false,"internalType":"uint256","name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"previousOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":false,"internalType":"uint256","name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"spender","type":"address"}],"name":"allowance","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"approve","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"burn","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"account","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"burnFrom","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"subtractedValue","type":"uint256"}],"name":"decreaseAllowance","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"addedValue","type":"uint256"}],"name":"increaseAllowance","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"mint","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"renounceOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transfer","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transferFrom","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"nonpayable","type":"function"}];
QUESTION
I've been using the testnet lately and I encounter issues: they reset it very often and the service is down for multiple hours and sometimes have bugs.
Should I use the devnet? From what I've understood it's more stable and they reset it less often?
I have a backend in js that uses the elrond-sdk-erdjs and I'm confused because there is no function that initializes the https://devnet-gateway.elrond.com only the testnet. Is there a reason?
// TODO: Adjust with respect to current terminology (localnet instead of devnet).
function getDevnetProvider() {
return new proxyProvider_1.ProxyProvider("http://localhost:7950", { timeout: 5000 });
}
exports.getDevnetProvider = getDevnetProvider;
function getTestnetProvider() {
return new proxyProvider_1.ProxyProvider("https://testnet-gateway.elrond.com", { timeout: 5000 });
}
exports.getTestnetProvider = getTestnetProvider;
function getMainnetProvider() {
return new proxyProvider_1.ProxyProvider("https://gateway.elrond.com", { timeout: 20000 });
}
ANSWER
Answered 2021-Aug-24 at 12:56The testnet is pretty volatile and it is reset very often (maybe weekly), without any warnings. Elrond recommends developers to use the devnet, it is reset maybe once every 3-4 months, so it's more stable.
You can get the provider like this:
function getDevnetProvider() {
return new proxyProvider_1.ProxyProvider("https://devnet-gateway.elrond.com", { timeout: 5000 });
}
And the devnet explorer is here: https://devnet-explorer.elrond.com/
QUESTION
Hey guys I am trying to deploy my project on the rinkeby chain using infura, but I am getting a ValueError Here is my trackback:
INFO: Could not find files for the given pattern(s).
Brownie v1.17.1 - Python development framework for Ethereum
File "c:\users\allow\appdata\local\programs\python\python39\lib\site-packages\brownie\_cli\__main__.py", line 64, in main
importlib.import_module(f"brownie._cli.{cmd}").main()
File "c:\users\allow\appdata\local\programs\python\python39\lib\site-packages\brownie\_cli\run.py", line 44, in main
network.connect(CONFIG.argv["network"])
File "c:\users\allow\appdata\local\programs\python\python39\lib\site-packages\brownie\network\main.py", line 40, in connect
web3.connect(host, active.get("timeout", 30))
File "c:\users\allow\appdata\local\programs\python\python39\lib\site-packages\brownie\network\web3.py", line 52, in connect
uri = _expand_environment_vars(uri)
File "c:\users\allow\appdata\local\programs\python\python39\lib\site-packages\brownie\network\web3.py", line 183, in _expand_environment_vars
raise ValueError(f"Unable to expand environment variable in host setting: '{uri}'")
ValueError: Unable to expand environment variable in host setting: 'https://rinkeby.infura.io/v3/$WEB3_INFURA_PROJECT_ID'
Here is my deploy.py code
from brownie import accounts, config, SimpleStorage, network
import os
def deploy_simple_storage():
account = get_account()
simple_storage = SimpleStorage.deploy({"from": account})
stored_value = simple_storage.retrieve()
print(stored_value)
transaction = simple_storage.store(15, {"from": account})
transaction.wait(1)
updated_stored_value = simple_storage.retrieve()
print(updated_stored_value)
def get_account():
if network.show_active() == "development":
return accounts[0]
else:
return accounts.add(config["wallets"]["from_key"])
def main():
deploy_simple_storage()
I have a really little experience in coding. I think the problem is related to .env, but I don't know what I should now. FYI I am using windows n follow this course https://www.youtube.com/watch?v=M576WGiDBdQ stuck at 4:48:00
ANSWER
Answered 2021-Nov-28 at 10:14it appears your env variables are not set correctly, and it looks like in this case it's your WEB3_INFURA_PROJECT_ID.
You can fix it by setting the variable in your .env file and adding dotenv: .env to your brownie-config.yaml.
brownie-config.yaml:
dotenv: .env .env:
export WEB3_INFURA_PROJECT_ID=YOUR_PROJECT_ID_HERE Remember to save these files.
Additionally, you should be on at least brownie version v1.14.6. You can find out what version you're on with:
brownie --version
QUESTION
I am very new to blockchain programming and programming in general. I want to generate my SOL address using the mnemonic seed phrase with the derivation path "m/44'/501'/0'/0". I can't find a proper BIP44 module for python where you can specify the derivation path.
ANSWER
Answered 2022-Feb-23 at 00:41After a long search through the internet, I have finally found a way of solving my problem that I want to share with you.
from bip_utils import *
MNEMONIC = "...12 words phrase..."
seed_bytes = Bip39SeedGenerator(MNEMONIC).Generate("")
bip44_mst_ctx = Bip44.FromSeed(seed_bytes, Bip44Coins.SOLANA)
bip44_acc_ctx = bip44_mst_ctx.Purpose().Coin().Account(0)
bip44_chg_ctx = bip44_acc_ctx.Change(Bip44Changes.CHAIN_EXT)
print(bip44_chg_ctx.PublicKey().ToAddress())
This code outputs the first address of your mnemonic. This is only for Sollet and Phantom wallet!
If you are using Solflare you can cut the line bip44_chg_ctx = bip44_acc_ctx.Change(Bip44Changes.CHAIN_EXT)
out!
QUESTION
ANSWER
Answered 2021-Oct-18 at 02:20I had the same issue but then I installed with npm and it worked
npm install -g ganache-cli
QUESTION
enter image description hereI've installed latest version of visual studio with desktop development c++ workload but still they are asking for it when i try to install truffle. I entered command :npm install -g truffle and lot of messages appear after 2 to 3 minutes of some kind of installation process. they are asking for Latest version of Visual Studio with "Desktop development with c++ workload" whereas i just installed my Visual studio with the same requirements. node.js and ganache are already installed. Is there any other way to install truffle?
ANSWER
Answered 2022-Feb-17 at 16:59If you are installing it using npm package manager. Downgrade your npm to 7.24.2 it worked for me I hope it will also work for you. Use the following command to downgrade npm
npm install -g npm@7.24.2
QUESTION
I'm trying to swap tokens on uniswap unsing hardhat's mainnet fork but I'm getting this error: Error: Transaction reverted without a reason string
. And I don't really know why.
Here is my swap function:
function swap(address router, address _tokenIn, address _tokenOut, uint _amount) public {
IERC20(router).approve(router, _amount);
address[] memory path;
path = new address[](2);
path[0] = _tokenIn;
path[1] = _tokenOut;
uint deadline = block.timestamp + 300;
IUniswapV2Router(router).swapExactTokensForTokens(_amount, 1, path, address(this), deadline);
}
It is a simple function and it should work. This is how I'm calling it:
await arb.swap(
uniAddress,
wethAddress,
daiAddress,
ethers.utils.parseEther('0.5')
);
Thanks for answers!
Also here are the addresses I'm calling just to verify if they are the right ones but I'm pretty sure they are:
const wethAddress = '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2';
const daiAddress = '0x6B175474E89094C44Da98b954EedeAC495271d0F';
const uniAddress = '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D';
ANSWER
Answered 2022-Feb-17 at 06:46Weth
is different from other token, you're not able to use swapTokensForTokens
. We must use the swapEthForTokens
function instead, and you have to declare the data option separately.
so in your case we need to do:
Solidity code:
function swapEth(address router, address _tokenIn, address _tokenOut, uint _amount) public {
IERC20(router).approve(router, _amount);
address[] memory path;
path = new address[](2);
path[0] = _tokenIn;
path[1] = _tokenOut;
uint deadline = block.timestamp + 300;
IUniswapV2Router(router). swapExactETHForTokens(... parameters);
}
JSCode
const dataOption = { gasPrice: ethers.getDefaultProvider().getGasPrice(), gasLimit: 310000, value: ethers.utils.parseEther('0.5') }
await arb.swap(`enter code here`
uniAddress,
wethAddress,
daiAddress,
ethers.utils.parseEther('0.5'), // this parameter should be remove from the function declaration as well as in this Javascript
dataOption
);
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