Questions tagged [contract-invocation]

Questions regarding the act of calling or interacting with (a.k.a. invoking) a contract on the Ethereum blockchain by a user or another contract on the blockchain. Includes both local invocation by call and global invocation by transaction.

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Solidity - can I predict reverts?

I have a voting system and admin groups contracts. Each admin group (it contains array of addresses allowed to vote) can grab a voting contract and vote for changing code in my contracts environment. ...
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How can I retrieve the ETH stored in the contract for a now invalid ENS domain name?

A couple years ago, I bid on a domain name through the Ethereum Name Service (ENS) that is not valid, as it is considered a subdomain. For example, something like "apple.uk.eth" which should not be ...
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Gas required exceedes allowance when invoking a pure function

So, I got a problem when interacting with a smart contract in geth. I have this very simple contract: pragma solidity^0.6.1; contract Simple{ uint256 public number = 1; constructor() public { ...
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Token Sale Smart Contract

I am new to Ethereium Block Chain and have been trying some code written in solidity as follows. pragma solidity ^0.5.0; import "./MyERC20Token.sol"; import "./ERC20Burnable.sol"; contract ...
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Trouble deploying one contract from another

Why creating a contract new RewardCourts() in another contract takes more than ten kilobytes of bytecode in the contract it is called from? (It makes bytecode too big and I can't deploy it!) What to ...
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Gas Estimation Failed error when scheduling Aion call

I am trying to understand the Aion scheduling system, so I tried their code example from here. Below is the code snippet: pragma solidity ^0.4.24; // interface Aion contract Aion { uint256 ...
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2answers
71 views

How to withdraw DAI from DSR (Oasis Saving Dapp / MakerDao) using the contract only, not the Dapp frontend?

I am currently testing the Oasis Saving Dapp by MakerDao (https://oasis.app/save). After converting some DAI to DSR, users can earn savings and whenever they want, withdraw their funds (convert back ...
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How to call function from SmartContract?

I have a smart contract deployed having the following function. function getTime() public view returns (uint){ return now; } However, when I try to call the function like this. ("einstance"...
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If I use a factory contract to create a new contract, does it show that the factory contract created it in the blockchain? [closed]

I am not sure if it would show my address or the factory contract's address (or both).
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1answer
24 views

web3py - Sending a transaction to a payable contract function

I have deployed a smart contract dthat contains a payable function fundit(address _to). Now I am trying to use a Contract object to send ether to the function: tx_hash = instance.fundit....
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26 views

Execute transaction Approve directly against contract address (without ABI)

Solved For now, you will always need the ABI to execute a call against the ethereum network with web3. A simple way is to reconstruct the function you wish to execute is to, either create a separate ...
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26 views

Payable function that returns value: when is this example practical?

To quote an example from a book: contract StockPriceOracle { uint quoteFee = 500; mapping (string => uint) private stockPrices; //... function getStockPrice(string _stockTicker) payable ...
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How to read data returned by a function? [duplicate]

Counter.sol: pragma solidity >=0.5.0 <0.7.0; contract Counter { uint public _counter = 0; function GenNextID() public returns (uint) { return _counter++; } } I use ...
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Infura Json RPC: how to call a function passing parameters?

IMPORTANT My final goal is receive data via api on a php server and use Infura to call my contract to save the data Test Situation having this test contract on rinkeby contract test008 { ...
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22 views

What is the data field in eth_call commands for USDT?

I'm trying to use eth_call to send USDT (TetherToken) from one account to another (Although I know that eth_call just simiulate such transaction). Everything is clear in this regard, just the data ...
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71 views

the tx doesn't have the correct nonce. account has nonce of: 12 tx has nonce of: 3 - Ganache

I am trying to run my simple contract with different parameters (in the form of encoded signatures) and intends to put multiple transaction into ONE block. If I set Ganache GUI with automine option, ...
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192 views

MetaMask verification screen doesn't show amount or token when I use 'approveAndCall' to transfer tokens to a contract

When I use 'approveAndCall' to transfer tokens to a contract, the MetaMask verification screen doesn't show the amount, or the token name. let contract = new web3.eth.Contract(gsERC20abi, '...
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41 views

The method eth_sendTransaction does not exist/is not available, when using Ropsten Network

My following code previously works perfectly at Ganache, but when i switched it to Ropsten Network, it give captioned error. Here is Code: async function finalSettersFunctions(){ var myFunc; ...
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Is the ABI required to call a contract with ethers.js?

From the docs: // The Contract interface let abi = [ ... ]; // Connect to the network let provider = ethers.getDefaultProvider(); // The address from the above deployment example let ...
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2answers
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How to insert multiple transactions into One Block in Ganache GUI

Is it possible to enable Ganache GUI to put multiple transactions into ONE block ?. The details about Why i need this thing, is given below; I am going to test Transaction Order Dependence (TOD) ...
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1answer
18 views

How to pass encoded parameters to call contract getter fuctions

I have an array (i.e. functionNames[]) of getter functions's names of my contract and another array (i.e. finalGettersParams) of encoded parameters (which has been populated from web3.eth.abi....
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33 views

How to print the value of encoded getter functions of contract

UPDATED: Sorry for Inconvenience, I have updated all my question and accept my apology , being naive user. I have encoded getter functions of my contract i.e. ...
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3answers
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Smart contract execution without making transaction on ethereum blockchain

If I as a user of a smart contract ,call a function which does a heavy computation but doesn't change anything except the function variables which live only during function execution and then thrown ...
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29 views

How can execute function that send ether in geth console?

I want to execute the send function that sends ether from the sender to the receiver, the code is as shown below. contract Sender { function send(address _receiver , uint amount) public ...
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What is the ethersjs equivalent of `web3.eth.call` in web3js?

web3.js has the ability to call a transaction and get return data without sending a transaction: web3.eth.call(callObject [, defaultBlock] [, callback]) ethersjs apparently does not have this ...
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How does specifying job parameters on Chainlink work?

I am trying to understand Chainlink, and I am running into a wall. I found this tutorial, which explains how I can create a job spec using JSON. The tutorial explains that you can specify the url, ...
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How to check current status of state variables

I have deployed my contract locally into Ganache (GUI) and then send/call lot of transactions. After these transactions, now I want to check the current status of all state variables. Is there any way/...
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Did I get this right that with delegatecall the msg.sender is the last entity that calls delegatecall (example below)?

In other words: If contract B is called by contract A: B: function externalcall() public { //msg.sender is contract A... msg.sender.call.value(0); } Then assuming msg.sender.call above calls back ...
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Cannot use delegatecalls in Remix since either the addresses aren't displayed correcly or I cannot access the memory address?

For instance delegatecall to the same address works: function callTheOtherContract() public { require(address(this).delegatecall(bytes4(keccak256("callMe()")))); } event CallMe(...
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Is there a way for a function to perform some code to a point and then revert without conditions (more details below…)?

I want to create a payable function that acts similarly to onlyowner modifier, or: function owner() public payable{ if(msg.sender != owner) { balances[owner] += msg.value; revert(); } } What ...
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1answer
20 views

How to call a write function of contract from Dapp?

I have created a smart contract in which a "stop()" function should be called once a deadline is reached. Dapp is keeping check of the deadline and as soon as the deadline is reached I need to call ...
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15 views

So can I simply send ether to a contract as if it's a regular wallet, even without payable function?

Are contracts really that different? I guess in theory every contract should have a private key somewhere + it should be possible to send ether to it? Unless geth/parity and other parts of the evm don'...
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REMIX debugger invalid opcode before JUMP

I am testing simple ERC20 token creation with the following in remix: pragma solidity ^0.5.0; import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v2.4.0/contracts/token/ERC20/ERC20....
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Calling function on ERC20 contract through staticcall gives wrong result

I've made two functions to interact with a local ERC20 token. Here they are: pragma solidity ^0.5.0; contract GardenTestContract { function getBalanceOf(address _address) public view returns (...
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18 views

Dataset of simple contracts with getter setters

Are there any repositories/datasets which provide smart contract with simple logic like having some getters and setter functions. So, that I could give some values to getter and setter functions, ...
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41 views

Calling contract functions using only ABI without source code

I have MyContract.json file of some contract(assume i haven't its source code). In .json file, there is abi and bytecode. If i want to deploy such contract (through web3js), I am facing following ...
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1answer
31 views

How to call external payable contract function from app.js (DApp)?

The contract has a function: function purchaseTokens() external payable { require(msg.value>0); ...etceteras... } What I need is an app.js part, something that would look like this (lets ...
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1answer
22 views

How to know the execution time of transaction when miner execute it

When i send three consecutive transactions to my contract (deployed on ethereum testnet), how can i know the exact time (at milli/micro/nano level) which transaction executed (on miner side) first and ...
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1answer
30 views

State Variable of solidity Contract could not be updated through JavaScript

I have following contract and just want to update its state variable values i.e. totalSupply. But when I try to attempt this task through JavaScript code (given below) by calling its function i.e. ...
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3answers
34 views

Could not assign contract state variable value to javascript variable

I want to retrieve and assign the value of my contract state variable to my javascript variable.I am doing as per guidlines provided on this community, but failed to assigned. my javascript code is ...
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1answer
31 views

Get Contract Address by It's ByteCode

I have some bytecode and would like to find the contract address that it belongs to. Is there an easy way to do this?
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Two calls to a contract: input of the first can only be revealed after the second call

I see that there are no parallel execution in EVM. The problem I am trying to solve is the following: I have a contract which takes the input of two parties -- say users A and B. The result of the ...
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1answer
16 views

AttributeError while trying to call a contract using web3py and Infura

I am trying to call a function from an already-deployed contract on the Ropsten network: from web3 import Web3 infura_url = "https://ropsten.infura.io/v3/XXXXXXXXXXXXXX" w3 = Web3(Web3.HTTPProvider(...
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92 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
25 views

Creating a contract instance

Is it generally better to define a contract instance once, then pass it through your components like... class Parent extends React.Component{ constructor(props){ super(props); ...
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Why is it required to know the function selector in a smart contract to call the function? [duplicate]

I understand what a function selector is and how it is computed: The first four bytes of the call data for a function call specifies the function to be called. It is the first (left, high-order ...
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2answers
33 views

How do i use .send() to fire methods of my smartcontract?

I have looked alot for information about this and lastly i turn myself to here. I've written a smartcontract and deployed it to Ropsten . I am then using web3.js to interact with my smartcontract, i ...
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1answer
80 views

Linked contracts not running on go-ethereum

A very simple linked contracts example where A contract has a variable and B contract queries the A contract's variable is running ok on Ropsten+myetherwallet and Remix sandbox, but it fails when ...
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1answer
60 views

Need a guide to access my ropsten test network contracts through my command line and not remix

I have written and published a contract on the ropsten test network using remix. Now I want to access the functions of the smart contract from my command line (My PC) and not the remix IDE. Is there a ...
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1answer
18 views

What are the ways to call a smart contract function during development?

What are the ways to call a smart contract function during development using Truffle simulated VM with a GUI interface (like Remix or EtherScan offer)? I know I could use CLI options like Truffle ...

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