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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502 views

How to call a contract function using Nethereum?

I would like to call a contract function using Nethereum C#. Here is the contract in Etherscan (https://etherscan.io/token/0x8c9b261faef3b3c2e64ab5e58e04615f8c788099#readContract) I want to call ...
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Limit the number of times a static function is called

As far as I am concerned, when a function in a smart contract is defined as pure or view it is possible to invoke it without being charged for the gas consumption that its execution requires. This ...
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0answers
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Solidity: Creating contracts with contracts by “new” operator

I'm creating "Trade" contract inside "Token" contract. I used an array to store each "Trade" contracts. Used web3, truffle. Token.sol: mapping (address => Trade[]) private _Trade; event tradeMade(...
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2answers
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state variable value not changing

I have very simple solidity code as below - pragma solidity ^0.5.6; contract SaveData { uint public salary; function setSalary(uint input) public { salary=input; } function ...
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1answer
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Can't return string when function not pure? [duplicate]

See the below contract function of which return the string (Tested in Remix.org): pragma solidity >=0.4.22 <0.6.0; contract HelloWorld { function get() pure public returns (string memory){ ...
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1answer
619 views

Deploying and calling a contract works only with Ganache (not with Geth)

I deployed a HelloWorld contract using web3j and it worked awesome with Ganache. I was able to call my only function from the contract and it returns the desired result all the time. When I deploy ...
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1answer
97 views

Difference between ERC20 and ERC223

i still don't get the idea behind the "if you send 100 ERC20 to a contract, they're stuck there and these 100 ERC20 are lost forever".. i really don't get.. like, a contract has an address and a ...
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How much data can I store in a smart contract, what is the cost and how it is implemented?

If I suppose I use a smart contract as a database, how much data can I store? speaking only of strings and integers, save them in contract data structures does it cost in addition to the gas used for ...
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2answers
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Verify transfered amount of two transactions from same ERC20 to same Contract

I making a contract to sell stuff in a decentralized way and want to use following method to transfer founds. function transferToken(address token, address from, uint256 amount) internal { IERC20 ...
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160 views

How do I send a transaction to a smart contract?

I need to build this transaction and send it to the blockchain how do I do it ? I always used ethsendrawTransaction just to send eth but never I never built this type of transaction: { "data": [ ...
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131 views

Is it possible for a smart contract to relay raw signed transaction

I am rethinking the flow for token transfer and confirmation on the network (ERC20,ERC721...). I am unaware of a way presently to: 1- transfer tokens and 2- trigger a call in different contract, ...
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web3j.ethCall returns null when retrieven contract variable

Environment: Geth node Geth/v1.9.0-unstable/windows-amd64/go1.12 Commands used to start the node to mine: geth --datadir "." --networkid 101 -verbosity 6 --port 30301 --rpcport 8101 --nodiscover -...
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How can Contracts sign transactions, when they dont have a private key?

When transactions are made the sender is identified by his signature. But Contracts dont have a private key to sign any transaction or message. So I have some questions: Can a Contract initiate a ...
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Can events always be called directly by user accounts? Is there a way to make them internal?

I am using events to fire an order, basically using them as a vehicle for a master/slave connection with an IoT device, through the blockchain. Ideally i want to always verify the right msg.sender is ...
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if the smart contract has terms to be met in a time order and transactions corresponding to the terms, what happen when two different users [closed]

if the smart contract has terms to be met in a time order(assuming in one year time frame) and transactions corresponding to the terms, what will happen to the variables stored in the contract account ...
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2answers
116 views

two of transactions initiating the same smart contract in one block during state transition cycle, what happen?

if two of transactions initiating the same smart contract in one block during state transition cycle, what will happen to the contract account balance and the variables(or data) changes through ...
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1answer
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Is it possible to get a function's original returndata if it is wrapped in an interface that doesn't return anything?

Will a function's returndata persist through a wrapper, even if the wrapper does not support a return value? An example would be as follows: contract OriginalContract { function originalFunction()...
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1answer
37 views

Where is the position of each paramter in a smart contract function when encoded as inputdata in a transaction

When I reviewed the BEC attack, I found the position of each parameters value in real transaction was not corresponding in to definition of function in smart contract. The exploit transaction is at: ...
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1answer
55 views

What is the advantage and disadvantage of deploying Erays on Ethereum?

I have read this paper, Erays: Reverse Engineering Ethereum's Opaque Smart Contracts. They proposed this reverse engineering tool for Ethereum smart contracts. it will take as input a compiled EVM ...
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1answer
25 views

Can transaction fail after being sent?

I wonder what would happen in following hyphotwtical scenario. Transaction is being sent with blockchain state A. In this state transaction consume 100_000 gas and sender has enough funds to pay for ...
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0answers
14 views

How the following scenario be achieved using smart contracts?

Assuming we have two parties (A & B). How the following scenario be achieved using smart contracts? User A will deposit some funds (x coins). user A can receive penalty funds from user B, So user ...
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Condition for changing a smart contract

I'm developing an application using smart contracts. I wonder if it is possible to establish different states for a contract, for example: User 1 determines a condition X, but also determines that ...
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69 views

Hot to debug a contract method invocation?

Running this code: PrintProofOfWork.methods.printRequested(gcodeHash).send({from: web3.eth.defaultAccount}) .then((result) => { console.log(`result of the invocation: ${...
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Contract deployment not working anymore

So I have this following code that was working a couple of weeks ago and today I decided to run a few tests and it just doesn't do its job anymore. function approve(rid, guest_wallet, ctr_key, dti, ...
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1answer
161 views

Calling another contracts function -minimum info required

I understand how to call another contracts function. My question is, if I want to use an interface like in this question over call(): Call function on another contract contract Name { mapping(...
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1answer
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Is it possible to have a contract run whenever a wallet address receives a transaction?

I'd like to build some code that monitors a wallet address, and performs an action whenever that wallet receives a transaction. I could do this with say javascript or whatever, but that doesn't offer ...
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1answer
71 views

ERC223 and ERC827 can receive erc20 tokens and call a function immediately?

As the title says, is that possible? For example on my ico contract, I accept USDT erc20 token and when I receive each transaction, call a function for that and send that address my tokens or eth.
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101 views

get bytecode in smartcontract ? possible?

is it possbile to get bytecode of already deployed contract on another contract? example : get bytecode of contract A using contract B (using solidity )
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Code Example from “Mastering Ethereum: Building Smart Contracts and DApps” doesn't work

I'm reading the Ethereum book of Gavin Wood right know and the following code example gives an error message when I try to compile it with truffle: pragma solidity ^0.4.22; contract calledContract { ...
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2answers
55 views

Including an owner address based automated routine execution in a React ethereum dapp?

As I understand, all the front-end components for a react based ethereum dapp are rendered from the point of view of the user's metamask default account. All the calls to constant functions in ...
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1answer
89 views

Benchmarking energy usage of executing smart contracts

I'm working on a project that will allow for me to benchmark of the top ten most popular smart contracts which I'll take from EtherScan. The idea of the project is to determine if the smart contract ...
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1answer
156 views

Public smart contract that calls Private contract API

In a private blockchain (e.g, quorum), assume that I have a peer X and peer Y. X has a private smart contract (A) and Y has a public smart contract B. Assume that A provides an API for Y in order to ...
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2answers
35 views

Call to smartcontract without address

Lately I had a conversation with someone who says that it is possible to make a call to the smart contract without giving the address. He said it's possible to send certain parameters and by them the ...
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Replaying the Bad Parity Hack

On a locally hosted instance of Ethererum I am trying to replay and understand the Bad Parity hack. I have a Wallet and a Wallet Library Contract. Wallet.sol constructor(address lib) public payable {...
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38 views

How does one go about implementing the ContractTransactor interface from the bind package in go-ethereum?

Hey guys thanks in advance! Here is the interface provided by the go-ethereum library in the bin package. I need an example on how to implement this interface please :) // ContractTransactor ...
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3answers
106 views

What other constants depend on the current call like msg.sender?

I recently noticed that msg.sender isn't always the original caller's address (see here). It's the address of the current call. So if foo() calls bar(), then msg.sender in bar() will be the address of ...
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1answer
64 views

How to burn non burnable ERC20?

Suppose you received 250 HELLOCoins and you want to burn them. Unfortunately, HELLOCoins uses OpenZeppelin ERC20 which implements the following function: function _transfer(address from, address to,...
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1answer
281 views

truffle-contract: Contract has not been deployed to detected network (network/artifact mismatch)

I am running a private network and would like to use truffle-contract to interact with the contracts. Unfortunately it gives me this error: Error: Contract has not been deployed to detected network (...
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2answers
683 views

truffle-contract error: Number can only safely store up to 53 bits

I am using truffle-contract with a local quorum node and try to execute a smart contract method, but getting this error: Error: Number can only safely store up to 53 bits That's the way I do it: ...
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1answer
53 views

Interacting with Already deployed Ethereum Contract and recording response

I understand this topic has been discussed before, but my question is specific to web3.py. How can I interact with function of already deployed ethereum contracts on Ropsten TestNet. my code runs with ...
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1answer
94 views

How can a peer request another peer to invoke a function from his private contract

I build a permissioned network using Quorum, I have a peerA which has a private smart contract, another peerB that cannot invoke functions of the smart contract as it is private So, can peerB send ...
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0answers
55 views

state channel between smart contracts

In my scenario, there are data sellers and data buyers which might be persons or organizations. I would like to create a smart contract for data seller and another smart contract for data buyer where ...
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1answer
247 views

How can I call contract method that suicide and continue execution?

Can I call another contract that eventually will call selfdestruct, and keep executing my function? For example, say I have two contracts as follows: contract Destructor { address owner; ...
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1answer
180 views

web3.py locally signed transaction rejected because of invalid nonce

I'm trying to sign locally a transaction to a smart contract method using web3.py. I'm using ganache and there is one interesting issue when I send a transaction as the contract deployer everything ...
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1answer
131 views

what is the equivalent of encodeFunctionSignature for web3.js version ^0.20.6

I want to check if a specific contract deployed at an address is an erc721 contract. I found out that most of the erc721 contracts should have safeTransferFrom function implemented. (except ...
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1answer
179 views

Unable to schedule a call using Aion Recurring Contract

So here's the contract that I deployed on Ropsten Network. I took code refer from here. pragma solidity ^0.4.24; // interface Aion contract Aion { uint256 public serviceFee; function ...
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204 views

How msg.sender changes through relaying function calls between contracts? [duplicate]

Here is the example for question. contract example1 { function A() { print msg.sender; // just fake code to imagine it prints out the result example3.C(); } } contract example2 { ...
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1answer
183 views

How msg.sender changes through relaying function calls?

I'm confused about how msg.sender changes through relaying function calls. I know that msg.sender sets to the caller(it should be me) address at first, but through the process, msg.sender can change ...
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1answer
34 views

Metamask Web3js Synchronous Method Error

Okay guys, I'm a complete newbie to Ethereum and Web3.js and going through the Crypto Zombies tutorial and have done okay so far. But, when I use this function in my index.html file as they show it I ...
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1answer
184 views

Understand an EVM call instruction with gas as 0x00

I am trying to understand the following EVM call instruction generated from here: https://ethervm.io/decompile memory[temp3:temp3 + 0x00] = address(msg.sender).call.gas(0x00).value(var1)(memory[...

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