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Questions tagged [dapps]

Questions about applications and projects on Ethereum: a decentralized application (dapp) does not require any servers or backends and runs independent on a distributed blockchain.

26
votes
3answers
13k views

How to create a Dapp from scratch on Ethereum?

Let's say we have someone who knows about blockchain but who doesn't have any background in blockchain-based application. That person wants to code an ethereum-based Dapp (decentralized application) ...
17
votes
4answers
14k views

How do I send an arbitary message to an Ethereum address?

How can I send a message to another Ethereum address? And how would that user receiving know that its a message? Is there an Ethereum wallet that will show that I sent a message to that address? And ...
1
vote
0answers
13 views

Transaction sent from web3 cannot reached all transaction to network node

I used one node endpoint to interact with the network. While sending a transaction from web3.js 0.20 to ethereum network, transaction per second (TPS) I achieved is only 28 TPS. I have configured the ...
1
vote
1answer
44 views

Empty value (0x) returned from contract web3j

I'm trying to deploy a very simple contract on Windows 10, using Web3j 4.2.0. I've created an account using Mist. I've set up one local ethereum node (using geth) on my machine and I'm able to deploy ...
1
vote
3answers
48 views

How much does it cost to develop and run dApp on Ethereum or Hyperledger fabric?

When we develop and run a non-decentralized application it causes costs for using cloud server. How much does it cost to develop and run dApp on Ethereum or Hyperledger fabric? Which one is cheaper?
0
votes
1answer
76 views

how to call function in proxy contract

https://github.com/rayonprotocol-research/solidity-upgradable-contracts/blob/master/contracts/Proxy.sol I'm practicing proxy pattern but i dont know how to call function at logic contract from proxy ...
0
votes
1answer
10 views

can I return an address from a contract interface instead of another contract?

for example i have a contract function that returns a contract, can I define an interface that calls that function, but only returns an address? contract foo { .... .... } contract bar { ...
1
vote
1answer
26 views

Ethereum Game design idea

Is it possible to write emacs dunnet game in solidity? Not that there is any reason for the game to be on a blockchain, it is for a class assignment. I tried 2048 game. But it seems to have some ...
0
votes
1answer
256 views

Factory Contract Function is not creating New Contract using testrpc and web3

I am new to DApp development. I have deployed a TokenFactory contract and that Factory contract has a function "Create New Token" that generates a new token contract. The function "Create New Token" ...
1
vote
1answer
1k views

How do I automatically mint ERC-20 Tokens Every time the owner wallet transfers coins

I want to start with a total_supply of 1,000 Tokens in the owner wallet. Each token will represent a gram of gold. Every time 1 token is transferred from owner wallet to another wallet, the owner ...
1
vote
1answer
235 views

Watch pending transactions with ethjs.js

I am trying to use ethjs.js to listen to pending transactions, but nothing really worked. Does anyone have a working example fetching pending transactions with ethjs.js? I have tried the following: ...
0
votes
3answers
259 views

Cannot get value from calling constant function with web3js and Metamask

I have an extremely basic contract deployed on Ropsten: pragma solidity ^0.4.16; contract hypergrowth { uint256 public someNumber = 5; function hypergrowth() public {} function changeNumber(...
0
votes
1answer
31 views

How much hash power is acutally used for dapp on the ehereum network

In any given block you can see 3 eth is rewarded to the miner who found it, and 0.??? is rewarded for process transactions. Both operations require computation and storage power, but clearly finding ...
0
votes
0answers
25 views

I keep getting this error on my metamask extension “Transaction Error. Exception thrown in contract code.” [closed]

Here's my code pragma solidity ^0.4.6; contract CampaignFactory { address[] public deployedCampaigns; function createCampaign(uint minimumAmount) public { address newCampaign = new ...
0
votes
0answers
12 views

sendTransaction never resolves on web3.js 1.0.0 beta49 - beta52

My plain vanilla sendTransaction doesn't ever resolve on ganache with web3js 1.0.0 beta52: async function sendTx() { const receipt = await web3.eth .sendTransaction({ to: "0x1...", ...
0
votes
0answers
8 views

Metamask window position [closed]

Is there a way to change the position of metamask popup window? When I interact with a dapp in a browser on the third monitor metamask appears on the first monitor. This is a very irritable behavior.
0
votes
1answer
31 views

Can't create child contract in mainnet?

address[] child; function createChildContract() onlyOwner public{ address newChild = new Child(msg.sender); child.push(newChild); emit ChildCreated(newChild); } contract Child { ...
0
votes
2answers
73 views

Stack too deep, try using fewer variables [duplicate]

Seems like I'm passing a lot of arguments in a struct creation, this message error showed up "stack too deep , try using fewer variables" I tried to get rid of it by using bytes32 instead of string, ...
-2
votes
0answers
12 views

Testrpc access premissions installation error on mac os 10.14

Vineeths-Mac:~ vineeth$ npm install -g ethereumjs-testrpc npm WARN deprecated ethereumjs-testrpc@6.0.3: ethereumjs-testrpc has been renamed to ganache-cli, please use this package from now on. npm ...
0
votes
1answer
57 views

Uploading files on IPFS Infura

I am trying to make a dapp to upload files on IPFS Infura. I am using IpfsHttpClient in web browser by including the script <script src="https://unpkg.com/ipfs-http-client/dist/index.min.js">&...
0
votes
1answer
47 views

Invalid JSON Response while connecting DApp, Metamask and Backend

I am getting some error(picture below) while trying to connect DApp with a backend. One day ago, everything worked fine, now I got an error: "basic auth failure". Contracts are deployed on Ropsten ...
0
votes
2answers
354 views

Deploying a smart contract using DApp

I am new to the development of DApps on ethereum blockchain. I want to make a contract Management System in which users can generate their own tokens and crowdsale using my web application. I am able ...
0
votes
1answer
34 views

Best options to host an ethereum react dapp to a custom domain

I'm looking for best options to host an ethereum dapp created using react and drizzle, with the following requirements: It needs to be hosted in a custom domain (.com / .net / OR .io ) that I have ...
1
vote
0answers
27 views

How can I return dynamic string array in Solidity?

How can I return a dynamic string array? I came across serialization and deserialization. How can I serialize and deserialize dynamic string array ? pragma solidity ^0.5.0; contract Abc{ string[]...
0
votes
0answers
20 views

IPFS - file stored by all users

Suppose one or many users used my fully decentralized app to store different files on IPFS. How can I keep track of all file hashes by using smart contracts?
-1
votes
1answer
18 views

Fully Decentralized Dapp [duplicate]

How can I build a fully decentralized dapp where the frontend code (.html,.css,.js) and ABI files (build/contracts/json) are stored in ipfs and contracts on test-network. But I am unable to do so ...
0
votes
0answers
21 views

NuCypher for storing file securely on IPFS

Please someone guide me how I can use NuCypher Algo for storing a file on IPFS such that only a set of people can open its ipfs-hash link. Can you tell the implementation because I am finding it ...
1
vote
0answers
19 views

Smart Contract ABI in Remix (Ethereum)

When I deploy smart contract on the Rinkeby network using Remix the ABI of smart contract does not contain its address, so how do I connect it with my frontend application.
0
votes
1answer
33 views

dApp exploit using multiple wallets

Im currently building a dApp where users will create content that then can be bet on by other users. The design opens up the problem of a user creating content,logging in with another wallet address, ...
0
votes
1answer
18 views

Truffle contract.deployed does not get the latest instance deployed

I am developing a back-end DApp using truffle and nodejs on a private network. My application call Contract.deployed() and print the address of the obtained Contract. When I call truffle migrate --...
0
votes
1answer
6 views

Corporate key store for storing private keys - Ethereum

Is there a device to store private keys of Ethereum in a corporate world? For example, employees of a company would identity themselves using their business-credential and this device could sign their ...
0
votes
0answers
6 views

Instance of sol file in browser

How do I get the instance of sol in browser using js. In React it happens like: import SimpleStorageContract from '../build/contracts/SimpleStorage.json' const simpleStorage = contract(...
2
votes
1answer
62 views

TruffleContract At() function with Drizzle

I am learning the Drizzle framework after I did a project using TruffleContract abstractions in Javascript (DApp). I have multiple instances of a contract and I am not able to access at the instances ...
3
votes
1answer
261 views

Infinite loop in a view

How is ethereum network protected against infinite loops in views? In normal transaction you have to pay a gass, so it would be too expensive for you, but calls to views are for free. For example ...
0
votes
1answer
61 views

Tokenising goods and services

I am working on an dapp (private blockchain) wherein users can exchange fiat currency for a token. The token can then be exchanged for particular goods and services, for example: groceries, health, ...
0
votes
0answers
36 views

IPFS dapp hosting

I have uploaded the dapp frontend folder along with contracts json files on the IPFS using ipfs add <path> ipfs name publish <hash> commands. I am running Ganache for in-memory virtual ...
0
votes
1answer
30 views

Dapp on Ganache and Truffle but… what about Remix?

My dapp runs well with Ganache and Truffle but how to deploy with Remix and connect the contract to web GUI without abi? I mean, i created a Dapp that runs really good on Ganache and i run the web ...
0
votes
2answers
95 views

This contract collects ETH in exchange for voting tokens. What function will allow me to transfer the collected ETH to a wallet?

pragma solidity ^0.4.23; contract Voting { bytes32[] public candidateList; uint public totalTokens; uint public balanceTokens; uint public tokenPrice; // what is the voter ...
0
votes
0answers
17 views

truffle migrate --network ropsten issues

When i run truffle migrate --network ropsten i don't see the contract deployment but just Compiling your contracts... =========================== > Everything is up to date, there is nothing to ...
0
votes
1answer
34 views

Is it safe to have a locally running Ethereum node exposing personal RPC API? [duplicate]

I am developing a REST API currently running off a node.js server. The API allows ethereum account creation, making a transaction etc. The API interacts with a locally running ethereum node to ...
0
votes
1answer
261 views

web3 Uncaught TypeError: Cannot read property 'createBox' of undefined

i'm trying to create simple application by using solidity 5.0.0 , Truffle v5.0.0 and web3 web3@1.0.0-beta.34. but i've gotten Uncaught TypeError: Cannot read property 'createBox' of undefined. ...
1
vote
0answers
45 views

No contract code at give address

Its a bit of a long question... I am using Go to deploy a Smart Contract using the following code: client, err := ethclient.Dial("http://localhost:8545") if err != nil { errorhandler.HandleErr(...
1
vote
1answer
35 views

How does smart contract work in network

I have read a lot about smart contracts and also have seen lots of implementation tutorials. But there are some ambiguous points in it that I can’t investigate it completely. For example: Imagine we ...
0
votes
2answers
36 views

If I wanted to host a site that used the web3 api, would I need it to interact with the blockchain?

I want to host a site to interact with Web3 clients (MetaMask, etc.). I want my site to be able to send transactions, etc. to the clients through the Web3 API for educational purposes. I don't care ...
1
vote
1answer
18 views

I am trying to build a land registry of land titles on the blockchain, [closed]

Good Day. I am trying to build a land registry of land titles on the blockchain, with the intention of being able to sell such title to someone else. Therefore, the title eventually has to be ...
4
votes
1answer
229 views

AssertionError: error message must contain revert

I have tried a lot of research. I still somehow can't find and understand why this error occurs when im in private network. But if in 127.0.0.1:7545 which ganache, everything seems to be working, all ...
0
votes
1answer
33 views

Execution of sending transaction never ends [UPDATED]

I send a transaction with web3 1.0.0 from a script like: async function sending(deployed_contract) { await deployed_contract.methods.mymethod(1).send({from: account}) .on('...
0
votes
0answers
28 views

prompt for metamask unlock

Is there a way to automatically open metamask unlock prompt ? Since I am able to detect metamask is available, instead of redirecting user to unlock.html I would prefer to try automatically prompt ...
0
votes
0answers
29 views

address.replace is not a function

I'm not really sure why this web3 method is being called in my code and why it's not a function apparently. Can anyone help me understand what the issue is here? Unhandled Rejection (TypeError): ...
0
votes
1answer
17 views

Creating a new contract specifying a sender and value with factory pattern

I am using a factory pattern to deploy its children contracts here. The child contract has a constructor as followed: constructor ( string memory _potName, uint _duration, uint ...