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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.

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sent eth ropsten eth [on hold]

I sent eth(NETWORK ETH) ON the eth ropsten wallet address (BUT NETWORK ETH (myetherwallet.com)NOT ropsten eth). How to transfer to the wallet Eht ? TELL MONEY LOST OR CAN BE SEND BACK?
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1answer
6 views

Ethereum with Rails

I am much familiar with Rails but new in the Ethereum. But base on my understanding, if I am going to build a Dapp. The web stack should not include the back-end system like Rails. But why there's so ...
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1answer
34 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 ...
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34 views

Problem with Dapp in the browser

I'm trying to develop a voting Dapp, I have already created the Smart Contract and the js and html files. I have successfully migrated the contract into the Blockchain (I'm using Ganache), but when I ...
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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 ...
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1answer
96 views

Infura API for mobile(ionic) app

I have one little question. Suppose I have private key of user in ionic app. Is this enough to make transactions using infura API and web3?
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19 views

CORS policy error while connect to test-rpc

I'm trying to build my first dapp using test-rpc and web3js. I deployed a smart contract (with remix ide) to the testrpc (on linux ubuntu), when executing the following line: web3 = new Web3(new Web3....
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2answers
27 views

Returning all struct data of msg.sender in solidity

here is my code: contract Notes { struct notes { string id; string content; address owner; bool isCreated; bool isDeleted; uint256 timestamp; } ...
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1answer
41 views

Remix IDE getting VM error invalid opcode

I am attempting to deploy a test contract on javascriptVM using Remix IDE in chrome. However when I try to execute the contract I receive this message in the status section. "transact to Notes....
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2answers
78 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 ...
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1answer
75 views

Serving DApp on webserver or IPFS won't work

I can succesfully run the webpack truffle box on my webserver, but if I try to run a DApp which I made by using the pet-shop truffle box as template, I can only use it on localhost. When I upload the /...
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transaction not processing

The code below is for selling tokens to the smart contract, the INR_ETH.sellTokens() function calls the smart contract. but the code is not working properly, metamask asks for the "approve" part but ...
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1answer
22 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 { ...
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1answer
149 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. ...
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2answers
327 views

Solidity event listener

This web3js event listener is part of a Voting Dapp. The listener listens for a transactions and re-renders the page to show updates. listenForEvents: function() { App.contracts.Election.deployed()....
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1answer
94 views

Solidity cross programming language method calling

I was wondering if it is possible for solidity to call functions of other languages. More specifically, I am planning on developing a basic distributed search engine using the ethereum blockchain and ...
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2answers
38 views

Set and Get of a large amount of data

I created a contract that insert one number (uint) in blockchain with set function but how can i retrieve all numbers inserted? This is my html, i put 1 number in a blockchain and i will see just the ...
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1answer
109 views

How to connect Quorum with Metamask?

I'm trying to deploy smart contract on Private blockchain(quorum). And run the dapp on private blockchain. But I'm unable to connect the metamask with quorum network. The quorum is currently running ...
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3answers
1k views

calling smart contract functions from app.js

I deployed a smart contract to ganache network using truffle from account1. The code of smart contract is as follows. pragma solidity ^0.4.0; import "./strings.sol"; import "./safemath.sol"; ...
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2answers
103 views

Possible to search swarm or blockchain?

I'm getting my feet wet in this blockchain world and looking to build a dapp based on Ethereum for maintaining an inventory of products. About 400,000 items that can be updated, removed or added to by ...
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1answer
7 views

Function inside constructor is called from which address?

interface token { function transferFrom(address _from, address _to, uint256 _value) external returns (bool success);} contract CampaignFactory{ token public token_instance; constructor()...
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1answer
142 views

Why no dapps in the Google Play Store? Why Ethereum not accessible by default in smartphone?

Before I create a decentralized application, I want to know whether it already exists. I thought the first step would be to search the Google Play Store, but it appears dapps are not available on the ...
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1answer
19 views

Remix error: “Expected token LBrace got 'View' function get() public view returns (uint)”

I have this error during the compiling of the code below on Remix. Someone could help me ? pragma solidity 0.4.4; contract SimpleStorage{ uint storeddata; function set(uint x) ...
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1answer
352 views

Input data on Solidity

I'm trying to do something simple like Hello World that shows on a webpage. I've written a smart contract like this: pragma solidity ^0.4.18; contract HelloContract { string word = "Hello World!"...
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1answer
23 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 ...
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2answers
392 views

List ERC721 tokens owned by a user on a web page

Let's say that I have an ERC721 (NFT) contract that represents a set of playing cards. Is there sample code out there that shows listing all of the tokens of that ERC721 contract that a user owns on ...
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2answers
28 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
29 views

Storing User data on blockchain

I am currently using the structure and mapping to store the user data in the blockchain. In the mapping I am using user's address (msg.sender) for mapping it with structure so every user can only ...
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1answer
21 views

Getting error on sending ether/wei in payable function

error: transact to CampaignFactory.createCampaign errored: VM error: revert. revert The transaction has been reverted to the initial state. Note: The constructor should be payable if you send value. ...
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0answers
10 views

What is the difference in definition between both DApp and web-applicaion

Can I define a DApp as a web-app ? since a web-app is any computer program that performs a specific function by using a web browser as its client. What is the difference in definition between both ...
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2answers
21 views

How to use function arguments of payable function for require statement?

function createCampaign(uint deposit, address ll) public payable{ dpst = deposit; require(msg.value > (40*dpst)/100 wei); address newCampaign = address((new Campaign).value(msg.value)(...
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1answer
127 views

Can i delete some old files inside chaindata folder?

I am running geth with fast sync, Can i delete some old files inside chaindata folder so that my ssd will have some empty space or it will create some problems ?
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1answer
155 views

Which ethereum dapps are 100% decentralized and not semi-decentralized (centralized)?

Correct me if I'm wrong here, but I see dapps as independent solo code that you can download to you computer and it interacts with the Ethereum blockchain. Looking at crypto kitties, you have to ...
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45 views

Login to an ethereum dapp on sending a transaction?

I'm trying to build a sample dapp. The login process in ethereum dapps usually involves signing a message from metamask to prove ownership of an account. Is there a way we could design login in such a ...
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1answer
20 views

creating instance of contract trough a factory contract! Problems with balance!

hopefully someone can help me with my question. I have a factory to create an instance of a dealContract. Everything works except one thing. I cant send wei to the created instance, so lets see the ...
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3answers
3k views

How to generate Private key, public key and address

I can't find any documentation online about doing this in Javascript other than this. I want to know how does authentication work in a ethereum dApp's.. As per my understanding user seed somehow gets ...
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1answer
148 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 ...
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2answers
152 views

Mining, Ethers and Private Blockchain DAPPs

I am building a private Blockchain cluster DAPP envisaged to have 5 to 10 parties owning their own nodes (or node clusters). At this moment, there is no specific mandate to incentivize miners, though ...
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2answers
254 views

How to display blockchain transaction receipt details in an Ethereum Dapp

In my dapp design, I wish to provide the user with an option to view Blockchain Transaction Receipt Details either by a link to sites like Etherscan or by providing full details on a separate page in ...
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2answers
49 views

How to choose between Ethereum, EOS, and TRON if I want to build a dapp? [closed]

In 2018, Ethereum dapps has $2.6 Billion worth transaction volume in 2018; EOS has $3.45B; TRON has $600M. However, number of transactions on Ethereum is way less than EOS and TRON. Ethereum has a ...
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2answers
145 views

DAPP: is it possible to kind of “reset” data in contract?

I am just starting with all these dapp things and one thing is not completely clear for me. Ok, so I will just start from simple example. Let's say I want to create simple "Guess a number" dapp. The ...
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1answer
156 views

How do I get access to uPort from a mobile Browser

I've developed a simple DApp that uses uPort and it works fine on Desktop - where I can login through uPort with the QR Code. On a mobile browser (Anrdoid Chrome) I'm auto directed to uPort where it ...
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1answer
176 views

Calling function from another contract reverts

I've been developing a dApp that needs ERC721 tokens. I have three contracts, a base contract, the one to mint tokens and another one for auctions. The inheritance looks like Base > Token > Auctions. ...
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1answer
39 views

Execute smart contract only if the wallet contains some tokens [closed]

i created an erc20 token and i'm trying to create a smart contract that stores some informations in a blockchain just if the wallet contain my tokens. How can i do this? Have i to work on the token ...
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1answer
82 views

Simple smart contracts to make a bet [closed]

I would like to create a simple smart contract between me and a couple of friends (basically, I'm putting money on the line and betting them that I will do something that they don't think I'll do.) ...
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1answer
196 views

How to get only past 2 days events using getPastEvents everytime?

How can the following query be modified to only fetch the past two days worth of events: const events= await MyContract.getPastEvents("eventName", { fromBlock: 0, toBlock: "latest" });
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41 views

Sign a transaction locally and send it

I'm using Infura as my web3 provider, and have MetaMask installed to connect to the blockchain. I'm trying to send a transaction, but have learned that Infura is read-only, and doesn't support the ...
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1answer
243 views

Could not find artifacts for ./Election from any sources

I tried solutions provided in ethereum stack, but nothing worked for me. My smart contract file: pragma solidity ^0.4.15; contract Election { string public candidate; function Eletion () ...
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1answer
30 views

Design Dapp with Kotlin front end

To develop Dapp using Kotlin programming language for the front end design, Where should I place this code? and what it should be changed? <script> // Connect a the web3 provider ...
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1answer
167 views

How can I upload a smart contract to the Ethereum blockchain directly from a Raspbian Terminal without Parity, Geth, etc installed?

How can I upload a smart contract to the Ethereum blockchain directly from a Raspbian Terminal without Parity, Geth, etc installed? Hello, I primarily use a Raspberry Pi 3B with Raspbian OS ...