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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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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
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 { ...
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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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2answers
45 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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2answers
33 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
73 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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0answers
49 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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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 ...
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1answer
158 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
46 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
44 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
25 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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2answers
27 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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64 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
25 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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2answers
66 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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1answer
144 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
40 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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0answers
51 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
42 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
30 views

Stress test DApps on rinkeby test network

Is there any way of stress testing a dapp? I developed dapp, now I want to see how much stress it can handle? I can't test it on Main Ethereum Network. At least I can do it on Rinkeby test Network. ...
0
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1answer
63 views

Solidity Vs JavaScript?

I'm currently in the process of writing a game however a question has popped up in my head. A while back I started writing my game in Solidity (i.e the characters, names, stats etc.) and I had ...
1
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1answer
221 views

how to upload file into ipfs from node js without uploading files into node js server [closed]

I need to upload multiple files into ipfs from node js. Flow: file(html,angularJS) --> node.js --> IPFS --> ipfs hash save into DB. I have sent a file from HTML(angularJS) and I got the ...
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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, ...
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1answer
104 views

How do you set an icon for Metamask “DApp Connect” popup prompt?

For example, here, how would someone get a logo to appear instead of the default "A" logo?
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0answers
72 views

Uncaught ReferenceError: TruffleContract is not defined (Truffle Pet Shop)

I'm writing my own application that follows a similar form to the Truffle Pet Shop. I have the following code in my app.js: initContracts: function(){ $.getJSON('Greeter.json', function(data) { ...
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1answer
57 views

Oraclize a restfullAPI using a specific number represented by the variable z

Hello I made a restfull API on my own (python file jsonify + localtunnel) on a localhost using a specific number (in this case 141) represented by the variable z. This variable should go into DevCoin ...
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1answer
24 views

Just in time conversion to ETH in dApp

Let's say I want to facilitate transactions between two parties, and if there is one user who gives payment information, such as their bank account in USD, I'd like to exchange that into ETH ...
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1answer
100 views

How are truffle artifacts different from ABI?

How are truffle artifacts different from ABI? Do Truffle artifacts include fields that are different from ABI that is generated using remix?
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1answer
259 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
83 views

Collecting ERC20 balances from multiple addresses?

I'm building a dApp that involves creating unique accounts for individual users for ERC20 deposits [I keep the addresses and private keys in a centralized database], for popular ERC20 tokens like BNB, ...
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1answer
60 views

I want to oraclize this smartcontract to get some output on a localhost. I am desperate what should i do?

pragma solidity ^0.4.17; import "installed_contracts/oraclize-api/contracts/usingOraclize.sol"; contract DevCoin is usingOraclize { mapping (address => uint256) public balances; event ...
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0answers
11 views

Can I expose a dapp via whisper ?

I have a question regarding the possibility and probably the steps to do in order to be able to export my App via the whisper protocol. how to do it and in which case it can be better than other ...
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1answer
103 views

How can we access private blockchain from another network?

I have private Ethereum network running on my local network with two sealer node and one bootnode. I have deployed the private blockchain and configured it using geth. Now I want to create another ...
2
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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 ...
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0answers
27 views

How to setup Dapp on Cpanel? [closed]

I have followed the truffle petshop tutorial and it runs in my local machine, I have a shared hosting account and i would like to upload and test this Dapp on my server to start to modify it. The ...
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1answer
18 views

time order when calling functions of smart contract

How can I check that the miner actually execute the right order of smart contracts function calls, if there is a necessity of orders?
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1answer
17 views

Error creating contracts on Ethereum wallet. Need help [duplicate]

I am trying to create an ERC20 token off of ethereum, but when I put the code in the editor in the ethereum wallet, I get a weird error. It says: "throw" is deprecated in favour of "revert()", "...
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2answers
102 views

Creating a simple DApp [closed]

I want to implement the "Decentrilized Gallery", and implement it to the blockchain(ethereum) and it's kinda will work like: Basic html page with a button in the middle to choose a picture from ...
0
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1answer
44 views

Social networking websites build in ethereum blockchain have instant block time while in the main ethereum network it ranges from 10-20 seconds why? [closed]

I'm new to blockchain actually and I have an idea of a social app and want to build it in blockchain because of complete transparency and privacy-friendly and so. But I feel that it might piss off ...
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1answer
56 views

How to update value on ethereum blockchain without metamask?

pragma solidity 0.4.24; contract UniToken{ string value="Hello"; function set(string x) public { value = x; } function get() public view returns (string) { return ...
2
votes
1answer
38 views

Truffle's npm run build doesn't give me any .html and .js files in /build directory [closed]

I successfully deployed my contract with the truffle console. Then I wrote my DApp with the files index.html and app.js in the /app folder. I attempted to build my codes for production by running the ...
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1answer
70 views

Ethers js adding provider

I have an app I am working on implementing ethers.js. There are two methods I am using to create a wallet: new ethers.Wallet(privateKey, provider); and new ethers.Wallet.createRandom(); With creating ...
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2answers
151 views

Can I use the blockchain as a web server?

Is it possible to use the blockchain as "web server"? Even if a web app stores all data per smart contracts on the blockchain I still need a central server to get the web app initially. Is there an ...
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1answer
428 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 () ...
2
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1answer
151 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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1answer
42 views

Is there a boilerplate dApp on Github which uses uPort, truffle and infura on the ropsten testnet?

I am developing a dApp using those technologies and facing difficult problems when trying to save information on Ropsten. I can't approve my transaction via uPort because the selected account balance ...
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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('...
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2answers
133 views

How To store data in ethereum network using truffle framework ?How to achieve the database layer in dapps?

I am creating a dapp which has to be a login authentication system and some datas has to be store in database. So I really cant' store all the datas in Solidity's variable or class object, it has to ...
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0answers
97 views

Questions with Building a dapp using Quorum [closed]

I am working on a project to build a dapp for a trust system using Quorum, which needs a permissioned blockchain for data privacy. Only the admin, beneficiary, caregivers, case manager and authorized ...