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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Issue in Dapp using Angular 11.1.0 and web3 1.3.4 and Rinkeby metamask, getting error on new Web3(window.web3.currentProvider)

I am trying to create DAPP using Angular 11.1.0. I am able to deploy the contract on Rinkeby test network successfully. But on Client side getting below error on loading Web3@1.3.4 js. Getting error: ...
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Why doesn't web3.js/metamask have a decrypt with private key function yet?

For smart-contracts and dApps it is in many cases important to put encrypted data on the blockchain, encrypted with the public key. I have been searching, but there doesn't seem to be a way to decrypt ...
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20 views

How to recognize if a website is a DApp?

A Launch App button often appears on the top-right corner of Ethereum-platform websites. Is this an indication that a link is a link to a DApp (decentralized application)? Are the following two ...
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Wondering about an etherscan transaction, did not receive swapped coin

May be a bit of an noobie question, as I am not super confident navigating etherscan at the moment. I used the Bitswap dex from within the Trust Wallet app and swapped RSR for USDC. On etherscan the ...
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19 views

How to use Trust Wallet instead of Metamask on mobile browser?

Most DApps makes use of meta mask to sign transactions. I want my dApp to Make use of trust wallet when its opened on a mobile browser. How do I do this
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29 views

How do large Ethereum dapps get iteratively developed?

There are some extremely large projects on the Ethereum blockchain, like Augur. These dapps aren't short 100-line smart contracts, and are not uploaded once to the blockchain and done. Question: how ...
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29 views

Uncaught (in promise) TypeError: work.methods.workCount is not a function

Describe the bug I am trying to call the public variable "workCount" from a smart contract using web3 Steps to reproduce: const work = new web3.eth.Contract(ABI,Address) const workCount = ...
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Issue in Integrating metamask to chrome browser in mobile

I am trying to create an DeFi app by integrating the MetaMask wallet. Desktop The DeFi app works fine with the MetaMask integration Mobile I have my MetaMask setup in my Android mobile. When I tried ...
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42 views

Is Ethereum a DAO?

I am currently reading the book Token Economy from Shermin Voshmgir, which I am finding a very comprehensive overview of the current state of the Web3. I am still very new to the topic though, so bare ...
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Invalid implicit conversion from rational_const 5 / 2 to uint256 requested

I have the following code snippet inside my contract: plans[1100] = Plan(7, 3); plans[1101] = Plan(7, 2.5); plans[1102] = Plan(15, 4); plans[1103] = Plan(30, 6); plans[1104] = Plan(30, 5); When I try ...
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How to check whether the keystore file has been tampered?

The format of the keystore is shown below. In the project, there is a requirement to save the keystore file from the front end to the back end. How can the back end check whether the keystore file has ...
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Detect Lock/Unlock actions in MetaMask

I want my dApp to detect Lock/Unlock actions in MetaMask, just like in: Remix=>"Deploy & Run transactions"=>"Injected Web3" ethereum.on('accountsChanged'... - is not ...
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23 views

Should dapp backend sign all transaction. What problems may occur?

I have a dapp that communicates with one contract address. I want users to submit data in the frontend and then the data will be transferred to backend, where an ethereum account will make and sign ...
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29 views

Resubmitting the same transaction

A common concern for dapps using public blockchains is to check that a submitted transaction was included in a block after some time. And, if not, try to resubmit the same transaction (I mean, using ...
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Is it possible to schedule a transaction to execute after a certain amount of time in ethereum? [duplicate]

Is it possible to schedule a transaction to execute after a certain amount of time in ethereum? For example, I have a dapp where after two weeks I want to call a getRefund function on the smart ...
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28 views

Contract of contracts

I am new to solidity :) and try to encapsulate array of contracts in one contract. Something like this: contract Item{ uint public blabla1; uint public blabla2; } contract Collection{ ...
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25 views

Decentralized social media apps

Facebook, Instagram and Onlyfans are all centralized social media platforms. You don't have full control over your content once shared, it becomes metaphysically subject to the company's rules and ...
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my smart contract is not responding and error saying web3 is not defined

<script> var myContract; async function CheckMetamaskConnection() { // Modern dapp browsers... if (window.ethereum) { window.web3 = new Web3(window.ethereum); try { ...
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IPFS not returning anything

const ipfsClient = require('ipfs-http-client') const ipfs = ipfsClient({ host: 'ipfs.infura.io', port: 5001, protocol: 'https' }) uploadAsset = (cost) => { console.log("Submitting file ...
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estimating gas costs for dapps

I am new to ethereum and I am trying to build something like a vault where you can withdraw and deposit assets, based on the dApps protocols you are using (e.g :- yEarn, aave). I know there will be ...
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Difference between Ethereum Web APIs and Ethereum API as a service

I am approaching ethereum for the first time and I am reading the documentation. Can anyone explain the difference between Ethereum Web APIs (BlockCypher) and The Ethereum API as a service (infura)? ...
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Error message: Cannot read property 'eth' of undefined

<script type="text/javascript"> async function loadWeb3() { if (window.ethereum) { window.web3 = new Web3(window.ethereum); window.ethereum.enable(); } }...
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error comparing numbers in smart contract (Big Number)

I am unable to understand when all do we need to convert numbers to bigNumbers for asserting to be equal. In some cases by mistake i missed to convert integer variables to bigNumber and they worked ...
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39 views

How to identify ether payments from an exchange?

I am building an application that accepts payments from its users. Nowadays, only users with a wallet can make withdraws to a smart contract address(mine). This is because each user has a single and ...
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Read Solidity smart contract private field

Let's suppose this smartcontract: contract Test1 { string private i_am_private; string public i_am_public; ... } Solidity's compiler is automatically generating a getter function for public ...
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Display the user object array in react app using drizzle

I have been trying to do a simple use case where we return all the user details please find my code myComponent.js <div className="section"> <h2>JurStatus</h2> ...
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Cannot find module 'fs-promise' Error when importing a smart contract instance

I get this error when I try to open a page in the DApp I'm developing. Error: Cannot find module 'fs-promise' Require stack: - /Users/eimanalwahhabi/Desktop/RecycleChain/node_modules/swarm-js/lib/api-...
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36 views

How to I initialise an array inside the contructor in solidity?

I'm using the remix IDE.I want to define the size of the array at the time constructor is called. Someone please help. This is what I tried : pragma solidity >=0.7.0 <0.8.0; contract Vote { ...
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dapp without test.js

We can test our smart contract in remix and can perform several workflow checks before putting the contract in the final sol file in the dapp project. This way we can ensure that everything is in ...
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Get a users/contracts pending transactions?

Get a users/contracts pending transactions? I'm trying to get a users/contracts pending transactions so that when the Dapp is refreshed (or a new window is opened), any 'Pending' UI elements can know ...
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42 views

using only html page for frontend with web3 or ethers.js

I was just wondering, since we are able to write js scripts inside html docs, would we be able to create a dapp with fully functional html front end for our smart contracts? Or would we need to use ...
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Ipfs.add not working v48.3.1

I have tried for await ipfs.files.add(this.state.buffer) I have tried ipfs.add(this.state.buffer, (error,result)=>{console.log('ipfsresult', result) I'm new to all this. Any help will be ...
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What is a better way to use whisper to implement a chat room?

I want to use whisper to implement a chat room in my dapp. I learned about whisper, if you want to realize the function of private chat, you need to know the public key of other people. For a user who ...
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48 views

how can I pass data to my smart contract?

I have a threshold and some data that must be passed to the smart contract. The smart contract uses this data to make decisions. I'm using web3js. how do I pass this data to the smart contract?
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42 views

Cannot sign data using eth_signTypedData_v3 in coinbase wallet but can in every other dapp wallet?

Signing data worked in trustwallet, metamask, opera wallet. But not in coinbase using walletlink. Using eth_signTypedData_v3 - when sent to coinbase wallet via walletlink the error Cannot read ...
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Ethereum resources to build a decentralized application [closed]

I was searching the dApp Decentralized application topic and many resources recommend Ethereum to build a dapp. What I plan to do is to build a decentralized mobile app with a distributed database. I ...
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48 views

Storing hash on blockchain (hash of image stored on ipfs)

I am creating a dapp using react to store image on ipfs and the corresponding hash on blockchain. The purpose of storing hash on blockchain is timestamping, proof of ownership wtc and i wish to ...
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Call Smartcontract

I am working on an assignment to make a dapp. I am now preparing to generate a website via html. The problem I run into is that the buyToken function is not being called correctly yet <!DOCTYPE ...
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63 views

Recover RPC URL in Metamask

Can an application retrieve what RPC URL is the user using in Metamask? Using the window.ethereum API I can recover the net_version and confirm that it is the expected one. But can I also retrieve the ...
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236 views

Best way to go about connecting multiple wallets to Dapp

What I want: A user to connect a wallet to my dapp (1 of 4 choices, say: Metamask, WalletConnect, Formatic and Portis). The flexibility to create a custom "wallet connect modal" (I've tried ...
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52 views

How can I determine which smart contract belongs to which vendor/app/etc. I am interacting with?

Rarible lists (on https://rarible.com/contracts.txt): RC721Sale Contract - 0x131aebbfe55bca0c9eaad4ea24d386c5c082dd58 ERC1155Sale Contract - 0x93f2a75d771628856f37f256da95e99ea28aafbe ERC721 Nonce ...
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45 views

Sales Transactions in Ethereum [closed]

I am creating a Dapp for ERC721 NFTs. To execute a sale of an NFT from one user to another on my smart contract, I am calling the _safeTransfer function of openzeppelin from within another external ...
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65 views

Smart contract ability to query a database

I'm having some concerns while developing smart contract. As I see that, Ethereum blockchain can be known as a distributed database, where transactions are stored as hashes in a block. A smart ...
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55 views

TypeError: value.forEach is not a function when calling a function

I am using Truffle to deploy a contract on Ganache and retrieve the contract in an express app. While I can get the contract instance and it can console.log a list of function object, the function ...
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How to get transaction Status and data regarding that transaction in web3js?

I have a Dapp where user can buy and send ERC20 token whose bussiness login written in Smart contract..Now when someone buy the token, how do I know in web3 that how much token they've bought and what ...
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87 views

Events not working in Trust wallet or Metamask

Recently, I've developed an Dapp using pure vanilla js and it's contract is currently deployed on etherscan.When someone buys a token, it should increment..Everything's working fine but in the trust ...
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44 views

how to use custom web3 provider for Dapp?

I used to use metamask for Dapp development..Everything works fine, but trust wallet(Dapp mobile browser) doesn't emit events comes of from contract..My Dapp is heavily rely on events..if they don't ...
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13 views

Neither Token name nor supply shown in etherscan, instead shown “() N/A”

Recently, I've created an ERC20 token on Etherscan and verify the source code but my token information such as token name and total supply not showing up..Instead it shows balance: 0 N/a and supply ...
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24 views

transact to Auction.placeBid errored: VM error: revert. revert The transaction has been reverted to the initial state

I signed up for a "introduction to Blockchain" course in my exchange semester in South Korea and I feel like it's not just an introduction because for half of the final grade we get we have ...
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Import error for openzeppelin

I have tried both pragma solidity ^0.5.0; import "openzeppelin/contracts/math/Math.sol"; pragma solidity ^0.5.0; import "@openzeppelin/contracts/math/Math.sol"; Getting an ...

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