Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

1
vote
1answer
54 views

Not sent by ETN via transfer

I'm trying to make a lottery. pragma solidity ^0.4.23; contract Lottery { struct Ticket { uint id; address name; uint winCount; } uint public winFirstPercent = 60; uint public ...
1
vote
1answer
52 views

How to get notify if transaction got failed, dropped, or successes [closed]

I am new in dapps world and I want to deduct balance/points when a user buys an item currently I am unable to update balance because sometimes transaction got failed, dropped, or successes after 30 ...
0
votes
0answers
32 views

Dapp design to handle delay in callback response from Oraclize

In my dapp design I am receiving few user inputs via a form and passing them to a smart contract. Inside the smart contract I am using Oraclize service to timestamp the user inputs. Its a known fact ...
0
votes
1answer
98 views

How do DApps that don't need their users to run Ethereum nodes or Metamask work?

For example, A website which will give the option to register an ethereum account. The user would hit the register button and the server, which I assume is running a node 24/7 and will generate an ...
1
vote
0answers
20 views

trading a secret message with some person only after money is paid

I want to build a DAPP where person A trades a message with person B for ether. Since the message is secret, person A encrypts the message by using public key of person B and stores the message in ...
1
vote
1answer
35 views

Smart Contract Balance = 0

Ok, I am pretty new to developing contracts, and I did so by using dAPP and truffle. But when adding it to the chain, it says there is no balance to the contract. How can I add tokens to be bought? ...
0
votes
2answers
113 views

Is ERC721 an appropriate standard for managing licenses?

In my example scenario, I have an e-commerce dApp where e-books are sold. I originally thought that I could represent licenses to access these books using non-fungible tokens (NFTs) through the ERC721 ...
1
vote
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 ...
0
votes
2answers
117 views

ERC721 Dapp not working, not showing token owner

So I am building a Dapp to interact with an ERC721 contract. So far I'm able to mint, transfer and check an address balance. I'm stuck with trying to show who owns which token( via their token id). ...
1
vote
1answer
50 views

Double voting unit test failing on Election dApp

I am working through DApp University's election dApp tutorial. I made unit tests for invalid candidate, and double voting. My double voting unit test is failing, saying: 1) Contract: Election ...
0
votes
2answers
134 views

One IDE for running a DApp

Is there one IDE that can be used to run a DApp ? I have the backend (solidity) and trying to build the front-end for it.(So the IDE should help me to build the front-end side as well as run the ...
0
votes
0answers
18 views

How to create periodical token minting with randomness?

The Problem: I need to create a contract that will automatically mint tokens with some kind of randomness. For example, mint up to 5 tokens every window of 30-50 blocks: block #100 - contract ...
0
votes
1answer
133 views

Is it possible to check a token transaction history for an account with web3js?

If I have an account that has sent and received specific tokens, say ExampleToken (EXT), can I use web3js to see a list of EXT transfers and receipts for my address (or any other address)? I am ...
0
votes
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" });
0
votes
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 ...
2
votes
3answers
815 views

Why would I use Metamask instead of only using Web3.js in the browser?

It is my understanding that Metamask brings a convenient way for the user to interact with DApps by storing their wallets and by providing an interface that gives the user control of what the DApp is ...
1
vote
2answers
644 views

MetaMask verification on a server with web3.personal.sign

How to verify MetaMask account holder is the real owner of the address? I recently saw this post and tried it immediately, unfortunately, I am not getting the right result from the server. I think it ...
1
vote
0answers
49 views

import packages in petdapp

I unboxed petdapp and done some editing where I need to import bcrypt-nodejs in app.js and used following steps. npm install bcrypt-nodejs --save npm install require --save app.js var bcrypt = ...
2
votes
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. ...
0
votes
1answer
29 views

Search Struct or Mapping with minimum gas

I am trying to create a proof of existence dapp using IPFS and Solidity and wish to implement a feature to add 'tags' (like we attach to question on stack overflow) to each file/document uploaded on ...
0
votes
1answer
45 views

Checking if Contract Withdrawal Is Allowed

I am trying to conceptualization how a specific kind of smart contract would be written. The contract would basically handle deposits and withdrawals of ETH or some sort of ERC20 token. The balances ...
0
votes
1answer
139 views

Solidity - Shuffle address[] Index

Hello World ! I'm trying to find a way to shuffle an array of addresses in Solidity ! Looking at Underscore / Lodash source code _.shuffle() points out a few things. _.shuffle([1, 2, 3, 4]); * // ...
0
votes
1answer
38 views

MetaMask transaction popup opens on another computer

We have two computers on the same local network with Static IP for internet. When Computer A calls a transaction through a DApp for an address X, Computer B Metamask is also getting triggered with the ...
1
vote
1answer
199 views

ERC 721 rental contract

I am trying to write a contract for renting cars . I have implemented the following addCar -> to add a new car to the lot rentCar -> trasfers te ownership of the car to the rentee,and creates a rent ...
0
votes
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 ...
0
votes
1answer
210 views

WEB3.JS How do I configure a payable function front end with the input (DAPP)

I am trying add the front end part of a payable function using web3.js (And just vanilla JavaScript, no other libraries). Here is the solidity function: function deposit() public payable { ...
1
vote
1answer
107 views

What is the performance of dapps?

I understand that dapps are executed on the EVM and that the hardware requirements for Ethereum are low (aside from hardware space). However, I do not understand what the overall performance of dapps ...
1
vote
2answers
306 views

How to create a multiple contract with multiple instance

I would like to know how to create (via another contract or something else) several instances of the same contract with different parameters. For example create several different ERC20 on demand with ...
0
votes
0answers
58 views

Can't deploy token to private network

I tried to implement a token from this page But when he tries to send it from the account, throws a error. Contract code: pragma solidity ^0.4.24; library SafeMath { function add(uint a, uint ...
1
vote
0answers
22 views

Augur Project compile and debug

I starting to work on blockchain and dapps, would like to help with issues in augur can anyone explain how to debug or test run the application on my local machine to know how it works? i tried to use ...
1
vote
1answer
214 views

Is it possible to send ERC20 tokens to a smart contract that is written to accept payments..?

I have ERC20 compatible token that is already deployed in the ethereum main-net. I have a requirement to accept these tokens as payment, And this is going to be a new contract, The below are my doubts....
0
votes
0answers
137 views

web3 metamask, synchronous or asynchronous

Hello I developed a dapp browser using the metamask provider repo https://github.com/MetaMask/provider-engine However when loading some notable dapps (that work with the metamask chrome extension) ...
0
votes
1answer
40 views

How to modify my own ethereum node to mine transactions from my DAPP which uses ERC20 tokens?

Could someone please explain the below, I am developing a DAPP which uses ERC20 tokens that already deployed in the mainnet. In order to mine the transactions for these ERC20 tokens, How I can use ...
0
votes
1answer
348 views

Thoughts about implementing masternodes in a ERC20 Token

I am developing a cryptocurrency on top of ethereum blockchain that will have some sort of rewarding features for the large hodlers of the coin. I know two ways of doing that: Airdrop - like Pundi X ...
1
vote
0answers
155 views

Paying for gas on behalf of users?

I'm exploring ways to enable contracts/dApp owners to pay for gas on behalf of users. I know contact abstraction should enable this eventually, and the first step has been done with EIP208 which ...
0
votes
1answer
24 views

Issues with transaction signing

I have a desktop app that accepts payment from user in ETH and provides it some service for a certain amount of time depending on the amount. For that the user needs to sign the transaction in the ...
0
votes
1answer
49 views

Calculating a minimum entry fee for a game based on typical minimum gas requirements?

I am creating a dApp that is a game where players compete for the prize pool and that pool is built from the sum of all the entry fees payed by the player at the start of the game. The player that ...
0
votes
2answers
81 views

Decentralized dapp music player using smart contracts on ethereum?

Has anyone made a decentralized music player on ethereum using smart contracts? Say if I wanted to upload a mp3 file to IFPS and everytime someone plays the midi file the smart contract will deduct ....
0
votes
1answer
56 views

Which one is a better option - web3js or golang apis? [closed]

I want to build an application where I can call methods from smart contracts. I can do so by using either web3js or golang apis. Query: Which one is a better option when interacting with smart ...
0
votes
1answer
53 views

How to name the arguments in mapping?

In a regular solidity function, we have to name the arguments like: function getAddr(string AddrName) public. . . Here's the argument is a string which is named AddrName. I had build a dapp which ...
0
votes
1answer
192 views

What are the current challenges developers face in creating a dapp in ethereum? [closed]

Can you tell what are the pain points for the Blockchain developers while developing DApp/ managing consortium networks.
2
votes
2answers
52 views

Will Ethereum be able to support apps like Whatsapp?

Two sources: If Cryptokitties could take so much computing power in Ethereum network, how can the network support dapps with scale?, and; ONO White Paper: Chapter 3 Technical Framework In the first ...
2
votes
1answer
29 views

If Cryptokitties could take so much computing power in Ethereum network, how can the network support dapps with scale?

There has been so much hype about developing dapps on Ethereum. However, even transactions of cryptokitties could clog the network, how could Ethereum network ever support some application like ...
0
votes
0answers
5 views

Smart contract events only allowed inside <Rspan> tag?

I'm trying to use the oo7-parity library to make a dapp. But I only have access to the events emmited by the smart contract inside the Rspan tag privided by oo7-react. Isn't there a way of calling the ...
0
votes
1answer
157 views

Beginner - Design pattern for a hybrid dapp

This is the first dapp I'm going to build and I was thinking about not doing it 100% decentralized due to some limitations I've been encountering with Solidity (This may just be because of the way I'm ...
1
vote
2answers
192 views

How do we achieve immutability within a contract on the blockchain?

Am relatively new to the realm of Dapps and blockchain in general, and if you ask someone well-informed about the characteristics of blockchains, the word "immutable" will invariably appear in the ...
1
vote
0answers
23 views

The D in the DApp? Decentralised vs Distributed [duplicate]

Understand that the D in the DApp is decentralised. I saw some whitepapers put the D as distributed such as the flight chain whitepaper. What is the precise difference between decentralised and ...
3
votes
0answers
86 views

Evaluation of DApp (Smart Contract) storage concept with IPFS

i hope you can help me improve or validate my storage concept. I am glad for each suggestion. Since this is my first DApp, i might not consider all possible options for my problem. To understand the ...
1
vote
0answers
46 views

Can the unitsOneEthCanBuy value be changed after Token creation? [closed]

How can I change the value of "unitsOneEthCanBuy" in the contract ? (As the Token is only created & ICO has n't happened)
0
votes
1answer
561 views

How to access web3Instance when using Truffle's Drizzle

I'm working on a dapp with the boilerplate created by running truffle unbox drizzle and need to call functions provided by the web3 instance. Is there a way to access the web3 instance object? All we ...