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.

Filter by
Sorted by
Tagged with
0
votes
0answers
170 views

Issues with metamask in my project

Please look at images: The first images is what i get when logged in to metamask and the second image is what i get when not logged in to metamask When im logged in to metamask i can buy sell ...
0
votes
1answer
49 views

dApp design and security question

I'm designing a dApp where users can submit work they've done (files) to ipfs/swarm. To get credit for the work they then reference the hash of the files when calling a smart contract. What are some ...
0
votes
2answers
49 views

validation of data integrity in block

I am learning ethreum dapps development and have developed some dapps. I was thinking about supply chain dapp which i think , is very good application of blockchain as it ensures all the history of a ...
0
votes
2answers
41 views

Blockchain Development [closed]

I want to build a blockchain network such that if one node updates, all the other linked nodes gets update too. Think of it as Centralized Hospital record in multiple cities, if any of the city pushes ...
0
votes
0answers
255 views

web3.exceptions.BadFunctionCallOutput: Could not decode contract function call getEvidence return data b'' for output_types ['string']

Solidity Code: function getEvidence(string memory _evidenceID) view public returns (string memory) { require(evidenceOwner[_evidenceID] == msg.sender); string memory evidenceHash = ...
1
vote
1answer
120 views

Contract not deploying with web3

I'm writing a web-based DApp with web3, and am trying to get my JavaScript to deploy a contract. I've set up the abi, contract, and bytecode as follows: const trade_abi = [ ... not shown: ABI copied ...
1
vote
1answer
162 views

What are the steps of deploying a smart contract to the blockchain?

Are the above steps correct for deploying a smart contract to the blockchain: A node creates a smart contract The smart contract is converted to byte code The node creates a block out of the byte ...
0
votes
2answers
35 views

How are Ethereum smart contracts deployed?

Im a little confused on how Smart contracts work on the Ethereum blockchain and with DApps. I'm confused with the structure of DApps using Ethereum smart contracts. Is just one contract created when ...
1
vote
0answers
29 views

How to allow mobile wallets to sign and access to my dapp

I'm building a dapp application on Ethereum using React & Web3js. As usual the dapp will get the injected provider from Window.web3 (MetaMask), perhaps. The problem that I'm facing now is how can ...
2
votes
3answers
2k views

MetaMask - RPC Error: Internal JSON-RPC error

I am getting this error when i trying to use metamask on my local for a simple transaction from one account(say A) to another (say B). code: -32603 data: {originalError: {…}} message: "Internal ...
2
votes
1answer
32 views

How can I create Ethereum wallet addresses that can be revoked after certain time? Is it possible to do that?

How can I create Ethereum wallet addresses that can be revoked after certain time? Is it possible to do that? I am trying to create temporary wallets for employees in a company for their company ...
0
votes
1answer
160 views

Getting Metamask Error Message into web3.js DApp after user rejects transaction

I'm building a simple HTML/JavaScript front-end to interact with a Smart Contract using web3.js and MetaMask. I have a function to call one of the methods in order to send a contribution to the Smart ...
0
votes
1answer
42 views

Why Should I use Ethereum in an Online-Election(Vote) System based on ZKP(Zero-Knowledge Proof)?

I am an undergraduate student studying Ethereum in South Korea. Currently, I am developing an online election system that can be applied. At first, I came up with this idea: The system has an ETC ...
0
votes
1answer
16 views

Is allocating a portion of tokens to the dapp creator after a crowdsale a bad business move? [closed]

Will this lessen the integrity of the dapp? Will people trust the company less?
0
votes
2answers
24 views

Why would outside investors invest in a ethereum dapp? [closed]

I saw today that outside investors put millions into the Minds social network. I thought dapps had no real way of making money? What are the investors actually investing in? -the website that wraps ...
0
votes
1answer
54 views

What layers of a Dapp can be written in a regular high level language vs a niche one like Solidity?

I just saw that the Minds social network (a ethereum dapp I believe) is written in PHP. Their codebase is huge and I'm having trouble finding where their Smart contracts are written/how they are ...
0
votes
0answers
52 views

Payable function not working properly

Hi everyone hope I will be clear enough with the explanation because I couldn't find a proper solution. I am just trying to checkout an item with my buy function but it seems like I am stuck.Here is ...
1
vote
3answers
822 views

Alternatives to Metamask

What are existing alternatives to metamask with that works online inside existing browsers, that don't require installing a browser extension? What are some of the tradeoffs between them?
3
votes
0answers
3k views

account unlock with HTTP access is forbidden [duplicate]

I am using in the geth console and there is a similar error. Do I add "--allow-insecure-unlock" when I "init a node"? personal.unlockAccount(eth.accounts1) Any suggestion would be helpful. Thank ...
0
votes
1answer
40 views

Why am I getting a Parse Error in my smart contract after the constructor?

I'm writing a token sale smart contract & my original error was my function had the same name as the contract and I changed it to a constructor because the contract cant have the same name as the ...
1
vote
1answer
194 views

Both web3.eth.accounts.create() and web3.eth.personal.newAccount() not working

I'm making a dApp on reactjs. I wanted to create a new account and have done it trying 2 methods this.web3.eth.personal.newAccount() this.web3.eth.accounts.create() I have attached the code below(...
1
vote
1answer
299 views

getAccounts in web3 js undefined

I am working on dapp with web3js 1.0.0.37-beta with reactjs. I got blank in web3.eth.getAccounts. Following is my code App.js import React, {Component} from 'react'; import '../node_modules/...
0
votes
1answer
108 views

How does drizzle know when contract state has updated and reflect that state in the store (when a value has been `cacheCall`ed)?

Basically could someone provide a more technical explanation of this? It says that it watches(subscribes to) for block headers and when comes in it "through the transactions looking to see if any of ...
1
vote
2answers
128 views

Why is a failed transaction included in the blockchain as a “failed transaction”

According to this highest upvoted answer, "but still include it in the blockchain as a "failed transaction"... What is meant by the term "gas"?
0
votes
1answer
28 views

Can i use a the msg.sender which is a address to call a function of the contract?

I am trying to mint a ERC721 token using openzeppilin/contracts. It was working correctly, but later had to change the design. So now i am forced to use the msg.sender who is the minter to call the ...
1
vote
2answers
59 views

Decentralized Time server to get time in Dapps? [closed]

So basically i want to ask that how can we programmatically get the accurate, exact and current time in a DApp, without relying on the system's time or a centralized time server ? Is there a ...
2
votes
0answers
130 views

Android Studio And Ethereum?

how i can connect android studio application with Ganache? i'm trying to build an application on android (that is my Front end) with a Smart contract (Back end) on my private Blockchain (Ganache). it'...
0
votes
1answer
67 views

Call approve function() doesn't work

myContractInstance.methods.approve('0x...', 300).call(function(error, approve){ if(error){console.log(error)}; if(approve){console.log("allowance for this address :"+ approve)}; ...
0
votes
1answer
43 views

Cannot fetch account details

const accounts = await web3.eth.getAccounts() //sets the state of the account as a part of the constructor. console.log(accounts[0]) Id used the above code to display the account information of ...
3
votes
0answers
28 views

Nonce question please [duplicate]

can I have the meaning of the word Nonce explained please the question is rejected .. you people really do not wish there to be normal understanding by normal every day members of the public
2
votes
2answers
55 views

Geographic location in Solidity

Does solidity have a way of fetching a persons geographic location(using something like msg.sender)? Im building a dApp for national elections, and would need to verify the geographic location before ...
0
votes
1answer
27 views

Should I convert Centeralised web app to Multichain because it is free to use and more secure compare to webapp?

I am Web app developer and exploring the blockchain technology from few months. I want to convert the live centralized WebApp to Decentralized Blockchain application. I know there is a high cost ...
0
votes
1answer
59 views

Can Dapps set cookies

Is it possible for a Dapp that uses the metamask/chrome to set up a browser cookie? or can a cookie set by another website like facebook, read some information or at least know that a dapp has been ...
0
votes
2answers
36 views

Is it possible to instantiate a deployed contract in js using contract address alone? without copying abi data?

Is it possible to instantiate a deployed contract in js(dapp) using contract address alone? without copying abi data?
0
votes
2answers
67 views

do users should be aware of smart contract of the dApp they are using?

So dApps are frontend + contract. Users interact with smart contracts via frontend. Do users i.e. people should be aware of how the contract is designed while using any dApp? are their any risks of ...
0
votes
1answer
61 views

How do dapps connect to blockchain network?

Once the simple blockchain web applications runs on the web browser it uses the metamask to connect to the blockchain network, when it comes to mobile applications how the application connects to ...
1
vote
1answer
391 views

can etherscan.io show local ganache transaction details?

I am purchasing tokens on my sample Dapp with ganache-cli account using metamask. Metamask shows the confirm message and deduct the ether from total balance but in token section it still not update ...
0
votes
1answer
33 views

How can i make payment application using the blockchain? [closed]

i want to make payment based application by scratch using blockchain, so where can i learn from scratch and what are the different component that i should learn to make an application or a website ...
0
votes
0answers
534 views

web3.eth.getAccounts() returns empty array

I'm trying to get accounts like that: window.web3.eth.getAccounts( (error, accounts) => { console.log(accounts, error) } ); but it keeps returning an empty array. I'm running Ganache and I can ...
1
vote
1answer
92 views

How to replace Metamask Pop-Up with my own UI

I was wondering if I can replace the Metamask pop-up with my own pop-up/user interface. Example: Currently on my dApp a user clicks "Buy Token" and a Metamask modal pops up and says the usual ...
1
vote
1answer
156 views

Implementing a state channel

I am trying to build a platform to play TicTacToe using DApps. The players invite others by placing a stake and then opponents accept it. The first turn is recorded on chain by calling a function in ...
2
votes
0answers
58 views

How shoud I properly initialize DApp and get account address?

I am writing DApp in react, and basically I want to initialize web3, unlock account, and display it. Having web3 in my package.json In the onload I've tried to go following: let Web3 = require('web3')...
0
votes
0answers
121 views

How to use the ipfs.get()?

I am new to IPFS. I added a file in IPFS and then, pinned it. Now, I am trying to retrieve the file. I am writing the code in React. Hence I used the following code: ipfs.get('/ipfs/...
1
vote
1answer
88 views

getWeb3ClientVersion() returns null

I'm trying to create an android Dapp by using the web3j library. I'm using connection to a local private Ethereum blockchain. When I'm trying to display the Client version it returns null. This is the ...
0
votes
1answer
78 views

How to print “string” from Solidity in React?

My smart contract function is : function sNName(uint z)public view returns(string memory) { return abc[xyz[z].name]; } Where abc represents a mapping (bytes32 => string) In my .js file, I ...
1
vote
3answers
817 views

comparing two addresses

I'am trying to create a modifier that allows certain accounts to execute functions. address[] authorized; function verify (address adrs) internal view returns (bool) { bool exist; ...
0
votes
3answers
387 views

How to call a smart contract function in a DAPP?

I am trying to make a DAPP. I followed this link - https://medium.com/@takleakshar/how-to-build-a-decentralized-full-stack-app-in-ethereum-and-react-42e63d45a208 This is how my 'Setup.js' looks. ...
0
votes
1answer
27 views

can't get struct in return

I am trying to execute unit tests for a solidity smart contract: I have: mapping (bytes16=>Device) public Device_Table struct Device { bytes16 UUID; bytes16 hardware_UUID; string ...
0
votes
1answer
192 views

How to connect a dapp on private ethereum network [closed]

I created a private ethereum network with 3 nodes kai i have also created a dapp. How i can connect my dapp with my private network? Thank you!
1
vote
0answers
45 views

How to filter MyEvent({ },{ }) to retrieve only the latest transaction in the array?

My code: instance.MyEvent({}, {fromBlock: 0, toBlock: 'latest'}).watch(function(error, event) { if (!error) { console.log(event); $('#events').html(event.transactionHash); } else { ...

1 2
3
4 5
15