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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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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 () ...
2
votes
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 ...
0
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1answer
37 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
30 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
81 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
72 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 ...
2
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0answers
70 views

How to implement percentage deposit function to smart contract

I need to implement on the deposit function when the ownerAddress is doing a deposit a 10% to be freeze in the smart contract and and if the ownerAddress want's to call the returnDeposit function by ...
2
votes
2answers
114 views

Metamask now longer interacts with PetShop Dapp

Since November the 4th - In order for MetaMask to interact with your webpage dapps, you need to implement the windows.ethereum.enable as part of your scripts I have run through the pet shop tutorial -...
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1answer
19 views

One general contract for all or spawn new one for each instance?

What be the advantages vs. disadvantages or running a general contract or spawning a new one for each instance. Let say, that I am providing a contract so people can create their own crowdfunding. ...
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2answers
92 views

Deploy multiple instances of same contract

I am developing a decentralised notary app, using truffle/web3/react. It need to deploy multiple instances of a same contract. I managed to deploy multiple instances of a contract, MyContract via a ...
0
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1answer
21 views

Which type of Projects/Apps are suitable/best to be developed in blockchain/dapp technology? [closed]

Which kind of Apps are best to be developed on the base of blockchain/dapp/web3 technology. Suggest me please as I am looking for an advice for an academic final year project.
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0answers
22 views

Our vendor created the IPFS and Ethereum platform to store the PDF documents. How do i use the same code in Desktop Application

I am a quiet layman in IPFS and Ethereum. Our vendor created the web application which stores the documents IN IPFS (Ethereum). Now, we do need to do the same in the desktop application also. ...
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1answer
30 views

Understand inter-operation between typical DApp and its underlying smart contracts

I am a newbie to Ethereum and start to study some typical implementations of commonly-used DApp. So basically for the popular dapp on this list (https://www.stateofthedapps.com/rankings/platform/...
0
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1answer
126 views

“The returned value is not a convertible string” (web3js & React front end)

Edit: to be clear, the getMessage() function works fine in remix. It just doesnt seem to work with my front end. I am trying to set up a front end for my contract but when trying to invoke a certain ...
1
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1answer
48 views

How do you implement a “Micropayment Channel” in a Dapp?

I've come acrossed an article, Signing and Verifying Messages in Ethereum, where it says that you can pay for other user's gas transactions but so far I haven't seen any implementation or tutorial on ...
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2answers
106 views

Saving contract address after deploying with Truffle

To automate my development cycle I want to save the addresses of deployed contracts so that my DApp can read this information and know where to find the contracts on my private block chain: for ...
3
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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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1answer
39 views

Deployed Smart contract methods are not updating the value when restart the geth instance.Why?

Started Geth using following command geth --identity "testpvtnode" --rpc --rpcport "8545" --rpccorsdomain "*" --datadir <pvtnetdatapath> --port "30303" --rpcapi db,eth,net,web3,personal --...
2
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2answers
284 views

Is web3 completely decentralized?

I think web3 is not completely decentralized or safe to use. Consider the following example: I have made a voting Dapp on Ethereum. Now my smart contract will be on the Ethereum blockchain and my ...
0
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1answer
258 views

web3.js token approve function show null / 0 in Metamask

EDIT The allowance is set, the issue is just that metamask detect no token name nor amount that is allowed. In my HTML/JS amount = parseInt(web3.toWei(amount, "ether" )); tokeninstance.approve(...
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2answers
99 views

How to import quorum 7 node accounts to metamask

I am new to quorum 7node example I have created a DApp I want to send transaction using metamask when I was using testrpc to connect with DApp i was able to see all 10 test accounts in metamask after ...
0
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1answer
143 views

Calling a “view” function using web3js

--- HEAVILY EDITED --- Solidity contract: pragma solidity ^0.4.24; contract PatientRecords { struct Patient { string ID; string weight; string height; string diseasehistory; ...
0
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1answer
49 views

copy etherdelta code [closed]

For a test project, I need to write the etherdelta's contract. but "function EtherDelta (address admin_, address feeAccount_, address accountLevelsAddr_, uint feeMake_, uint feeTake_, uint feeRebate_) ...
0
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2answers
32 views

Can i use a contract which is deployed

I just have a question in my mind. can I use the contracts which are already deployed so that I can use them without even myself have to deploy it again. For example, take SafeMath I think I would ...
3
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2answers
44 views

Dual blockchain

Could anybody please help me to understand how dual blockchains work? There are many Dapps which are built on dual blockchains, especially using the combination of Ethereum and Hyperledger. But I am ...
3
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0answers
45 views

ICO for a startup I am planning to build but have some questions [closed]

I am an software developer with over 11 years of experience in industry and has worked as a software developer for some of the leading firms in vacation rental space. I recently started playing around ...
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1answer
23 views

Is attaching a name to an Ethereum address a “faux pas?”

I'm currently working on a DApp right now, and I was curious if it's considered poor design to include a string with the user's name that is mapped to a particular address. A user who has access to ...
0
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1answer
75 views

Adding quotation marks to string before calling a function [closed]

Alright, so I'm not sure if I should be asking this here or HTML/JavaScript forums, so please do let me know if I am in the wrong place. I believe it belongs here as you all understand dApps and ...
1
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2answers
70 views

How to use fiat exchange rate oracle in DAPP?

my team is trying to develop a DAPP about fiat exchange rate. How to get the latest fiat exchange rate (USD/EURO etc.) accurately from external Oracles(Or are there better ways doing this)?
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2answers
251 views

How to decode data parameter under logs in transaction receipt?

I went through many questions but I couldn't get my answer. web3 version -- 0.20.6 According to documentation event's parameters which are not indexed store in data parameter under logs. I want to ...
2
votes
4answers
165 views

Get rid of Metamask sign confirmation dialog

I am using web3 for users to sign some random string from web application. I give user string, he/she signs it after Metamask dialog's "Sign" button. but there is a problem when i want user to sign ...
1
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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
858 views

getting error nonce too low , but nonce is proper stuck since one day

I am working with web3.js since sometime now , but now i am stuck with nonce too low error , the nonce is proper also i have checked private key and other addresses , they also seem to proper , ...
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2answers
176 views

How to sign a transaction automatically? [duplicate]

An api will call the smart contract function. It should sign the transaction on its own instead of human intervention. I think raw transaction can work here. Are there any other options? Any help is ...
2
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1answer
134 views

How to transfer eth to a solidity function from a Dapp

I am trying to build a Dapp which includes functionality to deposit funds to a contract and withdraw them. The functions look like this function fundContract() public payable { require (msg....
0
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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?
5
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2answers
668 views

Login system for DAPP without metamask

I'm building Dapp on Ethereum. Imagine I have companies to register in my dapp, I will provide them with their own smart contract and public and private key pair, which they will use to just unlock ...
2
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4answers
447 views

Login system for DAPP

I'm building Dapp on Ethereum. The main feature of this Dapp is Register/Login logic. I Don't want to use Metamask, but I want to make Login system like MyEtherWallet without any chrome extention. ...
2
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2answers
41 views

using Ethereum without any gas or coins usage for transactions

I am new to Ethereum. We are planning to use Ethereum for building an application where-in we don't want the users to buy and use Ether's. We want the user's to safely store and retrieve / share the ...
0
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1answer
50 views

How to evaluate effectiveness of a Dapp

I am developing a private ethereum-based DApp and writing an academic paper for a final year project. I'm trying to "blockchainify" an existing system that adopts a traditional client-server approach. ...
1
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1answer
192 views

How to access metamask accounts when using Infura Websockets

I am making a dApp where in for login purpose I access metamask account to which user is logged in. I also have a back end server that listens to events emitted by the smart contract that updates data ...
1
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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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0answers
331 views

web3.personal.newAccount() successfully created but not listed in ganache accounts.why?

I am using truffle framework for Dapp development and I am new in Blockchain.I used the command web3.personal.newAccount() to create a new account. But i cannot view this account when i take ...
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0answers
17 views

In windows, what do I type in powershell to connect my dApp to a liteserver? [closed]

In windows powershell, what do I type to connect metamask to a liteserver? >
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0answers
22 views

Is it possible to deploy Dapp on Etherium classic network and be listed in mist?

So as a small bisness entety can not pay 100k USD for app deployment, one wonders on is it possible to deploy Dapp not in the test net but in a more real ETC one?
1
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1answer
95 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 ...
1
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1answer
147 views

Storing Non-Transaction data on Private(or Public) Blockchain

I'm fairly new to blockchain technology and need some advice for my first application. I'm creating a dApp for Asset Tracking using a private ethereum blockchain network. I have already created the ...
0
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1answer
48 views

How to catch Out of Gas exception in Oraclize Callback and display error on dapp front end

I have a smart contract inside which I have used Oraclize to get current time stamp. On few occasions the Oraclize callback fails due to out of Gas exception. How can one catch this failure and ...
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1answer
30 views

Is it safe to have a locally running Ethereum node exposing personal RPC API?

I am developing a REST API currently running off a node.js server. The API allows ethereum account creation, making a transaction etc. The API interacts with a locally running ethereum node to ...
1
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1answer
31 views

How does smart contract work in network

I have read a lot about smart contracts and also have seen lots of implementation tutorials. But there are some ambiguous points in it that I can’t investigate it completely. For example: Imagine we ...