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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.

1
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1answer
39 views

Simple smart contracts to make a bet

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.) ...
0
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0answers
15 views

How to execute a smart contract only if there are some particular tokens?

i created an erc20 token and i'm trying to create a smart contract that stores some informations in a blockchain and at the same time send a bit of my tokens to a wallet. Is it possible to do? Have i ...
0
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0answers
14 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 ...
0
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1answer
18 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 ...
0
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1answer
11 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. ...
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0answers
13 views

React Native FlatList example code Error [closed]

App.js /** * Sample React Native App * https://github.com/facebook/react-native * * @format * @flow */ import React from "react"; import SearchableFlatList from "./src/SearchableList"; const ...
0
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1answer
34 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
vote
1answer
34 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 ...
0
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1answer
20 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, ...
0
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1answer
24 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
18 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) { ...
2
votes
1answer
53 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 ...
0
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1answer
19 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 ...
0
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1answer
30 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?
0
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1answer
65 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. these ...
1
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2answers
33 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, ...
-1
votes
1answer
55 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 ...
1
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0answers
9 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 ...
0
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1answer
41 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 ...
-1
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0answers
35 views

How to send API request in HTTPS to smart contract using nodeJS?

Please help me with nodeJS API request. I setup HTTPS server in app.js but still api sends the request in HTTP. How can I send a request to smart contract in HTTPS? Code: userCreationApiRoutes.post('...
1
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0answers
20 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 ...
1
vote
0answers
18 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 ...
0
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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
14 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()", "...
0
votes
2answers
66 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
votes
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 ...
1
vote
1answer
33 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
26 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 ...
1
vote
1answer
28 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 ...
0
votes
2answers
47 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 ...
1
vote
1answer
117 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 () ...
1
vote
1answer
80 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
votes
1answer
30 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 ...
0
votes
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('...
1
vote
2answers
59 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 ...
1
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0answers
57 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
votes
0answers
55 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
89 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 -...
1
vote
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. ...
0
votes
2answers
62 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
votes
1answer
20 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.
1
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0answers
18 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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votes
1answer
28 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
votes
1answer
109 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
vote
1answer
40 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 ...
1
vote
2answers
71 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 ...
2
votes
1answer
94 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 ...
1
vote
1answer
31 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
votes
2answers
275 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
votes
1answer
220 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(...