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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25 views

Suck at JavaScript and overall just a beginner in the dev world. Whats the best way to begin building DApps? [closed]

Suck at JavaScript and overall just a beginner in the dev world. Whats the best way to begin building DApps? The title is my question LOL.
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13 views

DApp BPMN architecture design [closed]

I want to design my dApp on Ethereum but i want to explain the application logic (smart contracts) through BPMN to explicit my decentralized exchange.. Can someone help to design my decentralized ...
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91 views

Error: The data field must be HEX encoded data

I am trying to make a simple dApp by using a tutorial. I am using the following command ; npm install ganache-cli web3 so that we can use web3 to get fake ethereum nodes/accounts by connecting it ...
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75 views

Can't connect to localhost:8545 while using ethereumjs-testrpc web3?

I am developing a simple Voting dApp by following a tutorial. In this tutorial we are using npm install ethereumjs-testrpc web3 so that we can get the fake nodes of Ethereum. For that i first ...
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1answer
42 views

Asymmetric encryption with master Key

Is there any way i can derive private and public keypairs from a Master Key? The Master Key should be able to decrypt every encryption made with the generated Keypairs. to explain a bit further i ...
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2answers
29 views

condition check of struct mapping in solidity?

struct User { string username; string password; address userid; bool isAdmin; } mapping (uint => User) users; function checkIfUserExists(address userid) public ...
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1answer
48 views

how to securely share digital asset in a fully decentralized DApp

I want to design a proof of concept of a fully decentralized secure asset sharing DApp. Seller uploads the asset they want to share with a price and buyer pays it with ether or a token. Frontend and ...
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1answer
31 views

Are there any smart contract templates?

I'm looking for one or more possibly open source Ethereum smart contracts that have been tested and perform some useful use case.
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0answers
7 views

How often should the Web3.py provider connection be shared in a django project?

My django project directory structure is the following ... projectRoot projectName __init__.py settings.py urls.py wsgi.py App1 __init__.py admin.py models.py ...
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1answer
24 views

Easier Installation of privatenode for non-technical users

I have seen documentation of creating privatenet using geth. But it holds few commands which will not be a better option for users/clients who doesn't have technical knowledge to use the application ...
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1answer
52 views

How to create a local account from an external private key in Web3.py?

I've been using local_account = w3.eth.account.create(keys['private_key_1']) to create a local account offline. When I check the public key returned from local_account.address it does not match the ...
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1answer
103 views

Transfer all msg.sender.balance to contract, without requiring user to input the msg.value?

Is there a way to drain all the user.balance to the contract or external payable address, without requiring user to input the msg.value? The most intuitive version I had looks a bit like this on ...
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23 views

Monetizing my dApp

I'm working on a project that will allow users to use our platform to auction stuff. Programatically, how would I convert this idea into a profit for me. I want to take a 3.75% fee from any won ...
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2answers
52 views

How do I send NFT assets (ERC721 Tokens) from my Ethereum wallet to someone else?

I want to send my ERC-721 to my friend. Fast. Any suggestions?
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0answers
11 views

Creating DApps over existing crypto

Can I create DApps over existing crypto in the network, if yes then please help me with some like or description of the process to create such DApps if anyone can point me some blog then it will be ...
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0answers
32 views

Can value of a public variable in Solidity be called and returned by web3?

How to get value of a public variable in Solidity be called and returned by web3?
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12 views

How to console.log the value in the React js for the Dapp + truffle project

I am beginner with the ReactJS and Dapp. In my js page I want to get the value after doing some operation on the input value and want to dispay that result. I got the Nan in the front-end screen. ...
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21 views

Is it safe for Ethereum Alarm Clock or Aion?

Scheduling service of EAC and Aion depend on participating users. Q1) is it safe for private keys of users? Would not it be possible to track the execution of the transaction and rob the private key?...
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1answer
67 views

truffle unbox react - front end is unable to read / set state of the contract

I am experiencing problems with the Truffle React boilerplate code that the front end is unable to read / set state of the contract. Here are the details: I unboxed the React boilerplate using ...
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0answers
13 views

Why does Dapp need npm?

I found a lot of tutorials say anyone who creates dapps needs to use Node Package Manager (NPM). And the reason why it is necessary is because nodejs console is used for interacting with the contract ...
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1answer
23 views

How does Ethereum ensure that “users can own their data, and your apps don’t spy and steal from you”? [closed]

What features in ehtereum would ensure that the Dapp would never spy on you or steal your data?
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1answer
47 views

How to automatically pre generate thousands of ETH addresses for my app users

I'm building an app where every user will have app-generated ETH Wallet to do transactions with internal ERC20 Tokens. I would like to pre-generate wallets for my users, and assign every wallet upon ...
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0answers
28 views

Transaction included in block whereas log not generated

When I sent a transaction continuously below 27 Transaction Per Second (TPS) then all transaction is included in a block and generated the log as expected. Whereas When TPS increases above 27 then ...
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0answers
19 views

Transaction sent from web3 cannot reached all transaction to network node

I used one node endpoint to interact with the network. While sending a transaction from web3.js 0.20 to ethereum network, transaction per second (TPS) I achieved is only 28 TPS. I have configured the ...
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1answer
196 views

Empty value (0x) returned from contract web3j

I'm trying to deploy a very simple contract on Windows 10, using Web3j 4.2.0. I've created an account using Mist. I've set up one local ethereum node (using geth) on my machine and I'm able to deploy ...
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1answer
14 views

can I return an address from a contract interface instead of another contract?

for example i have a contract function that returns a contract, can I define an interface that calls that function, but only returns an address? contract foo { .... .... } contract bar { ...
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1answer
34 views

Ethereum Game design idea

Is it possible to write emacs dunnet game in solidity? Not that there is any reason for the game to be on a blockchain, it is for a class assignment. I tried 2048 game. But it seems to have some ...
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3answers
308 views

How much does it cost to develop and run dApp on Ethereum or Hyperledger fabric?

When we develop and run a non-decentralized application it causes costs for using cloud server. How much does it cost to develop and run dApp on Ethereum or Hyperledger fabric? Which one is cheaper?
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0answers
82 views

sendTransaction never resolves on web3.js 1.0.0 beta49 - beta52

My plain vanilla sendTransaction doesn't ever resolve on ganache with web3js 1.0.0 beta52: async function sendTx() { const receipt = await web3.eth .sendTransaction({ to: "0x1...", ...
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2answers
388 views

How can I return dynamic string array in Solidity?

How can I return a dynamic string array? I came across serialization and deserialization. How can I serialize and deserialize dynamic string array ? pragma solidity ^0.5.0; contract Abc{ string[]...
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24 views

IPFS - file stored by all users

Suppose one or many users used my fully decentralized app to store different files on IPFS. How can I keep track of all file hashes by using smart contracts?
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1answer
33 views

Fully Decentralized Dapp [duplicate]

How can I build a fully decentralized dapp where the frontend code (.html,.css,.js) and ABI files (build/contracts/json) are stored in ipfs and contracts on test-network. But I am unable to do so ...
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0answers
40 views

NuCypher for storing file securely on IPFS

Please someone guide me how I can use NuCypher Algo for storing a file on IPFS such that only a set of people can open its ipfs-hash link. Can you tell the implementation because I am finding it ...
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0answers
27 views

Smart Contract ABI in Remix (Ethereum)

When I deploy smart contract on the Rinkeby network using Remix the ABI of smart contract does not contain its address, so how do I connect it with my frontend application.
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1answer
12 views

Corporate key store for storing private keys - Ethereum

Is there a device to store private keys of Ethereum in a corporate world? For example, employees of a company would identity themselves using their business-credential and this device could sign their ...
0
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1answer
55 views

Truffle contract.deployed does not get the latest instance deployed

I am developing a back-end DApp using truffle and nodejs on a private network. My application call Contract.deployed() and print the address of the obtained Contract. When I call truffle migrate --...
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0answers
9 views

Instance of sol file in browser

How do I get the instance of sol in browser using js. In React it happens like: import SimpleStorageContract from '../build/contracts/SimpleStorage.json' const simpleStorage = contract(...
1
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2answers
306 views

Uploading files on IPFS Infura

I am trying to make a dapp to upload files on IPFS Infura. I am using IpfsHttpClient in web browser by including the script <script src="https://unpkg.com/ipfs-http-client/dist/index.min.js">&...
3
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1answer
337 views

Infinite loop in a view

How is ethereum network protected against infinite loops in views? In normal transaction you have to pay a gass, so it would be too expensive for you, but calls to views are for free. For example ...
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0answers
64 views

IPFS dapp hosting

I have uploaded the dapp frontend folder along with contracts json files on the IPFS using ipfs add <path> ipfs name publish <hash> commands. I am running Ganache for in-memory virtual ...
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1answer
135 views

truffle migrate --network ropsten issues

When i run truffle migrate --network ropsten i don't see the contract deployment but just Compiling your contracts... =========================== > Everything is up to date, there is nothing to ...
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1answer
101 views

Dapp on Ganache and Truffle but… what about Remix?

My dapp runs well with Ganache and Truffle but how to deploy with Remix and connect the contract to web GUI without abi? I mean, i created a Dapp that runs really good on Ganache and i run the web ...
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0answers
81 views

No contract code at give address

Its a bit of a long question... I am using Go to deploy a Smart Contract using the following code: client, err := ethclient.Dial("http://localhost:8545") if err != nil { errorhandler.HandleErr(...
1
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1answer
34 views

I am trying to build a land registry of land titles on the blockchain, [closed]

Good Day. I am trying to build a land registry of land titles on the blockchain, with the intention of being able to sell such title to someone else. Therefore, the title eventually has to be ...
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0answers
164 views

prompt for metamask unlock

Is there a way to automatically open metamask unlock prompt ? Since I am able to detect metamask is available, instead of redirecting user to unlock.html I would prefer to try automatically prompt ...
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0answers
73 views

address.replace is not a function

I'm not really sure why this web3 method is being called in my code and why it's not a function apparently. Can anyone help me understand what the issue is here? Unhandled Rejection (TypeError): ...
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1answer
27 views

Creating a new contract specifying a sender and value with factory pattern

I am using a factory pattern to deploy its children contracts here. The child contract has a constructor as followed: constructor ( string memory _potName, uint _duration, uint ...
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1answer
24 views

Website to generate Ethereum Hash of a PDF file

I would like to ask a user to generate a "Keccak-256" or "Keccak-512" (Ethereum versions of SHA3) of a PDF file. Is there a recommended website with a good GUI to generate that? The user would input ...
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1answer
65 views

How to create and manage a referral link on solidity Smart Contract (unique referral link)

I'm building a DApp in solidity where I want give a bonus to the users that wants promote it. My problem is that, to use my Referral system, now I need to insert manually the wallet address of the ...
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1answer
27 views

Blockchain Hark Fork System Impact - risk assessment and mitigation plan

I am exploring on System Impact risk assessment and mitigation plan during a block chain (ex –Ethereum) hard fork. 1) What happens to the deployed smart contracts when a hard fork occurs? 2) Does ...