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.

2
votes
2answers
167 views

Mining, Ethers and Private Blockchain DAPPs

I am building a private Blockchain cluster DAPP envisaged to have 5 to 10 parties owning their own nodes (or node clusters). At this moment, there is no specific mandate to incentivize miners, though ...
0
votes
1answer
149 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 ...
0
votes
0answers
35 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 { ...
0
votes
1answer
25 views

How to connect a dapp on private ethereum network

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!
12
votes
2answers
4k views

Do users of ERC20 coins need to hold Ether?

Suppose there exists Fancycoin, an ERC20 altcoin which has some functionality implemented by the EVM. It does some nontrivial things that take up gas. According to my understanding, I can receive ...
1
vote
1answer
25 views

using a contract in another contract

I have my Callee contract in Callee.sol pragma solidity ^0.5.1; contract Callee { uint private val; constructor() public{ val = 30; } function getValue() public view returns(uint) { ...
1
vote
1answer
58 views

How to call a contract function that alters blockchain state on geth console

It should be easy, but I'm having a hard time using a simple smart contract described in the Solidity language reference called SimpleStorage. It only as one attribute, a setter and a getter, and I'm ...
0
votes
0answers
13 views

Can anyone explain how “The DAO” hacked? [duplicate]

Can anyone explain how "The DAO" hacked ? Is there any piece of code available(Where "The DAO" loophole ) in internet ? If available can please explain with that code where it("The DAO" - Smart ...
0
votes
1answer
19 views

What exactly happen when we execute truffle migrate --reset?

I have a old ABI generated by executing truffle migrate. Now I update the code and generate a new ABI by truffle migrate --reset. What exactly happens by executing truffle migrate --reset ? What ...
2
votes
4answers
870 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. ...
0
votes
1answer
93 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 ...
0
votes
1answer
87 views

Serving DApp on webserver or IPFS won't work

I can succesfully run the webpack truffle box on my webserver, but if I try to run a DApp which I made by using the pet-shop truffle box as template, I can only use it on localhost. When I upload the /...
1
vote
0answers
20 views

How to use web3-react with truffle Dapp? any sample code / tutorial?

I am new to react and finding issues with the front-end of the Dapp application. Especially in web3 version > web3 1.0.0 I just heard about the web3-react and I think it will be a lot easier. I ...
1
vote
1answer
30 views

where does the metamask fits in Dapps architecture?

i am learning building Dapps. And i got to know to know about metamask. I've read about metamask is an ethereum wallet which we can use to sign Tx's without running a full node and inject web3 to ...
0
votes
1answer
152 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?
0
votes
1answer
28 views

Can anyone explain How smart contract gets validated?

Is there any validation process of smart contract's write operations ?
0
votes
0answers
40 views

Timestamp is giving wrong time in smart contract

Today is June 17. but when I execute my function and store the following arguments. WriterModel(owner,postID, _postContent, now); "now", It returns the July 20 timestamp. It perfectly working fine ...
0
votes
0answers
21 views

Function returns always with the same input even it is in the loop..TRUFFLE+ANGULAR 7+WEB3

One of the function in Contract: function getPostCounts(uint _postID)public view returns(PostCountsModel memory postCounts){ return postCountOperations[_postID]; } This is the calling ...
0
votes
1answer
27 views

Value not pushing into array inside structure

pragma solidity ^0.5.0; contract Testing{ struct personalInfo { uint id; string[] colors; bool player; } mapping(uint=> ...
0
votes
0answers
31 views

Why this error occurring when i running my dapp?

I create a dapp using Solidity,Web3Js,Javascript and Html with metamask i always getting this error when i am trying to submit my transition i am getting this error at c (inpage.js:1) at ...
4
votes
0answers
107 views

Querystring in Parity Dapp frontend

I'm playing with local Dapp for Parity. When I'm trying to use query string in Dapp, I can't get it with js: I see that iframe is used inside, but have no idea, how to add query string there. Is ...
1
vote
2answers
225 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">&...
2
votes
1answer
127 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
vote
2answers
43 views

Storage/Retrieval of mapped structure data

I want to store the structure data in a mapping i.e. if I have a student structure as described below, then I should be able to have a myriad of students and distinguish between them using wallet ...
0
votes
0answers
22 views

Drizzle Installation: pauses at fetchMetadata: sill resolveWithNewModule http-https@1.0

I am following this tutorial https://www.trufflesuite.com/tutorials/getting-started-with-drizzle-and-react. Everything is working smoothly until I have to npm install drizzle. I then run into the ...
2
votes
0answers
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.
1
vote
0answers
10 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 ...
0
votes
0answers
33 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 ...
0
votes
1answer
24 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 ...
1
vote
1answer
212 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 ...
0
votes
0answers
42 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 ...
0
votes
1answer
33 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 ...
0
votes
3answers
1k views

calling smart contract functions from app.js

I deployed a smart contract to ganache network using truffle from account1. The code of smart contract is as follows. pragma solidity ^0.4.0; import "./strings.sol"; import "./safemath.sol"; ...
0
votes
1answer
38 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 ...
0
votes
1answer
453 views

Input data on Solidity

I'm trying to do something simple like Hello World that shows on a webpage. I've written a smart contract like this: pragma solidity ^0.4.18; contract HelloContract { string word = "Hello World!"...
0
votes
1answer
28 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.
0
votes
1answer
22 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 ...
0
votes
3answers
82 views

Ethereum Dapp Library [closed]

I would like to build Dapps on top of Ethereum and have a lot of ideas but the Solidity language is a bit difficult (at least to me). Is there a Windows library or a portable command line tool that ...
0
votes
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 ...
0
votes
1answer
38 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 ...
0
votes
1answer
77 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 ...
1
vote
2answers
160 views

DAPP: is it possible to kind of “reset” data in contract?

I am just starting with all these dapp things and one thing is not completely clear for me. Ok, so I will just start from simple example. Let's say I want to create simple "Guess a number" dapp. The ...
1
vote
2answers
177 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[]...
0
votes
2answers
27 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?
0
votes
0answers
22 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 ...
2
votes
1answer
178 views

Can i delete some old files inside chaindata folder?

I am running geth with fast sync, Can i delete some old files inside chaindata folder so that my ssd will have some empty space or it will create some problems ?
0
votes
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 ...
2
votes
1answer
199 views

Which ethereum dapps are 100% decentralized and not semi-decentralized (centralized)?

Correct me if I'm wrong here, but I see dapps as independent solo code that you can download to you computer and it interacts with the Ethereum blockchain. Looking at crypto kitties, you have to ...
1
vote
2answers
493 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
0answers
29 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?