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.

179 questions with no upvoted or accepted answers
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5
votes
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717 views

Verify the ownership of an ethereum account

I have built a web game where users can purchase virtual items for their avatar with tokens obtained during an ICO. What is the best solution for delivering the items to the correct web game user? I ...
4
votes
1answer
297 views

Truffle hangs forever with parity with PoA

I'm trying to create a private chain using parity (PoA) and truffle but when I do truffle migrate it hangs forever with the following output: > [ > { > "jsonrpc": "2.0", &...
4
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0answers
112 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 ...
3
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0answers
143 views

Evaluation of DApp (Smart Contract) storage concept with IPFS

i hope you can help me improve or validate my storage concept. I am glad for each suggestion. Since this is my first DApp, i might not consider all possible options for my problem. To understand the ...
3
votes
2answers
193 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 ...
3
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0answers
59 views

EVM Invalid JUMP when using webpack app

I am creating a frontend app based on Truffle + Webpack, following this tuto : http://truffleframework.com/tutorials/building-testing-frontend-app-truffle-3, and have no uderstanding of JavaScript at ...
3
votes
0answers
49 views

Casting Object to BigNumber in Meteor DAPPs

Web3 incorporates the BigNumber library in order to handle 256bit numbers. I'm finding this problematic in Meteor as most of Meteor's reactive storage schemes such as Session, ReactiveDict and ...
3
votes
0answers
537 views

Pyethapp Build error: No files/directories in ..pip-build-gpzcs1\leveldb\pip-egg-info (fr om PKG-INFO)

I'm new to ethereum & do not have any ethereum clients 'installed'. I'm trying to install pyethapp in a clean virtualenv following the github tutorial, but it produces the following error. ...
2
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0answers
112 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'...
2
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0answers
47 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')...
2
votes
1answer
246 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
1answer
30 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. ...
2
votes
0answers
1k 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 ...
2
votes
1answer
296 views

Calling function from another contract reverts

I've been developing a dApp that needs ERC721 tokens. I have three contracts, a base contract, the one to mint tokens and another one for auctions. The inheritance looks like Base > Token > Auctions. ...
2
votes
0answers
201 views

Decentralized File Storage on Ethereum white paper

I am reading white paper of Ethereum, and I am confused by this example of the Section. Decentralized File Storage, which is part of the Section. Applications: The key underpinning piece of such a ...
2
votes
1answer
253 views

Does it make sense to have a Node.js backend serving json to frontend for dapp?

Currently, the architecture I am looking at is that the smart contract (SC) sits on the ethereum network, but it is a complex and multilevel contract system. Just navigating through the tiers of the ...
2
votes
0answers
618 views

What is the best practice of a Dapp development mixed with Python/Django?

I've written and tested the Smart Contracts in Truffle, and now want to develop a front-end and a small back-end for my Dapp. So far, I preferred MVP frameworks, particularly Django. Therefore, what ...
2
votes
1answer
263 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 ?
2
votes
1answer
217 views

How do I get access to uPort from a mobile Browser

I've developed a simple DApp that uses uPort and it works fine on Desktop - where I can login through uPort with the QR Code. On a mobile browser (Anrdoid Chrome) I'm auto directed to uPort where it ...
2
votes
0answers
419 views

Send transaction with metamask and web3

I'm new to the topic but can I somehow sendTransaction via contract instance? What I'm missing here? I simply want to send some ether to contract. var abi =[ { "constant": true, "...
2
votes
2answers
139 views

Possible to search swarm or blockchain?

I'm getting my feet wet in this blockchain world and looking to build a dapp based on Ethereum for maintaining an inventory of products. About 400,000 items that can be updated, removed or added to by ...
2
votes
0answers
52 views

show specific information to specific users in meteor dapp

if a have a dapp with different users, and each user has his/her own profile page they can log in to. On this profile page, the user should be able to change/add his user information (name, age, etc) ...
2
votes
0answers
36 views

How to return form data from an EthElements.Modal.question?

I'm trying to process data from an EthElements.Modal.question, however no event is passed when OK is clicked and this just points to the model call data and not the Template content.
2
votes
0answers
64 views

Why does Mist doest show up anything for me running on testnet

I just see a blank screen when I open Mist Browser on ubuntu running on testnet. What is the issue ? I couldnt start in the first place. But after using --ignore-gpu-blacklist I could start, Then I ...
1
vote
1answer
15 views

Automate faucet Ether request to access Ethereum Testnet from a mobile DApp

I want to develop a mobile DApp to interact with a smart contract deployed in a testnet (free of charges). The mobile DApp is designated for public users. The DApp needs first to setup a local wallet ...
1
vote
0answers
11 views

vyper no mappings allowed when adding a function to initialize a struct that has a map inside

Version Information vyper Version (output of vyper --version): 0.1.0b17+commit.eaa6754 OS: Debian GNU/Linux 10 (buster) Python Version - 3.6.2 Environment (output of pip freeze): asttokens==2.0.3 ...
1
vote
2answers
52 views

Accessing database in solidity

I am developing a voting application using blockchain (ganache). So basically i am registering the candidates by a web form and storing the data in phpmyadmin database. Now i want to access this data ...
1
vote
0answers
15 views

webpack packing website and upload to ipfs but node_modules not found

After webpacking the website, I upload the dist folder to ipfs. The ethereum part is working fine, however no js files (except for app.js) and node modules can be found. But as you can see in the pics,...
1
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0answers
17 views

Retrieve block number from geth and display it on my webpage

I am running geth using this command: geth -testnet --syncmode light console and I am trying to retrieve the block number from geth and display it on my web app. In geth when I type: eth....
1
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0answers
36 views

Delegate transaction signature

What's the most efficient and trust-less way to sign a transaction through a middle-ware? Thanks for your help.
1
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0answers
33 views

Gas station network use cases

I'm trying to understand the purpose of EIP 1613. Related to this website says "No more Metamask". So it assumes that a user does not have direct access to his private key / wallet. It means the key ...
1
vote
1answer
82 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
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0answers
27 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 ...
1
vote
1answer
145 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
80 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 ...
1
vote
0answers
44 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
vote
1answer
148 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 ...
1
vote
0answers
198 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
2answers
69 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 ...
1
vote
1answer
77 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 ...
1
vote
0answers
30 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 ...
1
vote
0answers
21 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 ...
1
vote
1answer
21 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 { ...
1
vote
0answers
100 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...", ...
1
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0answers
41 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.
1
vote
1answer
177 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 --...
1
vote
2answers
897 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">&...
1
vote
0answers
211 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
vote
1answer
84 views

Ethereum with Rails

I am much familiar with Rails but new in the Ethereum. But base on my understanding, if I am going to build a Dapp. The web stack should not include the back-end system like Rails. But why there's so ...
1
vote
1answer
118 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 ...