Trending questions in Blockchain

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How to get value from solidity contract using java?

web3j caters for this very use case. It ...READ MORE

Sep 28, 2018 in Blockchain by slayer
 • 29,370 points • 2,688 views
0 votes
1 answer

Are Ethereum contract function securable?

The reason is that you are using ...READ MORE

Oct 30, 2018 in Blockchain by Christine
 • 15,750 points • 1,397 views
0 votes
1 answer

Hyperledger Fabric: build error "files are missing SPDX-License-Identifier headers"

Try this: make peer orderer peer-docker orderer-docker tools-docker ...READ MORE

Oct 30, 2018 in Blockchain by Omkar
 • 69,180 points • 1,299 views
0 votes
1 answer

Web-scraping from Coinbase with Python (Pycharm)

Data that you want to scrape is ...READ MORE

Sep 4, 2018 in Blockchain by digger
 • 26,740 points • 3,719 views
0 votes
1 answer

HyperledgerFabric : *SampleChaincode does not implement shim.Chaincode error

The reason you are getting this error ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 1,339 views
0 votes
1 answer

Ethereum Mist: Compiling Error with sha3

First run: npm install sha3 and then sudo ...READ MORE

Oct 24, 2018 in Blockchain by Omkar
 • 69,180 points • 1,540 views
0 votes
1 answer

Not able to invoke a contract in Ethereum Private chain using geth

Hope this helps: contract mortal { /* ...READ MORE

Oct 22, 2018 in Blockchain by Omkar
 • 69,180 points • 1,625 views
0 votes
2 answers

Check Bitcoin Balance with mybitx api https GET url

You can use the PHP Requests library for an ...READ MORE

Sep 17, 2018 in Blockchain by Lalit
 • 3,195 views
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2 answers

Ethereum function completed not event not showing up

Oh ya. I was passing unit but ...READ MORE

Oct 24, 2018 in Blockchain by slayer
 • 29,370 points • 1,481 views
0 votes
1 answer

How to input realtime data from google sheets into urlfetch google scripts?

Based on your title I hope to ...READ MORE

Oct 12, 2018 in Blockchain by Perry
 • 17,100 points • 2,024 views
0 votes
1 answer

UnhandledPromiseRejectionWarning: Insufficient funds error in Ethereum: NodeJS web3

sendSignedTransaction returns a promiEvent onto which you can chain then and catch: web3.eth.sendSignedTransaction('0x' + ...READ MORE

Oct 15, 2018 in Blockchain by Omkar
 • 69,180 points • 1,905 views
0 votes
1 answer

Blockchain: Installing an earlier version of ethereum using apt-get on

geth does not make the previous version available ...READ MORE

Oct 10, 2018 in Blockchain by Omkar
 • 69,180 points • 2,099 views
0 votes
1 answer

Hyperledger Composer: How to save deployments?

You are losing your deployments probably because ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 1,276 views
0 votes
1 answer

Hyperledger Fabric: ./byfn.sh -m up failed

Try adding GODEBUG=netdns=go to the environment variables ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,395 views
0 votes
1 answer

How to install v1.7.3. of Geth using ppa?

The Ethereum PPA generally provides the latest ...READ MORE

Oct 17, 2018 in Blockchain by Christine
 • 15,750 points • 1,774 views
0 votes
2 answers

Web socket API session automatically disconnecting

Yes, the code given by Christine works! ...READ MORE

Aug 29, 2018 in Blockchain by digger
 • 26,740 points • 3,864 views
0 votes
1 answer

Ethereum Advance token sample

Using > instead of >= is a ...READ MORE

Nov 2, 2018 in Blockchain by Christine
 • 15,750 points • 1,052 views
0 votes
1 answer

Hyperledger Fabric : How to initialise a 2D array in .cto file?

You could try something like this, with ...READ MORE

Oct 30, 2018 in Blockchain by Omkar
 • 69,180 points • 1,185 views
0 votes
1 answer

Why do the resultant hash after mining has a leading no. of zeroes in Blockchain verification?

This is chosen by the DIFFICULTY EQUATION. In ...READ MORE

Aug 10, 2018 in Blockchain by Christine
 • 15,750 points • 4,664 views
0 votes
1 answer

Hyperledger Composer cant find business card.

I changed the code to: var businessNetwork = ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,330 views
0 votes
1 answer

Hyperledger Composer: Error trying to instantiate composer runtime.

It looks like a problem with composer-cli.  A ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,290 views
0 votes
1 answer

Are there null like thing in solidity

You could create none variable to use it as ...READ MORE

Sep 21, 2018 in Blockchain by digger
 • 26,740 points • 2,787 views
0 votes
1 answer

Bitcoin: parsing Blockchain API using JSON

Because you only add one address to ...READ MORE

Aug 22, 2018 in Blockchain by digger
 • 26,740 points • 4,069 views
0 votes
1 answer

Cant query in Hyperledger Composer

There's a mistake in your WHERE statement. ...READ MORE

Oct 26, 2018 in Blockchain by Omkar
 • 69,180 points • 1,259 views
0 votes
1 answer

Error when trying to deploy Ethereum smart contract using web3j

Create a new credential based on the Credentials.create ...READ MORE

Oct 3, 2018 in Blockchain by slayer
 • 29,370 points • 2,246 views
0 votes
1 answer

Integrating web3 in cloud functions module

I had this issue and my problem ...READ MORE

Oct 17, 2018 in Blockchain by Perry
 • 17,100 points • 1,634 views
0 votes
1 answer

Hyperledger fabric: vagrant up in devenv fails

This is a problem with vagrant 1.9.3: You ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 1,107 views
0 votes
1 answer

How to read the ETH value and other token values from an account?

You can do this eth.accounts shows you all known ...READ MORE

Oct 22, 2018 in Blockchain by Omkar
 • 69,180 points • 1,394 views
0 votes
1 answer

Unable to change a state variable in a contract

I am assuming that the issue is ...READ MORE

Oct 30, 2018 in Blockchain by Christine
 • 15,750 points • 1,063 views
0 votes
1 answer

Is the msg.sender address changed while passing to another contract as a parameter?

I tried your contracts in Remix, but ...READ MORE

Oct 10, 2018 in Blockchain by Omkar
 • 69,180 points • 1,898 views
0 votes
1 answer

re hyperledger's node/sdk: there is no typing definition( index.d.ts )

Looks like a bug in that the ...READ MORE

Oct 23, 2018 in Blockchain by Perry
 • 17,100 points • 1,319 views
0 votes
1 answer

Historical ethereum prices - Coinbase API

def get_spot_price(self, **params): """https://developers.coinbase.com/api/v2#get-spot-price""" ...READ MORE

Sep 21, 2018 in Blockchain by digger
 • 26,740 points • 2,692 views
0 votes
3 answers

UnhandledPromiseRejectionWarning: Error: The contract code couldn't be stored, please check your gas limit

I believe bytecode is being treated as ...READ MORE

Sep 24, 2018 in Blockchain by Teja
 • 2,473 views
0 votes
1 answer

How to efficiently hash (SHA 256) in golang data where only the last few bytes changes

You can try the following examples on ...READ MORE

Jun 27, 2018 in Blockchain by aryya
 • 7,460 points • 6,387 views
0 votes
1 answer

How to Query hdfs with Spark Sql

Yyou can achieve this by creating Dataframe. val ...READ MORE

Sep 20, 2018 in Blockchain by slayer
 • 29,370 points • 2,711 views
0 votes
2 answers

How to check if bitcoin address is valid?

For Java, have a look at the ...READ MORE

Aug 20, 2018 in Blockchain by Omkar
 • 69,180 points • 4,006 views
0 votes
1 answer

Test ethereum Event Logs with truffle

You are passing tx hash into done() ...READ MORE

Sep 21, 2018 in Blockchain by slayer
 • 29,370 points • 2,662 views
+1 vote
1 answer

Using bccsp instance from chaincode

You can take a look at this code snippet. ...READ MORE

Oct 22, 2018 in Blockchain by Christine
 • 15,750 points • 1,280 views
0 votes
1 answer

Nodejs cannot access Hyperledger composer shows error

1) you need Node 8.9.x or higher ...READ MORE

Oct 23, 2018 in Blockchain by Perry
 • 17,100 points • 1,254 views
0 votes
1 answer

Go ethereum: Gradle sync error

Try the below code : maven { ...READ MORE

Oct 24, 2018 in Blockchain by Omkar
 • 69,180 points • 1,202 views
0 votes
1 answer

Cant extract hyperledger artifacts

Simplify the PATH first. In a CMD, type: set PATH=C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\ set ...READ MORE

Oct 29, 2018 in Blockchain by Omkar
 • 69,180 points • 977 views
0 votes
1 answer

Docker on mac error message can't connect to Docker endpoint

While CORE_VM_ENDPOINT set to unix:///var/run/docker.sock, please make ...READ MORE

Sep 19, 2018 in Blockchain by slayer
 • 29,370 points • 2,680 views
0 votes
1 answer

How can I deploy a hyperledger business network using docker-compose?

If you want to use Composer, be ...READ MORE

Oct 4, 2018 in Blockchain by Perry
 • 17,100 points • 2,026 views
+1 vote
3 answers

Pass all .dat files in folder to function

os.listdir(path) return names, not fullpaths change parseBlockFile(file) to fullpath = os.path.join(path,file) if os.path.isfile(fullpath) ...READ MORE

Sep 5, 2018 in Blockchain by Saygum
 • 3,161 views
0 votes
1 answer

pubToAddress method from ethereumjs-util throws AssertionError: false == true

This code works fine: var keythereum = require('keythereum'); var ...READ MORE

Oct 8, 2018 in Blockchain by Omkar
 • 69,180 points • 1,825 views
0 votes
1 answer

How do I send ether from an EOA to a smart contract?

You include ether to send in the ...READ MORE

Sep 27, 2018 in Blockchain by digger
 • 26,740 points • 2,298 views
0 votes
1 answer

truffle migrate Error

testrpc Check your truffle.js config port and ip ...READ MORE

Oct 8, 2018 in Blockchain by Omkar
 • 69,180 points • 1,790 views
0 votes
1 answer

How to define the path to hyperledger-fabric chaincode?

You can find that in docker-compose files ...READ MORE

Oct 4, 2018 in Blockchain by Perry
 • 17,100 points • 1,955 views
0 votes
1 answer

How to fix browser/IERC20.sol:4:53: Warning: This declaration shadows an existing declaration

I believe the issue is the reuse ...READ MORE

Oct 1, 2018 in Blockchain by slayer
 • 29,370 points • 2,070 views
0 votes
1 answer

Is it possible to send eth to a contract through its constructor from another contract?

I found the solution for this: pragma solidity ...READ MORE

Sep 26, 2018 in Blockchain by slayer
 • 29,370 points • 2,285 views
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