Recently I wanted to sign up my kid for a school event with limited number of participants. The sign up process was a kind of "first come, first served". Unfortunately by the time I heard about the event, all the places were booked.
My idea is to create a web site where people can register for an event. It should be transparent how many spots are available and what's the due date for registration. After the due date, the application automatically and randomly chooses who got successfully signed up.
- Event is created with due date of 1st December 2021, 10 spots available.
- Link to this event is distributed externally (e.g. by email).
- People get registered for the event and wait for the due date. Let's say there are 22 people who registered and wait.
- At the due date, the application randomly chooses among the registrants, 10 lucky ones who got signed up.
- The result of sign up proess is avaiable on the event site.
This dapp is available on Heroku hosting https://sign-me-up-dapp.herokuapp.com/
client - UI code of nodejs application, written with https://ejs.co/, HTML5, https://jquery.com/ and https://getbootstrap.com/
contracts - Solidity contracts
migrations - Solidity contracts migrations
test - Solidity contracts js tests
Install metamask plugin for your browser. It's a crypto wallet that you'll need to interact with this site. More on https://metamask.io/
The easiets way is to run it on some linux distribution or in case of Windows use WSL like Ubuntu on WSL
Install Node, npm, heroku-cli (optional) and truffle
This app has been tested with:
Clone the project with
git clone git@github.com:walaniam/blockchain-developer-bootcamp-final-project.gitIn project root dir initialize truffle node app (solidity contracts)
npm installInitialize client dapp
cd client
npm installYou need to initialize the network and set one of auto-created account addresses into .env file.
npm start
Once local network is started you'll see some sample accounts with their private keys that can be used locally. Import some of the private keys into your metamask browser plugin - you can then use these accounts for local development.
Create .env file in project root dir. Fill in one of the development account address into this file. This account will be the owner of deployed contract.
# Account address of contract owner in develop network
DEVELOP_FROM=<set one of the account addresses here>Stop the network by ctrl+c (or any other that exits the shell). You are now ready for the development.
Start the network
npm start
In the network shell run
migrate --network develop
To test contracts run following command in project root dir. It uses default test network as desribed here
npm test
In project root dir run below commands
cd client
npm start
Then open in the browser http://localhost:5000/
For ropsten development create .env_ropsten file in project dir with following variables
# Metamask mnemonic
MNEMONIC=
# Infura project URL
INFURA_URL=
# Account address of contract owner in ropsten network
ROPSTEN_FROM=Run npm start and then migrate --network ropsten
This applications uses https://elements.heroku.com/buildpacks/timanovsky/subdir-heroku-buildpack build pack. UI is built basing on https://devcenter.heroku.com/articles/getting-started-with-nodejs sample application.
Create and configure the app
APP_NAME=<your app name here>
heroku login
heroku create -a $APP_NAME --region eu
git remote rm heroku
git remote add heroku https://git.heroku.com/${APP_NAME}.git
# Add build pack for subdir nodejs app located in client directory
heroku buildpacks:clear
heroku buildpacks:set https://github.com/timanovsky/subdir-heroku-buildpack
heroku buildpacks:add heroku/nodejs
heroku config:set PROJECT_PATH=client
Deploy app
# From development branch named html
git push heroku html:main
# From main branch
git push heroku main
Check logs
heroku logs --tail
https://etherscan.io/address/0x3A295cb57782AF8F032b9b06Be276908A3aeC5F6