Create an online marketplace that operates on the blockchain.
There are a list of stores on a central marketplace where shoppers can purchase goods posted by the store owners.
The central marketplace is managed by a group of administrators. Admins allow store owners to add stores to the marketplace. Store owners can manage their store’s inventory and funds. Shoppers can visit stores and purchase goods that are in stock using cryptocurrency.
Refer to the below URL for complete details about the requirement: https://github.com/wtcalok/ethmarket/blob/master/docs/Requirements.md
$ mkdir marketplace
$ cd marketplace/
Clone / Download the files in this repository: https://github.com/wtcalok/ethmarket.git
git clone https://github.com/wtcalok/ethmarket.git
cd to the main project directory and run the following command to ensure that dependencies are installed
npm install
Use the following command to deploy / redeploy the contract in the test environment:
truffle migrate --reset --compile-all --network ganache
Run the following command to see the eth gas report
npm install --save-dev eth-gas-reporter
Refer to the truffle.js file for specific configuration.
Go to the contract folder and run the following command to test the positive scenarios:
truffle test --network ganache ./test/1_HappyPath.js
Also, run the following command, which specifies how to test the negative scenarios and exceptions:
truffle test --network ganache
emergencyFlag to true and run 1_HappyPath.js test to see what happens when you use the circuit breaker pattern.
Reset this flag to false to test the scenarios in the regular case.
As part of this project I have also used EIP20 tokens to help with the discount functionality in the market place. While the front-end doesn't talk anything explicitly about this, you may need to transfer tokens explicitly to the store owners to see the functionality in actions.
Refer to unit test case to see how to transfer tokens from SuperAdmin to Store Owners.
Go to the dapp directory and run the following command to install all the dependencies
npm install
Run the following command to run the http server:
ng serve
Open browser and open the APP by visiting the URL: http://localhost:4200/
- By default the first account in Ganache will be used as coinbase and this account is considered the SuperAdmin. Also, it gets added as Admin by default. So, you need to first copy this account address and use that for login. There is no password or security, so it will just take you inside the DAPP
- After this you can add more Admin and Store owners
- You can use the corresponding address to perform related actions
- By default every account is a shopping account.
- Login with Metamask and choose localhost:8545 as the network. Make sure that your ganache runs on this port.
Steps taken to avoid common attacks are described in avoiding_common_attacks.md. https://github.com/wtcalok/ethmarket/blob/master/docs/avoiding_common_attacks.md
The design patterns used in the project are described in design_pattern_descision.md. https://github.com/wtcalok/ethmarket/blob/master/docs/design_pattern_desicions.md
Please visit below URL to see the deployed contract on Rinkeby https://rinkeby.etherscan.io/address/0x257cceeaeca1f05eb66af7aa3571a322f2125fdd Add following code on top of the truffle.js file
require('dotenv').config();
var HDWalletProvider = require("truffle-hdwallet-provider");
var mnemonic = process.env["NEMONIC"];
var providerKey = process.env["ENDPOINT_KEY"];
You need to add the following network options in truffle.js file
rinkeby:{
host: "localhost",
provider: function() {
return new HDWalletProvider(mnemonic, "https://rinkeby.infura.io/v3/"+providerKey);
},
network_id:4
, gas : 6700000
, gasPrice : 10000000000
}
Also, somehow the contract seems to be needing more gas, so please do use solc configuration as shown below:
solc: {
optimizer: {
enabled: true,
runs: 200
}
}
Also, create a .env file in the root folder of the project and add the following content in that file:
NEMONIC="orphan blur library flame donkey damp destroy shallow kind float warrior badge"
ENDPOINT_KEY="9f110b8c7a7a41febca9c060f2d90e53"
Install HDWalletProvider to sign transactions for addresses derived from a 12-word mnemonic
npm install truffle-hdwallet-provider
Install dotenv, a zero-dependency module, that loads environment variables from a .env file into process.env:
npm install dotenv
You may like to add your own nemonic and Infura endpoint key to avoid surprizes.
For more details about INFURA deployment, please visit below URL: https://truffleframework.com/tutorials/using-infura-custom-provider
You may need to run the following command in the main project directory as well as the dapp directory:
npm install
Increase the block gas limit in Ganache. For example, I have set a value of 9998888890.
Also, refer to the network config options in the truffle.js file and adjust gas limit if needed.
On windows machine you may need to copy the truffle.js file into truffle-config.js file.
During the purchase of the product, the ether transfer from shopper's account to the store contract's account work alright. However, when I am trying to do the same from the DAPP, it is still causing the issue. Comment out the transfer (myAddress.transfer( finalAmountToBePaid );) call in buyProductFromStore method to test the rest of the functionality.
Sometimes Metamask gives nonce related issue. In such case, please clean up Metamask by following the below steps
- Press the Metamask icon
- reset Metamask by going into Settings > Reset Account
- Logout
- Login again
If needed, do delete existing accounts and import the accounts corresponding to your Ganache.
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