Lending dApp

Installation

Initial scaffolding thanks to: https://github.com/wespr/truffle-vue

1. Install Truffle and an Ethereum client - like EthereumJS TestRPC. Note I couldn't get this to work on our VMs so I installed them directly on the Mac.

   [sudo] npm install -g truffle // Version 3.0.5+ required.
   [sudo] npm install -g ethereumjs-testrpc
   

2. Pull down the repo and install dependancies

   git clone https://github.com/jsaur/lending-dapp
   npm install
   

3. Launch testrpc in it's own command prompt tab.

   testrpc <options>
   

4. Compile and migrate the contracts.

   truffle compile
   truffle migrate
   

5. Run the webpack server for front-end hot reloading. Smart contract changes do not support hot reloading for now.

   npm run start
   

Tests

This box comes with everything bundled for unit, e2e and truffle contracts testing. The tests are incomplete at the moment.

1. unit and e2e tests.

   npm run test/dapp
   

2. truffle contracts tests.

   npm run test/truffle
   

3. Alternatively you can directly run unit, e2e and truffle contracts tests in one command.

   npm run test
   

Build for production

To build the application for production, use the build command. A production build will be compiled in the dist folder.

npm run build

Metamask

1. Install Metamask in your browser: https://metamask.io/

2. Change network to: Localhost 8545

3. When you started testrpc, it should have printed out a list of available accounts and private keys. Copy one of the private keys.

4. In meta mask, click the circular arrows, then "Import Account", then paste the private key. Now you can spend your test accounts ether.

Browser solidity

I find that writing, compiling and testing solidity smart contracts is easiest using: https://ethereum.github.io/browser-solidity/

Mist

1. Launch Mist against your private network. Need to download it for your Mac first. Install location may vary.

   cd /Volumes/Macintosh HD/Applications/Mist.app/Contents/MacOS
   ./Mist --rpc localhost:8545
   

2. Add contract The address and name are created when running truffle migrate The json interface can be found under build/contracts, the section under "abi"

Note: I've found Mist on testrpc to only be useful for reads - writes fail with a "_signAndSendTransaction not supported" error that seems to be an outstanding Mist issue.

Possible error resolutions

1. If you're getting npm errors try:

   npm update --scripts-prepend-node-path=auto
   

2. If you're getting 'out of gas' errors, increase the gas in truffle.js

   gas: 460000000
   

3. If you're getting 'Exceeds block gas limit' errors, increase the gas limit on testrpc

   testrpc --gasLimit 50000000
   

4. If you're getting 'invalid opt code' errors, try starting over

   truffle compile
   truffle migrate --reset
   

5. If you're getting javascript errors when interacting with you contracts, double check the 'abi' section of your contract json in /build/contracts and compare to what the function actually looks like in Solidity. Sometimes truffle compile doesn't update these properly. If you delete all the files in build/contracts and then recompile everything it often fixes it.

   npm run truffle migrate --reset --compile-all
   

6. Metamask issues: sometimes Metamask is unresponsive. I've found the best way is to disable, then re-enable metamask from the chrome extensions page.