loopback-connector-web3

This module is an Ethereum Web3 connector for LoopBack.

Configuration

The connector now supports two modes:

Refer to an existing solidity project

The datasource configures the solidityProject property to point to an existing solidity project. The connector automatically builds models from smart contracts discovered in the solidity project.

server/datasources.json:

{
  "web3": {
    "url": "http://localhost:8545",
    "name": "web3",
    "connector": "loopback-connector-web3",
    "solidityProject": "../channel-contracts"
  },
  ...
}

Define models with ethereum extensions

We can use lb model to create models representing Ethereum contracts.

common/models/global-click.json:

{
  "name": "GlobalClick",
  "base": "Model",
  "idInjection": true,
  "options": {
    "validateUpsert": true,
    "ethereum": {
      "contract": {}
    }
  },
  "properties": {},
  "validations": [],
  "relations": {},
  "acls": [],
  "methods": {}
}

common/models/global-click.js:

'use strict';

module.exports = function(GlobalClick) {
  // Programmatically configures the ethereum contract JSON interface
  const CONTRACT = require('channel-contracts').contracts.Demo1;
  GlobalClick.settings.ethereum.contract = CONTRACT;
};

server/model-config.json

{
  "GlobalClick": {
    "dataSource": "web3",
    "public": true
  },
  ...
}

Run migration of smart contracts

The Web3 connector is able to migrate corresponding smart contracts if the datasource refers to a solidity project. For example,

server/boot/migrate.js

'use strict';

module.exports = function(app, cb) {
  const ds = app.dataSources.web3;
  ds.on('connected', () => ds.automigrate(cb));
};

Example

For an example to get you up and running, checkout the payment channels demo.