Developer Experience - Improve liana api.

app.js

const Liana = require('forest-express-sequelize');
const express = require('express');
const initCollections = require('./collections');
const initModels = require('./models');
const Sequelize = require('sequelize');

const sequelize = new Sequelize({
  dialect: 'sqlite',
  storage: 'database.sqlite',
});

const models = initModels(sequelize);

const app = express();

// We can get rid of modelsDir, because all the models informations are in sequelize and
// mongoose instances.
// Here the example could also work with a factory instead (`const liana = createLiana({...})`).
const liana = new Liana({
  envSecret: process.env.FOREST_ENV_SECRET,
  authSecret: process.env.FOREST_AUTH_SECRET,
  sequelize: models.sequelize,
});

// To initialize a collection, just call a member function. This is a more familiar way to do
// for nodejs users than a static function of the forest-express-sequelize module. It is 
// rarely a good idea to use a module as singleton, difficult to understand what is the inner logic,
// like how the static functions are related to the initialization. Also,
// a singleton forbid to have multiple instances of the liana in the same app.
liana.collection('user', {});

// And we can still put the collections initializations in a folder if we need. This is very
// straightforward, no documentation is needed (and potentially less support), we just do like we
// would do with anything in nodejs. Again familiarity is key.
// Also, we can get rid of the `configDir` option.
initCollections(liana);

app.use(liana.createMiddleware());

collections.js

module.exports = (liana) => {
  liana.collection('post', {});
  liana.collection('comments', {});
};

models.js

module.exports = (sequelize) => {
  const User = sequelize.define('user', {
    // attributes
    firstName: {
      type: Sequelize.STRING,
      allowNull: false
    },
    lastName: {
      type: Sequelize.STRING
      // allowNull defaults to true
    }
  });

  const Post = sequelize.define('post', {
    // attributes
    firstName: {
      type: Sequelize.STRING,
      allowNull: false
    },
    lastName: {
      type: Sequelize.STRING
      // allowNull defaults to true
    }
  });

  return {
    user: User,
    post: Post,
  };
};