Learn Cycle, Loopback and Mocha

In this course the developer will learn how to create a LoopBack API and build it out to an API that can be used as a backend for apps. We will start by creating a basic LoopBack API project and gradually enhance it to a production ready API. The API we create defines a few models to persist the data and has custom functionality, validation and hooks added to those models. 

After our data structure is defined we will learn how to extend the functionality of LoopBack by using mixins and components. We will also lock our API down using ACL’s and create a mechanism to automatically define the admin and user roles and create our admin user.   

The last part of the course will show how how to filter the data stored in the API. We will make the API production-ready by adding unit tests, connecting it to MongoDB and we will show how to deploy the app to now.sh.   

LoopBack is a highly-extensible, open-source Node.js framework.

loopback

Build a Node.js REST API with LoopBack

Cycle.js is a framework where your app is described as a simple function taking an event stream as input and outputting an event stream. 

Cycle.js builds on functional and reactive streams and is a JavaScript framework. What does that mean? In the course, André Staltz, the creator of Cycle.js, will explain it to us.

We'll start this course with an empty project and build out our own toy version of Cycle.js to understand exactly what's going on under the hood. When we have a solid base of how Cycle.js works we will move on to use the Cycle.js API and build an app using the Model-View-Intent pattern.

Cycle.js is a framework where your app is described as a simple function taking an event stream as input and outputting an event stream.

cycle

Cycle.js Fundamentals

We are starting to get a better architecture for these UI apps. But we still have a problem of repeating code for the sliders, since they share so much in common in looks and functionality. This lessons shows how we can create a generic labeled slider as a main() function receiving properties as sources.

Create a Generic Cycle.js Component

Our app is not yet a BMI calculator, because it only has two sliders, but doesn't show the calculated BMI number. In this lesson we will learn how to export any stream from a child component and use it in the parent component, in order to display the BMI calculation on the DOM.

Export Values from Components through Sinks in Cycle.js

This lesson shows what can be learned next as a continuation of this course, and gives a recap on the core concepts: main for pure logic, drivers for side effects, run() to connect main and drivers, sources for read effects, sinks for write effects, and nesting Cycle.js apps to work as components.

Overview of Cycle.js

Let's see next how to use the HTTP driver to generate requests and capture responses. We will build a small app to fetch a single piece of data from a REST server and display that on the DOM.

Fetch Data using the Cycle.js HTTP Driver

A relation in LoopBack is a way to associate the data from multiple models with each other. LoopBack supports various types of relations each with a different use case.

In this lesson we will create a second model called Category and create a relation between the Category and the Product models. To do this we will first add a property to the Product model called `categoryId`. This will allow us to store for each Product the category it belongs to. We then move on to create the actual relationships. 

Our first relationship defines that a `Category hasMany Products` and the second one that a `Product belongsTo a Category`.

After defining these relations we will use the API Explorer to see how we can interact with this related data.

Create a relation between two LoopBack models

In this lesson we will look at the filters that can be used to retrieve and manipulate the data stored in LoopBack. 

We will use [Postman](https://www.getpostman.com/) to interact with the `/Categories` and `/Products` endpoints. 

Using the URL parameters we will apply at the various filters LoopBack has to offer: `include`, `order`, `where`, `fields`, `limit` and `offset`. 

Filter model data in LoopBack

In this lesson we look at extending the functionality of LoopBack models by defining a remote method. 

A remote method is a method on a model exposed over a custom REST endpoint. 

Using the `lb remote-method` command we will create the remote method meta-data in `product.json`. We will verify that this got created and that we see the new REST endpoint got added. Then we will create the actual method in `product.js` and enhance it so that the API will return an error if we want to buy a negative amount of products.

Define a remote method on a LoopBack model

In this lesson we will create a dynamic datasource in LoopBack. If the API is started with the environment variable `MONGODB_URL` it will use this url and the `loopback-connector-mongodb` package to store the data in MongoDB.

In the course we will use a local MongoDB instance. If you don't have MongoDB running locally you can always create a [free MongoDB Atlas database](https://egghead.io/lessons/create-a-free-database-on-mongodb-atlas).


Create a MongoDB DataSource in LoopBack

In this lesson you will learn how to persist the data from the memory connector. As the name suggests, the memory connector stores the data in memory. This means that if you restart the server, the data is gone. In development mode it can be useful to store this data in a file, so it gets persisted between server restarts, and it can be easily inspected.

Persist in-memory data to a file when developing Node.js LoopBack API's

In this lesson we will learn to create a development mode for our server. We do this by installing nodemon as a dev dependency and creating a script tag called 'dev'. 

This script tag will execute the command `nodemon server/server.js --watch common --watch server`.  

We can execute this command by running `npm run dev`. 

When running in development mode the server will be automatically restarted when there are changes detected in the `common` and `server` directories.

Setup a development mode in LoopBack API using nodemon

In this lesson we will learn how to protect our API using ACL’s. 

ACL stands for Access Control List and it's function is to control permissions of resources in the API. It does this by keeping a mapping between an API resource and a principal. An API resource as an API endpoint like a remote method or a whole model. A principal in LoopBack are users or applications that can be grouped in a role.

In order to get the API production ready we will protect a selection of our REST endpoints with ACL’s. We will look at how we can obtain an access token and how we can use that in our requests.

Finally we will write some unit tests to make sure that the ACL does what we expect. We enhance our test setup by exporting `request` with is provided by the [supertest](https://www.npmjs.com/package/supertest) library.

In our tests we use `request` to verify that our endpoints return the correct HTTP status code.  

Configure ACL’s to protect the LoopBack API

In this lesson we will look at how to deploy our LoopBack API project using [now](https://zeit.co/now). 

We will install the now client, create an account and deploy our app.

Using `now secrets` features we will store our database connection url which we get by creating a [free MongoDB Atlas database](https://egghead.io/lessons/create-a-free-database-on-mongodb-atlas).

In order to simplify following deployments we will add a `now` key to our `package.json` where we use the `name`, `alias` and `env` parameters to configure our deployments. We will add some npm scripts so we can deploy our app in the desired way using `npm run now`.

Deploy a LoopBack API project using now.sh

In this lesson we will create a free account on monogdb.com. After the account has been created we will create a group in MongoDB Atlas and in that group we create a free cluster. In order to create the cluster we need to provide a username and password. We create our user called `admin` and have the site generate our password for use. Once the cluster is created we look at where we can find the connection string.

Create a free database on MongoDB Atlas

LoopBack is a framework built on top of Express for creating APIs. It allows you to create end-to-end REST APIs that can access data from many data sources such as MondoDB, PostgreSQL, MySQL or other REST APIs.

In this lesson you will learn how to install loopback-cli and create a new LoopBack API project. After creating the basic LoopBack project through the CLI, running the server will give us access to the project and API Explorer urls. The user model will be available to us because user authentication was enabled.

Initialize a LoopBack Node.js Project through the CLI

Once we have a labeled slider component inside the main function, we should be able to create another labeled slider. This lesson teaches how to accomplish that, and make sure those two instances work independently of each other.

Use Multiple Independent Instances of a Cycle.js Component

We added classNames to pre-processing and post-processing steps when calling the LabeledSlider, in order to instances independent of each other. It would be better if we could hide these steps away. This lesson introduces the isolate() helper function to achieve that.

Isolate Component Instances in Cycle.js

This lesson is the first in an introduction to Cycle.js. We will see how to build from scratch a toy version of Cycle.js. See how to use RxJS to create simple web apps, and how to separate logic from effects.

Separate Logic from Effects in Cycle.js

We need to give structure to our application with logic and effects. This lessons shows how we can organize our code into two parts: main() function for logic, and effects functions for effects.

Organize Code in the Main and Effect Functions

How can we show one string on the DOM, and a completely different string on Console log? This lesson shows how we can make our main function return multiple Observables, each one targeted at a different type of effect.

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