Rumbl

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Ready to run in production? Please check our deployment guides.

Chapter 2 : Lay of the Land

We installed Phoenix, which is built using Erlang and OTP for the service layer, Elixir for the language, and Node.js for packaging static assets.
We used the Elixir build tool mix to create a new project and start our server.
Web applications in Phoenix are pipelines of plugs.
The basic flow of traditional applications is endpoint, router, pipeline, controller.
Routers distribute requests.
Controllers call services and set up intermediate data for views.

We created a simple repository. We did so to simplify your plunge into the world of controllers and views.
We created actions, which serve as the main point of control for each request.
We created views, which exist to render templates.
We created templates, which generate HTML for our users.
We employed helpers, which are simple Phoenix functions used in templates.
We used layouts, which are HTML templates that embed an action’s HTML.

We began the chapter by introducing Ecto and announcing our intention to replace the in-memory repository with a database-backed repository using Ecto.
We configured our new database and connected it to OTP, so that Elixir could do the right thing in the event of a Phoenix or Ecto crash.
We created a schema, complete with information about each necessary field.
We created a migration, to help us specify our database tables and automate doing and undoing any database changes.
We created a changeset so Ecto could efficiently track and manage each change requested by our application.
We integrated this change into our application.

We added the comeonin dependency to our project.
We built our own authentication layer.
We built the associated changesets to handle validation of passwords.
We implemented a module plug that loads the user from the session and made it part of our browser pipeline.
We implemented a function plug and used it alongside some specific actions in our controller pipeline.

We converted a private plug into a public function and shared it with our controllers and routers.
You learned how to migrate and roll back changes to the database.
We defined relationships between User and Video schemas and used functions from Ecto to build and retrieve associated data.
You learned that Ecto uses strictly explicit semantics to determine if a relationship is loaded or not.

We used Ecto’s query API, which is independent of the repository API, to do some basic queries.
We used two forms of queries, a keyword list–based syntax and a pipebased syntax.
We used fragments to pass SQL commands through the query API unchanged.
We explored the different ways Ecto queries work with relationships, beyond data preloading.
We wrote constraint-style validations for unique indexes and foreign-key violations.
We learned how to choose between letting constraint errors go and when to report them to the user.

We examined how tests work in Phoenix.
We set up some basic testing functions to insert users and videos, and shared those across all of our potential test cases.
We wrote some basic integration tests, bypassing only our authentication plug.
We used Phoenix test helpers to make multiple assertions in a compact way.
We tested our authentication plug in isolation.
We tested our views.
We tested models with and without side effects.

You learned to use Brunch to support development-time reloading and minimization for production code.
We used generators to create an Ecto migration.
We used changesets to create slugs.
We used protocols to seamlessly build URLs from those new slugs.

Learned to connect to a server-side channel through an ES6 client.
Built a server-side channel with both long-polling and WebSocket support.
Built a simple API to let users join a channel.
Processed inbound messages from OTP with handle_info and channels with handle_in.
Sent broadcast messages with broadcast!.
Authenticated users with Phoenix.Token.
Persisted annotations with Ecto.

Built a counter that demonstrates how some OTP behaviors work.
Looked at several OTP supervision and restart strategies.
Looked at examples of a full OTP service as GenServer.
Learned how tasks wrap behavior and agents encapsulate state.
Implemented an information system abstract front end with concrete backends.
Learned to fetch WolframAlpha results from an HTTP service and share them with our channels.