# phoenix-chat-example
**Repository Path**: mirrors_dwyl/phoenix-chat-example
## Basic Information
- **Project Name**: phoenix-chat-example
- **Description**: π¬ The Step-by-Step Beginners Tutorial for Building, Testing & Deploying a Chat app in Phoenix 1.7 [Latest] π
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No
## Statistics
- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-08
- **Last Updated**: 2026-01-17
## Categories & Tags
**Categories**: Uncategorized
**Tags**: None
## README
# Phoenix Chat Example
[](https://codecov.io/github/dwyl/phoenix-chat-example?branch=main)
[](https://github.com/dwyl/phoenix-chat-example/issues)
[](https://github.com/dwyl/phoenix-chat-example)
[](https://hex.pm/packages/phoenix)
_Try_ it:
[**phoenix-chat**.fly.dev](https://phoenix-chat.fly.dev/)
A ***step-by-step tutorial*** for building, testing
and _deploying_ a Chat app in Phoenix!
- [Phoenix Chat Example](#phoenix-chat-example)
- [Why?](#why)
- [What?](#what)
- [Who?](#who)
- [_How_?](#how)
- [0. Pre-requisites (_Before you Start_)](#0-pre-requisites-before-you-start)
- [_Check_ You Have Everything _Before_ Starting](#check-you-have-everything-before-starting)
- [First _Run_ the _Finished_ App](#first-run-the-finished-app)
- [Clone the Project:](#clone-the-project)
- [Install the Dependencies](#install-the-dependencies)
- [Run the App](#run-the-app)
- [1. _Create_ The _App_](#1-create-the-app)
- [Run the Tests](#run-the-tests)
- [2. _Create_ the (WebSocket) "_Channel_"](#2-create-the-websocket-channel)
- [3. Update the Template File (UI)](#3-update-the-template-file-ui)
- [3.1 Update Layout Template](#31-update-layout-template)
- [3.2 Update the `page_controller_test.exs`](#32-update-the-page_controller_testexs)
- [4. Update the "Client" code in App.js](#4-update-the-client-code-in-appjs)
- [4.1 Comment Out Lines in `user_socket.js`](#41-comment-out-lines-in-user_socketjs)
- [Storing Chat Message Data/History](#storing-chat-message-datahistory)
- [5. Generate Database Schema to Store Chat History](#5-generate-database-schema-to-store-chat-history)
- [6. Run the Ecto Migration (_Create The Database Table_)](#6-run-the-ecto-migration-create-the-database-table)
- [6.1 Review the Messages Table Schema](#61-review-the-messages-table-schema)
- [7. Insert Messages into Database](#7-insert-messages-into-database)
- [8. Load _Existing_ Messages (_When Someone Joins the Chat_)](#8-load-existing-messages-when-someone-joins-the-chat)
- [9. Send Existing Messages to the Client when they Join](#9-send-existing-messages-to-the-client-when-they-join)
- [10. _Checkpoint_: Our Chat App Saves Messages!! (_Try it_!)](#10-checkpoint-our-chat-app-saves-messages-try-it)
- [Testing our App (_Automated Testing_)](#testing-our-app-automated-testing)
- [11. Run the Default/Generated Tests](#11-run-the-defaultgenerated-tests)
- [12. Understanding The Channel Tests](#12-understanding-the-channel-tests)
- [12.1 _Analyse_ a Test](#121-analyse-a-test)
- [13. What is _Not_ Tested?](#13-what-is-not-tested)
- [13.1 Add `excoveralls` as a (Development) Dependency to `mix.exs`](#131-add-excoveralls-as-a-development-dependency-to-mixexs)
- [13.2 Create a _New File_ Called `coveralls.json`](#132-create-a-new-file-called-coverallsjson)
- [13.3 Run the Tests with Coverage Checking](#133-run-the-tests-with-coverage-checking)
- [13.4 Write a Test for the Untested Function](#134-write-a-test-for-the-untested-function)
- [Authentication](#authentication)
- [Adding `Presence` to track who's online](#adding-presence-to-track-whos-online)
- [Continuous Integration](#continuous-integration)
- [Deployment!](#deployment)
- [What _Next_?](#what-next)
- [Inspiration](#inspiration)
- [Recommended Reading / Learning](#recommended-reading--learning)
## Why?
Chat apps are the
[`"Hello World"`](https://en.wikipedia.org/wiki/%22Hello,_World!%22_program)
of
[real time](https://en.wikipedia.org/wiki/Real-time_computing)
examples.
Sadly, **_most_ example apps** show a few **basics**
and then **ignore the rest** ... π€·ββοΈ
So **beginners** are often left **lost** or **confused** as to
what they should _do_ or learn _next_!
Very _few_ tutorials consider
**Testing, Deployment, Documentation** or _other_ "**Enhancements**"
which are all part of the "***Real World***"
of building and running apps;
so those are topics we **_will_ cover** to "_fill in the gaps_".
We wrote _this_ tutorial to be **_easiest_ way to learn `Phoenix`**,
`Ecto` and `Channels` with a **_practical_ example _anyone_ can follow**.
This is the example/tutorial we _wished_ we had
when we were learning `Elixir`, `Phoenix` ...
If you find it useful, please β π Thanks!
## What?
A simple step-by-step tutorial showing you how to:
+ **Create** a **Phoenix App** from _scratch_
(_using the `mix phx.new chat` "generator" command_)
+ Add a "Channel" so your app can communicate over
[**WebSockets**](https://en.wikipedia.org/wiki/WebSocket).
+ Implement a _basic_ ***front-end*** in _plain_ JavaScript
(_ES5 without any libraries_) to interact with Phoenix
(_send/receive messages via WebSockets_)
+ Add a simple "**Ecto**" **schema** to define
the **Database Table** (_to store messages_)
+ **Write** the functions ("CRUD") to _save_
message/sender data to a database table.
+ **Test** that everything is working as expected.
+ ***Deploy*** to **`Fly.io`** so you can _show_ people your creation!
_Initially_, we _deliberately_ skip over configuration files
and "_Phoenix Internals_"
because you (_beginners_) _don't need_ to know about them to get _started_.
But don't worry, we will return to them when _needed_.
We favour "_just-in-time_" (_when you need it_) learning
as it's _immediately_ obvious and _practical_ ***why***
we are learning something.
## Who?
This example is for ***complete beginners***
as a "***My First Phoenix***" App.
We try to _assume_ as little as possible,
but if you think we "_skipped a step_"
or you feel "_stuck_" for any reason,
or have _any_ questions (_related to this example_),
please open an issue on GitHub!
Both the @dwyl and Phoenix communities are _super **beginner-friendly**_,
so don't be afraid/shy.
Also, by asking questions, you are helping everyone
that is or might be stuck with the _same_ thing!
+ **Chat App _specific_** questions:
[dwyl/**phoenix-chat-example**/issues](https://github.com/dwyl/phoenix-chat-example/issues)
+ **General** Learning Phoenix questions:
[dwyl/learn-**phoenix-framework**/issues](https://github.com/dwyl/learn-phoenix-framework/issues)
# _How_?
These instructions show you how to _create_ the Chat app
_from scratch_.
## 0. Pre-requisites (_Before you Start_)
1. **Elixir _Installed_** on your **local machine**.
see:
[dwyl/learn-elixir#**installation**](https://github.com/dwyl/learn-elixir#installation)
e.g:
```sh
brew install elixir
```
> _**Note**: if you already have `Elixir` installed on your Mac,
and just want to upgrade to the latest version, run:_
**`brew upgrade elixir`**
1. **Phoenix** framework **installed**.
see:
[hexdocs.pm/phoenix/installation.html](https://hexdocs.pm/phoenix/installation.html)
e.g:
```sh
mix archive.install hex phx_new
```
1. PostgreSQL (Database Server) installed (_to save chat messages_)
see:
[dwyl/**learn-postgresql#installation**](https://github.com/dwyl/learn-postgresql#installation)
1. Basic **Elixir Syntax** knowledge will help,
please see:
[dwyl/**learn-elixir**](https://github.com/dwyl/learn-elixir)
1. Basic **JavaScript** knowledge is _advantageous_
(_but not essential as the "front-end" code
is quite basic and well-commented_).
see:
[dwyl/Javascript-the-Good-Parts-notes](https://github.com/dwyl/Javascript-the-Good-Parts-notes)
### _Check_ You Have Everything _Before_ Starting
Check you have the _latest version_ of **Elixir**
(_run the following command in your terminal_):
```sh
elixir -v
```
You should see something like:
```sh
Erlang/OTP 25 [erts-13.1.1] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1] [jit] [dtrace]
Elixir 1.14.1 (compiled with Erlang/OTP 25)
```
Check you have the **latest** version of **Phoenix**:
```sh
mix phx.new -v
```
You should see:
```sh
Phoenix installer v1.7.0-rc.2
```
> **Note**: if your `Phoenix` version is _newer_,
> Please feel free to update this doc! π
> We try our best to keep it updated ...
> but _your_ contributions are always welcome!
> In this tutorial,
> we are using
> [Phoenix 1.7-rc2](https://github.com/phoenixframework/phoenix/blob/master/CHANGELOG.md#170-rc2-2023-01-13),
> the second release candidate
> for `Phoenix 1.7`.
> At the time of writing,
> if you install Phoenix,
> the *latest stable version* is not `v1.7`.
> To use this version,
> follow the official guide (don't worry, it's just running one command!)
> -> https://www.phoenixframework.org/blog/phoenix-1.7-released
>
> However, if you are reading this after its release,
> `v1.7` will be installed for you,
> and you should see
> `Phoenix installer v1.7.0`
> in your terminal.
_Confirm_ **PostgreSQL** is running (_so the App can store chat messages_)
run the following command:
```sh
lsof -i :5432
```
You should see output _similar_ to the following:
```sh
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
postgres 529 Nelson 5u IPv6 0xbc5d729e529f062b 0t0 TCP localhost:postgresql (LISTEN)
postgres 529 Nelson 6u IPv4 0xbc5d729e55a89a13 0t0 TCP localhost:postgresql (LISTEN)
```
This tells us that PostgreSQL is "_listening_" on TCP Port `5432`
(_the default port_)
If the `lsof` command does not yield any result
in your terminal,
run:
```sh
pg_isready
```
It should print the following:
```sh
/tmp:5432 - accepting connections
```
With all those
["pre-flight checks"](https://en.wikipedia.org/wiki/Preflight_checklist)
performed, let's _fly_! π
## First _Run_ the _Finished_ App
_Before_ you attempt to build the Chat App from scratch,
clone and run the _finished_ working version
to get an idea of what to expect.
### Clone the Project:
In your terminal run the following command to clone the repo:
```sh
git clone git@github.com:dwyl/phoenix-chat-example.git
```
### Install the Dependencies
Change into the `phoenix-chat-example` directory
and install both the `Elixir` and `Node.js` dependencies
with this command:
```sh
cd phoenix-chat-example
mix setup
```
### Run the App
Run the Phoenix app with the command:
```sh
mix phx.server
```
If you open the app
[localhost:4000](http://localhost:4000)
in two more web browsers,
you can see the chat messages
displayed in all of them
as soon as you hit the Enter key:
Now that you have confirmed that the _finished_
phoenix chat app works on your machine,
it's time to _build_ it from scratch!
Change directory:
```sh
cd ..
```
And start building!
## 1. _Create_ The _App_
In your terminal program on your localhost,
type the following command to create the app:
```sh
mix phx.new chat --no-mailer --no-dashboard --no-gettext
```
That will create the directory structure and project files.
> We are running the
> [`mix phx.new` command](https://hexdocs.pm/phoenix/Mix.Tasks.Phx.New.html)
> with the `--no-mailer` `--no-dashboard` `--no-gettext` arguments
> because we don't want our project
> to generate mailer files,
> to include a `Phoenix.LiveDashboard`
> and generate `gettext` files
> (for [`i18n`](https://en.wikipedia.org/wiki/Internationalization_and_localization)).
When asked to "***Fetch and install dependencies***? [Yn]",
Type Y in your terminal,
followed by the Enter (Return) key.
You should see:
Change directory into the `chat` directory by running the suggested command:
```sh
cd chat
```
Now run the following command:
```sh
mix setup
```
> _**Note**: at this point there is already an "App"
it just does not **do** anything (yet) ...
you **can** run `mix phx.server`
in your terminal - don't worry if you're seeing error
messages, this is because we haven't created our database yet.
We will take care of that in [step 6](#6-createconfigure-database)!
For now, open [http://localhost:4000](http://localhost:4000)
in your browser
and you will see the `default`
"Welcome to Phoenix" homepage:_
Shut down the Phoenix server in your terminal
with the
ctrl+C
command.
### Run the Tests
In your terminal window, run the following command:
```
mix test
```
You should see output similar to the following:
```sh
Generated chat app
.....
Finished in 0.02 seconds (0.02s async, 0.00s sync)
5 tests, 0 failures
Randomized with seed 84184
```
Now that we have confirmed that everything is working (all tests pass),
let's continue to the _interesting_ part!
## 2. _Create_ the (WebSocket) "_Channel_"
Generate the (WebSocket) channel to be used in the chat app:
```sh
mix phx.gen.channel Room
```
> If you are prompted to confirm installation of a new socket handler
type `y` and hit the `[Enter]` key.
This will create **three files**:
```sh
* creating lib/chat_web/channels/room_channel.ex
* creating test/chat_web/channels/room_channel_test.exs
* creating test/support/channel_case.ex
```
in addition to creating **two more files**:
```sh
* creating lib/chat_web/channels/user_socket.ex
* creating assets/js/user_socket.js
```
The `room_channel.ex` file handles receiving/sending messages
and the `room_channel_test.exs` tests basic interaction with the channel.
We'll focus on the `socket` files created afterwards.
(_Don't worry about this yet, we will look at the test file in step 14 below_!)
We are informed that we need to update a piece of code in our app:
```sh
Add the socket handler to your `lib/chat_web/endpoint.ex`, for example:
socket "/socket", ChatWeb.UserSocket,
websocket: true,
longpoll: false
For the front-end integration, you need to import the `user_socket.js`
in your `assets/js/app.js` file:
import "./user_socket.js"
```
The generator asks us to import the client code in the frontend.
Let's do that later. For now, open the `lib/chat_web/endpoint.ex` file and follow the instructions.
After this, open the file called `/lib/chat_web/channels/user_socket.ex`
and change the line:
```elixir
channel "room:*", ChatWeb.RoomChannel
```
to:
```elixir
channel "room:lobby", ChatWeb.RoomChannel
```
Check the change [here](https://github.com/dwyl/phoenix-chat-example/blob/0faa7f18ea6d7790e027ace5147cd1740040a75e/lib/chat_web/channels/user_socket.ex#L11).
This will ensure that whatever messages that are sent to `"room:lobby"` are routed to our `RoomChannel`.
The previous `"room.*` meant that any subtopic within `"room"` were routed.
But for now, let's narrow down to just one subtopic :smile:.
> For more detail on Phoenix Channels,
(_we highly recommend you_) read:
https://hexdocs.pm/phoenix/channels.html
## 3. Update the Template File (UI)
Open the the
[`/lib/chat_web/controllers/page_html/home.html.heex`](/lib/chat_web/controllers/page_html/home.html.heex)
file
and _copy-paste_ (_or type_) the following code:
```html
```
This is the _basic_ form we will use to input Chat messages.
The classes e.g. `w-full` and `items-center`
are [`TailwindCSS`](https://tailwindcss.com/)
classes to _style_ the form.
Phoenix includes Tailwind by default so you can get up-and-running
with your App/Idea/"MVP"!
> If you're new to `Tailwind`,
please see:
[dwyl/**learn-tailwind**](https://github.com/dwyl/learn-tailwind)
>
> If you have questions about any
of the **`Tailwind`** classes used,
please spend 2 mins Googling
or searching the official (superb!) docs:
[tailwindcss.com/docs](https://tailwindcss.com/docs)
and then if you're still stuck, please
[open an issue](https://github.com/dwyl/learn-tailwind/issues).
Your `home.html.heex` template file should look like this:
[`/lib/chat_web/controllers/page_html/home.html.heex`](https://github.com/dwyl/phoenix-chat-example/blob/6d070dd27a69572cca6e35f0703aa535c0201a3c/lib/chat_web/controllers/page_html/home.html.heex)
### 3.1 Update Layout Template
Open the `lib/chat_web/components/layouts/root.html.heex` file
and locate the `` tag.
Replace the contents of the `` with the following code:
```html
Phoenix Chat Example
<%= @inner_content %>
```
Your `root.html.heex` template file should look like this:
[`/lib/chat_web/components/layouts/root.html.heex`](https://github.com/dwyl/phoenix-chat-example/blob/6d070dd27a69572cca6e35f0703aa535c0201a3c/lib/chat_web/components/layouts/root.html.heex)
At the end of this step, if you run the Phoenix Server `mix phx.server`,
and view the App in your browser it will look like this:
So it's already starting to look like a basic Chat App.
Sadly, since we changed the copy of the `home.html.heex`
our `page_controller_test.exs` now fails:
Run the command:
```sh
mix test
```
```
1) test GET / (ChatWeb.PageControllerTest)
test/chat_web/controllers/page_controller_test.exs:4
Assertion with =~ failed
code: assert html_response(conn, 200) =~ "Peace of mind from prototype to production"
```
Thankfully this is easy to fix.
### 3.2 Update the `page_controller_test.exs`
Open the `test/chat_web/controllers/page_controller_test.exs` file
and replace the line:
```elixir
assert html_response(conn, 200) =~ "Peace of mind from prototype to production"
```
With:
```elixir
assert html_response(conn, 200) =~ "Phoenix Chat Example"
```
Now if you run the tests again, they will pass:
```
mix test
```
Sample output:
```
........
Finished in 0.1 seconds (0.09s async, 0.06s sync)
8 tests, 0 failures
Randomized with seed 275786
```
## 4. Update the "Client" code in App.js
Open
`assets/js/app.js`,
uncomment and change the line:
```js
import socket from "./user_socket.js"
```
With the line _uncommented_,
our app will import the `socket.js` file
which will give us WebSocket functionality.
Then add the following JavaScript ("Client") code
to the bottom of the file:
```js
/* Message list code */
const ul = document.getElementById('msg-list'); // list of messages.
const name = document.getElementById('name'); // name of message sender
const msg = document.getElementById('msg'); // message input field
const send = document.getElementById('send'); // send button
const channel = socket.channel('room:lobby', {}); // connect to chat "room"
channel.join(); // join the channel.
// Listening to 'shout' events
channel.on('shout', function (payload) {
render_message(payload)
});
// Send the message to the server on "shout" channel
function sendMessage() {
channel.push('shout', {
name: name.value || "guest", // get value of "name" of person sending the message. Set guest as default
message: msg.value, // get message text (value) from msg input field.
inserted_at: new Date() // date + time of when the message was sent
});
msg.value = ''; // reset the message input field for next message.
window.scrollTo(0, document.documentElement.scrollHeight) // scroll to the end of the page on send
}
// Render the message with Tailwind styles
function render_message(payload) {
const li = document.createElement("li"); // create new list item DOM element
// Message HTML with Tailwind CSS Classes for layout/style:
li.innerHTML = `
`
// Append to list
ul.appendChild(li);
}
// Listen for the [Enter] keypress event to send a message:
msg.addEventListener('keypress', function (event) {
if (event.key === `Enter` && msg.value.length > 0) { // don't sent empty msg.
sendMessage()
}
});
// On "Send" button press
send.addEventListener('click', function (event) {
if (msg.value.length > 0) { // don't sent empty msg.
sendMessage()
}
});
// Date formatting
function formatDate(datetime) {
const m = new Date(datetime);
return m.getUTCFullYear() + "/"
+ ("0" + (m.getUTCMonth()+1)).slice(-2) + "/"
+ ("0" + m.getUTCDate()).slice(-2);
}
// Time formatting
function formatTime(datetime) {
const m = new Date(datetime);
return ("0" + m.getUTCHours()).slice(-2) + ":"
+ ("0" + m.getUTCMinutes()).slice(-2) + ":"
+ ("0" + m.getUTCSeconds()).slice(-2);
}
```
> Take a moment to read the JavaScript code
and confirm your understanding of what it's doing.
Hopefully the in-line comments are self-explanatory,
but if _anything_ is unclear, please ask!
At this point your `app.js` file should look like this:
[`/assets/js/app.js`](https://github.com/dwyl/phoenix-chat-example/blob/f45afee52570e07d43b7e3652564d24857a32bd7/assets/js/app.js)
### 4.1 Comment Out Lines in `user_socket.js`
By default the phoenix channel (client)
will subscribe to the generic room: `"topic:subtopic"`.
Since we aren't going to be using this,
we can avoid seeing any
**`"unable to join: unmatched topic"`** errors in our browser/console
by simply commenting out a few lines in the `user_socket.js` file.
Open the file in your editor and locate the following lines:
```JavaScript
let channel = socket.channel("room:42", {})
channel.join()
.receive("ok", resp => { console.log("Joined successfully", resp) })
.receive("error", resp => { console.log("Unable to join", resp) })
```
Comment out the lines so they will not be executed:
```JavaScript
//let channel = socket.channel("room:42", {})
//channel.join()
// .receive("ok", resp => { console.log("Joined successfully", resp) })
// .receive("error", resp => { console.log("Unable to join", resp) })
```
Your `user_socket.js` should now look like this:
[`/assets/js/user_socket.js`](https://github.com/dwyl/phoenix-chat-example/blob/f45afee52570e07d43b7e3652564d24857a32bd7/assets/js/user_socket.js)
> If you later decide to tidy up your chat app, you can **`delete`**
these commented lines from the file.
We are just keeping them for reference
of how to join channels and receive messages.
If you are running the app,
try to fill the `name` and `message` fields
and click `Enter` (or press `Send`).
The message should appear
on different windows!
With this done, we can proceed.
### Storing Chat Message Data/History
If we didn't _want_ to _save_ the chat history,
we could just _deploy_ this App _immediately_
and we'd be done!
> In fact, it could be a "_use-case_" / "_feature_"
to have "_ephemeral_" chat without _any_ history ...
> see: http://www.psstchat.com/.
>
> But we are _assuming_ that _most_ chat apps save history
> so that `new` people joining the "channel" can see the history
> and people who are briefly "absent" can "catch up" on the history.
## 5. Generate Database Schema to Store Chat History
Run the following command in your terminal:
```sh
mix phx.gen.schema Message messages name:string message:string
```
You should see the following output:
```sh
* creating lib/chat/message.ex
* creating priv/repo/migrations/20230203114114_create_messages.exs
Remember to update your repository by running migrations:
$ mix ecto.migrate
```
Let's break down that command for clarity:
+ `mix phx.gen.schema` - the mix command to create a new schema (database table)
+ `Message` - the singular name for record in our messages "collection"
+ `messages` - the name of the collection (_or database table_)
+ `name:string` - the name of the person sending a message, stored as a `string`.
+ `message:string` - the message sent by the person, also stored as a `string`.
The line `creating lib/chat/message.ex` creates the "schema"
for our Message database table.
Additionally a migration file is created, e.g:
`creating priv/repo/migrations/20230203114114_create_messages.exs`
The "_migration_" actually _creates_ the database table in our database.
## 6. Run the Ecto Migration (_Create The Database Table_)
In your terminal run the following command to create the `messages` table:
```sh
mix ecto.migrate
```
> For _context_ we recommend reading:
[hexdocs.pm/ecto_sql/**Ecto.Migration**.html](https://hexdocs.pm/ecto_sql/Ecto.Migration.html)
You should see the following in your terminal:
```sh
11:42:10.130 [info] == Running 20230203114114 Chat.Repo.Migrations.CreateMessages.change/0 forward
11:42:10.137 [info] create table messages
11:42:10.144 [info] == Migrated 20230203114114 in 0.0s
```
### 6.1 Review the Messages Table Schema
If you open your PostgreSQL GUI (_e.g: [pgadmin](https://www.pgadmin.org)_)
you will see that the messages table has been created
in the `chat_dev` database:
You can view the table schema by "_right-clicking_" (_`ctrl + click` on Mac_)
on the `messages` table and selecting "properties":
> _**Note**: For sections 7, 8, and 9 we will be fleshing out how our code
> "handles" the different events that can occur in our chat app._
>
> _Phoenix abstracts away much of the underlying message-passing logic in
> Elixir's process communication (for more info on how Elixir processes
> communicate, read [here](https://hexdocs.pm/elixir/processes.html))._
>
> _In Phoenix, events/messages sent from the client are automatically
> routed to the corresponding handler functions based on the event name,
> making message handling seamless and straightforward!._
## 7. Insert Messages into Database
Open the `lib/chat_web/channels/room_channel.ex` file
and inside the function `def handle_in("shout", payload, socket) do`
add the following line:
```elixir
Chat.Message.changeset(%Chat.Message{}, payload) |> Chat.Repo.insert
```
So that your function ends up looking like this:
```elixir
def handle_in("shout", payload, socket) do
Chat.Message.changeset(%Chat.Message{}, payload) |> Chat.Repo.insert
broadcast socket, "shout", payload
{:noreply, socket}
end
```
If you noticed earlier, in our `assets/js/app.js` file, we used the function
`sendMessage()` to *push* our message to the server on the "shout" event.
Phoenix routes the message to the server-side
`handle_in("shout", payload, socket)` function because the event name
matches 'shout'.
In this function, we handle the payload (which is the message text and
any other data) and insert it into our database. _Neat!_
## 8. Load _Existing_ Messages (_When Someone Joins the Chat_)
Open the `lib/chat/message.ex` file and import `Ecto.Query`:
```elixir
defmodule Chat.Message do
use Ecto.Schema
import Ecto.Changeset
import Ecto.Query # add Ecto.Query
```
Then add a new function to it:
```elixir
def get_messages(limit \\ 20) do
Chat.Message
|> limit(^limit)
|> order_by(desc: :inserted_at)
|> Chat.Repo.all()
end
```
This function accepts a single parameter `limit` to only return a fixed/maximum
number of records.
It uses Ecto's `all` function to fetch all records from the database.
`Message` is the name of the schema/table we want to get records for,
and limit is the maximum number of records to fetch.
## 9. Send Existing Messages to the Client when they Join
In the `/lib/chat_web/channels/room_channel.ex` file create a new function:
```elixir
@impl true
def handle_info(:after_join, socket) do
Chat.Message.get_messages()
|> Enum.reverse() # revers to display the latest message at the bottom of the page
|> Enum.each(fn msg -> push(socket, "shout", %{
name: msg.name,
message: msg.message,
inserted_at: msg.inserted_at,
}) end)
{:noreply, socket} # :noreply
end
```
and at the top of the file update the `join` function to the following:
```elixir
def join("room:lobby", payload, socket) do
if authorized?(payload) do
send(self(), :after_join)
{:ok, socket}
else
{:error, %{reason: "unauthorized"}}
end
end
```
> _**Note**: like section 7, Phoenix knows to call this function when the server
> sends the internal message `:after_join` via the channel process._
>
> _Our `join/3` function in `lib/chat_web/channels/room_channel.ex` sends
> that `:after_join message` to the channel process when the client successfully
> connects to the `"room:lobby"` topic._
## 10. _Checkpoint_: Our Chat App Saves Messages!! (_Try it_!)
Start the Phoenix server (_if it is not already running_):
```sh
mix phx.server
```
> _**Note**: it will take a few seconds to **compile**_.
In your terminal, you should see:
```sh
[info] Running ChatWeb.Endpoint with cowboy 2.8.0 at 0.0.0.0:4000 (http)
[info] Access ChatWeb.Endpoint at http://localhost:4000
webpack is watching the filesβ¦
```
This tells us that our code compiled (_as expected_) and the Chat App
is running on TCP Port `4000`!
**Open** the Chat web app in
**two _separate_ browser windows**: http://localhost:4000
(_if your machine only has one browser try using one "incognito" tab_)
You should be able to send messages between the two browser windows:
Congratulations! You have a _working_ (_basic_) Chat App written in Phoenix!
The chat (message) history is _saved_!
This means you can _refresh_ the browser
_or_ join in a different browser and you will still see the history!
# Testing our App (_Automated Testing_)
Automated testing is one of the _best_ ways to ensure _reliability_
in your web applications.
> _**Note**: If you are completely new to Automated Testing
or "Test Driven Development" ("TDD"),
we recommend reading/following the "basic" tutorial:_
[github.com/dwyl/**learn-tdd**](https://github.com/dwyl/learn-tdd)
Testing in Phoenix is fast (_tests run in parallel!_)
and easy to get started!
The `ExUnit` testing framework is _built-in_
so there aren't an "decisions/debates"
about which framework or style to use.
If you have never seen or written a test with `ExUnit`,
don't fear, the syntax should be _familiar_ if you have
written _any_ sort of automated test in the past.
## 11. Run the Default/Generated Tests
Whenever you create a new Phoenix app
or add a new feature (_like a channel_),
Phoenix _generates_ a new test for you.
We _run_ the tests using the **`mix test`** command:
```elixir
........
Finished in 0.1 seconds (0.05s async, 0.06s sync)
8 tests, 0 failures
Randomized with seed 157426
```
In this case _none_ of these tests fails. (_8 tests, **0 failure**_)
## 12. Understanding The Channel Tests
It's worth taking a moment (_or as long as you need_!)
to _understand_ what is going on in the
[`/room_channel_test.exs`](/test/chat_web/channels/room_channel_test.exs)
file. _Open_ it if you have not already, read the test descriptions & code.
> For a bit of _context_ we recommend reading:
[https://hexdocs.pm/phoenix/**testing_channels**.html](https://hexdocs.pm/phoenix/testing_channels.html)
### 12.1 _Analyse_ a Test
Let's take a look at the _first_ test in
[/test/chat_web/channels/room_channel_test.exs](/test/chat_web/channels/room_channel_test.exs#L14-L17):
```elixir
test "ping replies with status ok", %{socket: socket} do
ref = push socket, "ping", %{"hello" => "there"}
assert_reply ref, :ok, %{"hello" => "there"}
end
```
The test gets the `socket` from the `setup` function (_on line 6 of the file_)
and assigns the result of calling the `push` function to a variable `ref`
`push` merely _pushes_ a message (_the map `%{"hello" => "there"}`_)
on the `socket` to the `"ping"` ***topic***.
The [`handle_in`](https://github.com/nelsonic/phoenix-chat-example/blob/f3823e64d9f9826db67f5cdf228ea5c974ad59fa/lib/chat_web/channels/room_channel.ex#L12-L16)
function clause which handles the `"ping"` topic:
```elixir
def handle_in("ping", payload, socket) do
{:reply, {:ok, payload}, socket}
end
```
Simply _replies_ with the payload you send it,
therefore in our _test_ we can use the `assert_reply` Macro
to assert that the `ref` is equal to `:ok, %{"hello" => "there"}`
> _**Note**: if you have questions or need **any** help
understanding the other tests, please open an issue on GitHub
we are happy to expand this further!_
(_we are just trying to keep this tutorial reasonably "brief"
so beginners are not "overwhelmed" by anything...)_
## 13. What is _Not_ Tested?
_Often_ we can learn a _lot_ about an application (_or API_)
from reading the tests and seeing where the "gaps" in testing are.
_Thankfully_ we can achieve this with only a couple of steps:
### 13.1 Add `excoveralls` as a (Development) Dependency to `mix.exs`
Open your `mix.exs` file and find the "deps" function:
```elixir
defp deps do
```
Add a comma to the end of the last line, then add the following line to the end
of the List:
```elixir
{:excoveralls, "~> 0.15.2", only: [:test, :dev]} # tracking test coverage
```
Additionally, find the `def project do` section (_towards the top of `mix.exs`_)
and add the following lines to the List:
```elixir
test_coverage: [tool: ExCoveralls],
preferred_cli_env: [
coveralls: :test,
"coveralls.detail": :test,
"coveralls.post": :test,
"coveralls.html": :test
]
```
_Then_, ***install*** the dependency on `excoveralls`
we just added to `mix.exs`:
```sh
mix deps.get
```
You should see:
```sh
Resolving Hex dependencies...
Dependency resolution completed:
* Getting excoveralls (Hex package)
... etc.
```
### 13.2 Create a _New File_ Called `coveralls.json`
In the "root" (_base directory_) of the Chat project,
create a new file called `coveralls.json` and _copy-paste_ the following:
```json
{
"coverage_options": {
"minimum_coverage": 100
},
"skip_files": [
"test/",
"lib/chat/application.ex",
"lib/chat_web.ex",
"lib/chat_web/telemetry.ex",
"lib/chat_web/components/core_components.ex",
"lib/chat_web/channels/user_socket.ex"
]
}
```
This file is quite basic, it instructs the `coveralls` app
to require a **`minimum_coverage`** of **100%**
(_i.e. **everything is tested**1_)
and to _ignore_ the files in the `test/` directory for coverage checking.
We also ignore files such as `application.ex`,
`telemetry.ex`, `core_components.ex` and `user_socket.ex`
because they are not relevant for the functionality of our project.
> _1We believe that **investing**
a little **time up-front** to write tests for **all** our **code**
is **worth it** to have **fewer bugs** later.
**Bugs** are **expensive**, **tests** are **cheap**
and **confidence**/**reliability** is **priceless**_.
### 13.3 Run the Tests with Coverage Checking
To run the tests with coverage, copy-paste the following command
into your terminal:
```elixir
MIX_ENV=test mix do coveralls.json
```
> For windows use:
> ```elixir
> $env:MIX_ENV="test"; mix do coveralls.json
> ```
You should see:
```
Randomized with seed 527109
----------------
COV FILE LINES RELEVANT MISSED
100.0% lib/chat.ex 9 0 0
100.0% lib/chat/message.ex 26 4 0
100.0% lib/chat/repo.ex 5 0 0
70.0% lib/chat_web/channels/room_channel.ex 46 10 3
100.0% lib/chat_web/components/layouts.ex 5 0 0
100.0% lib/chat_web/controllers/error_html.ex 19 1 0
100.0% lib/chat_web/controllers/error_json.ex 15 1 0
100.0% lib/chat_web/controllers/page_controller 9 1 0
100.0% lib/chat_web/controllers/page_html.ex 5 0 0
100.0% lib/chat_web/endpoint.ex 49 0 0
66.7% lib/chat_web/router.ex 27 3 1
[TOTAL] 80.0%
----------------
```
As we can se here, only **80%** of lines of code in `/lib`
are being "covered" by the tests we have written.
To **view** the coverage in a web browser run the following:
```elixir
MIX_ENV=test mix coveralls.html ; open cover/excoveralls.html
```
This will open the Coverage Report (HTML) in your default Web Browser:
### 13.4 Write a Test for the Untested Function
Open the `test/chat_web/channels/room_channel_test.exs` file
and add the following test:
```elixir
test ":after_join sends all existing messages", %{socket: socket} do
# insert a new message to send in the :after_join
payload = %{name: "Alex", message: "test"}
Chat.Message.changeset(%Chat.Message{}, payload) |> Chat.Repo.insert()
{:ok, _, socket2} = ChatWeb.UserSocket
|> socket("person_id", %{some: :assign})
|> subscribe_and_join(ChatWeb.RoomChannel, "room:lobby")
assert socket2.join_ref != socket.join_ref
end
```
Finally, inside `lib/chat_web/router.ex`,
comment the following piece of code.
```elixir
pipeline :api do
plug :accepts, ["json"]
end
```
Since we are not using this `:api` in this project,
there is no need to test it.
Now when you run `MIX_ENV=test mix do coveralls.json`
you should see:
```
Randomized with seed 15920
----------------
COV FILE LINES RELEVANT MISSED
100.0% lib/chat.ex 9 0 0
100.0% lib/chat/message.ex 26 4 0
100.0% lib/chat/repo.ex 5 0 0
100.0% lib/chat_web/channels/room_channel.ex 46 10 0
100.0% lib/chat_web/components/layouts.ex 5 0 0
100.0% lib/chat_web/controllers/error_html.ex 19 1 0
100.0% lib/chat_web/controllers/error_json.ex 15 1 0
100.0% lib/chat_web/controllers/page_controller 9 1 0
100.0% lib/chat_web/controllers/page_html.ex 5 0 0
100.0% lib/chat_web/endpoint.ex 49 0 0
100.0% lib/chat_web/router.ex 27 2 0
[TOTAL] 100.0%
----------------
```
This test just creates a message before
the `subscribe_and_join` so there is a message in the database
to send out to any client that joins the chat.
That way the `:after_join` has at least one message
and the `Enum.each` will be invoked at least once.
With that our app is fully tested!
# Authentication
We can *extend* this project
to support basic authentication.
If you want to _understand_
how Authentication is implemented the _easy/fast_ way,
see:
[auth.md](https://github.com/dwyl/phoenix-chat-example/blob/main/auth.md)
# Adding `Presence` to track who's online
One of the great advantages
of using `Phoenix`
is that you can
*easily track processes*
and channels.
This paves the way to *effortlessly*
showing who's online or not!
If you are interested in
developing this feature,
we have created a guide in
[`presence.md`](./presence.md)
just for you! π
# Continuous Integration
Continuous integration
lets you _automate_ running the tests
to check/confirm that your app
is working as _expected_ (_before deploying_).
This prevents accidentally "_breaking_" your app.
_Thankfully_ the steps are quite simple.
For an example `ci.yml`, see:
[`.github/workflows/ci.yml`](https://github.com/dwyl/phoenix-chat-example/blob/main/.github/workflows/ci.yml)
# Deployment!
Deployment to Fly.io takes a couple of minutes,
we recommend following the official guide:
[fly.io/docs/elixir/**getting-started**](https://fly.io/docs/elixir/getting-started/)
Once you have _deployed_ you will will be able
to view/use your app in any Web/Mobile Browser.
e.g:
[**phoenix-chat**.fly.dev/](https://phoenix-chat.fly.dev/)
## What _Next_?
If you found this example useful, please βοΈ the GitHub repository
so we (_and others_) know you liked it!
If you want to learn more Phoenix and the magic of **`LiveView`**,
consider reading our beginner's tutorial:
[github.com/dwyl/**phoenix-liveview-counter-tutorial**](https://github.com/dwyl/phoenix-liveview-counter-tutorial)
For a version of a chat application using **LiveView** you can read the following repository:
[github.com/dwyl/**phoenix-liveview-chat-example**](https://github.com/dwyl/phoenix-liveview-chat-example)
Thank you for learning with us! βοΈ
## Inspiration
This repo is inspired by @chrismccord's Simple Chat Example:
https://github.com/chrismccord/phoenix_chat_example β€οΈ
At the time of writing Chris' example was last updated on
[20 Feb 2018](https://github.com/chrismccord/phoenix_chat_example/commit/7fb1d3d040b9d1e9a1bbd239c60ca1f4dd403c24)
and uses
[Phoenix 1.3](https://github.com/chrismccord/phoenix_chat_example/blob/7fb1d3d040b9d1e9a1bbd239c60ca1f4dd403c24/mix.exs#L25)
see:
[issues/40](https://github.com/chrismccord/phoenix_chat_example/issues/40).
There are quite a few differences (breaking changes)
between Phoenix 1.3 and 1.6 (_the latest version_).
Our tutorial uses Phoenix `1.6.2` (latest as of October 2021).
Our hope is that by writing (_and maintaining_)
a step-by-step beginner focussed
tutorial we contribute to the Elixir/Phoenix community
without piling up
[PRs](https://github.com/chrismccord/phoenix_chat_example/pulls)
on Chris's repo.
## Recommended Reading / Learning
+ ExUnit docs: https://hexdocs.pm/ex_unit/ExUnit.html
+ Testing Phoenix Channels:
https://quickleft.com/blog/testing-phoenix-websockets
+ Phoenix WebSockets Under a Microscope:
https://zorbash.com/post/phoenix-websockets-under-a-microscope
With this done, we can proceed.