README.md

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### See [Demo Page](https://tg.pl/drab) for live demo and description.

Drab - Access the browser User Interface from the Server Side. No Javascript programming needed anymore!

Drab extends Phoenix Framework to "remote control" UI on the browser, live. The idea is to move all User Interface
logic to the server-side, to eliminate Javascript and Ajax calls.

## Teaser

* Client side:

```html
<div class="progress">
  <div class="progress-bar <%= @progress_bar_class %>" role="progressbar" @style.width=<%= "#{@bar_width}%" %>>
    <%= "#{@bar_width}%" %>
  </div>
</div>
<button class="btn btn-primary" drab-click="perform_long_process">
  <%= @long_process_button_text %>
</button>
```

* Server side:

```elixir
defhandler perform_long_process(socket, _sender) do
  poke socket, progress_bar_class: "progress-bar-danger", long_process_button_text: "Processing..."

  steps = :rand.uniform(100)
  for i <- 1..steps do
    Process.sleep(:rand.uniform(500)) #simulate real work
    poke socket, bar_width: Float.round(i * 100 / steps, 2)
  end

  poke socket, progress_bar_class: "progress-bar-success", long_process_button_text: "Click me to restart"
end
```

## Prerequisites

  1. Elixir ~> 1.6.0 (see [Installation Guide](https://elixir-lang.org/install.html))

  2. Phoenix ~> 1.2 (see [Installation Guide](https://hexdocs.pm/phoenix/installation.html#phoenix))

## Browser Requirements

This has the same requirements as Phoenix.Sockets.  Above that it depends on the javascript you call or other potential tools you use on top of Drab.

## Installation

  First of all, you need to have a Phoenix application, on top of which you will install Drab. If this is a standard app, generated with `mix phx.new`, you may use Drab Installer to make it running in one, simple step. Otherwise, see [Manual Installation](#manual-installation) section below.

  1. Edit `mix.exs` in the main folder in your web application (if you have multiple application under an umbrella, this is the one ending with `_web`). Locate function `deps` (search for `def deps` string). Add an entry `{:drab, "~> 0.10.0"}` to the list. Don't forget about comma!

```elixir
def deps do
  [
    {...},
    {:drab, "~> 0.10.0"}
  ]
end
```

  2. Download and install packages:

```bash
$ mix deps.get
```

  3. Go to the application directory (**if your Phoenix Web application is under the umbrella, go there**) and run `mix drab.install`:

```
bash% mix drab.install
Checking prerequisites for :my_app
  lib/my_app_web/templates/layout/app.html.eex
  lib/my_app_web/channels/user_socket.ex
  config/config.exs
  config/dev.exs
The installer is going to modify those files. OK to proceed? [Yn] Y
Drab has been successfully installed in your Phoenix application.

Now it is time to create your first commander, for example, for PageController:

    mix drab.gen.commander Page
```

Congratulations! You have installed Drab and you can proceed with your own commander.

Please notice that Drab will run only on pages, which have the corresponding commander.

## Usage

All the Drab functions (callbacks, event handlers) are placed in the module called `Commander`.
Think about it as a controller for the live pages. Commanders should be placed in `web/commanders` directory.

To enable Drab on the pages generated with corresponding controller, you need to create a twin commander. For example, for `MyApp.PageController` the commander should be named `MyApp.PageCommander`.

Remember the difference: `controller` renders the page, while `commander` works on the live page.

  1. Generate the page Commander. The commander name should correspond to the controller, so `PageController` should have `PageCommander`:

```bash
$ mix drab.gen.commander Page
* creating web/commanders/page_commander.ex
```

  2. Add the `@welcome_text` assign to `render/3` in index action in the controller, to be used in the future:

```elixir
defmodule MyApp.PageController do
  use Example.Web, :controller

  def index(conn, _params) do
    render conn, "index.html", welcome_text: "Welcome to Phoenix!"
  end
end
```

  3. Rename the template from `web/templates/page/index.html.eex` to `index.html.drab`

  4. Edit the template `web/templates/page/index.html.drab` and change the fixed welcome text to the assign:

```html
<div class="jumbotron">
  <h2><%= @welcome_text %></h2>
```

  5. Edit the commander file `web/commanders/page_commander.ex` and add some real action - the `onload` callback, which fires when the browser connects to the Drab server:

```elixir
defmodule DrabExample.PageCommander do
  use Drab.Commander

  onload :page_loaded

  # Drab Callbacks
  def page_loaded(socket) do
    poke socket, welcome_text: "This page has been drabbed"
    set_prop socket, "div.jumbotron p.lead",
      innerHTML: "Please visit <a href='https://tg.pl/drab'>Drab</a> page for more"
  end
end
```

The `poke/2` function updates the assign. The `set_prop/3` updates any property of the DOM object. All is done live, without reloading the page.

  6. Run `iex -S mix phoenix.server`. Go to `http://localhost:4000` to see the changed web page. Now you may play with this page live, directly from `iex`! Observe the instruction given when your browser connects to the page:

```elixir
[debug]
    Started Drab for same_path:/, handling events in DrabExample.PageCommander
    You may debug Drab functions in IEx by copy/paste the following:
import Drab.{Core, Element, Live}
socket = Drab.get_socket(pid("0.653.0"))

    Examples:
socket |> exec_js("alert('hello from IEx!')")
socket |> poke(count: 42)

```

As instructed, copy and paste those two lines, and check out yourself how you could remotely control the displayed page:

```elixir
iex> alert socket, "Alert title", "Do you like modals?", buttons: [ok: "A juści", cancel: "Poniechaj"]
{:ok, %{}}

iex> poke socket, welcome_text: "WOW, this is nice"
%Phoenix.Socket{...}

iex> query socket, "div.jumbotron h2", :innerText
{:ok,
 %{"[drab-id='425d4f73-9c14-4189-992b-41539377c9eb']" => %{"innerText" => "WOW, this is nice"}}}

iex> set_style socket, "div.jumbotron", backgroundColor: "red"
{:ok, 1}
```


### The example above is available [here](https://github.com/grych/drab-example)

## What now?

Visit [Demo Page](https://tg.pl/drab) for a live demo and more description.

Visit [Documentation](https://hexdocs.pm/drab) page.

## Getting help

There is a Drab's thread on [elixirforum.com](https://elixirforum.com/t/drab-phoenix-library-for-server-side-dom-access/3277), please address questions there.

## Tests and Sandbox

Since 0.3.2, Drab is equipped with its own Phoenix Server for running integration tests automatically, for sandboxing and for  playing
with it.

### Sandbox

* clone Drab from github:

```shell
git clone git@github.com:grych/drab.git
cd drab
```

* get deps and node modules:

```shell
mix deps.get
npm install && node_modules/brunch/bin/brunch build
```

* start Phoenix with Drab:

```shell
iex -S mix phoenix.server
```

* open the browser and navigate to http://localhost:4000

* follow the instructions in IEx to play with Drab functions:

```elixir
import Drab.{Core, Live, Element, Query, Waiter}
socket = Drab.get_socket(pid("0.784.0"))

iex> query socket, "h3", :innerText
{:ok,
 %{"#header" => %{"innerText" => "Drab Tests"},
   "#page_loaded_indicator" => %{"innerText" => "Page Loaded"}}}

iex> set_prop socket, "h3", innerText: "Updated from IEx"
{:ok, 2}

iex> exec_js socket, "alert('You do like alerts?')"
{:ok, nil}
```

### Tests

Most of the Drab tests are integration (end-to-end) tests, thus they require automated browser. Drab uses [chromedriver](https://sites.google.com/a/chromium.org/chromedriver/), which must be running while you run tests.

* clone Drab from github:

```shell
git clone git@github.com:grych/drab.git
cd drab
```

* get deps and node modules:

```shell
mix deps.get
npm install && node_modules/brunch/bin/brunch build
```

* run `chromedriver`

* run tests:

```shell
% mix test
Compiling 23 files (.ex)
........................................

Finished in 120.9 seconds
123 tests, 0 failures

Randomized with seed 934572
```

## Manual Installation

  1. Add Drab to the dependencies in `mix.exs`.

  2. Initialize Drab client library by adding to the layout page (`app.html.eex` - or any other layout you use).

```html
<%= Drab.Client.run(@conn) %>
```

  just after the following line:

```html
<script src="<%= static_path(@conn, "/js/app.js") %>"></script>
```

  3. Initialize Drab sockets by adding the following to `user_socket.ex`:

```elixir
use Drab.Socket
```

  4. Add Drab template engine and application name with endpoint to `config.exs`:

```elixir
config :phoenix, :template_engines,
  drab: Drab.Live.Engine

config :drab, MyAppWeb.Endpoint,
  otp_app: :my_app_web
```

  5. Add `:drab` to applications started by default in `mix.exs`:

```elixir
def application do
  [mod: {MyApp, []},
   applications: [:phoenix, :phoenix_pubsub, :phoenix_html, :cowboy, :logger, :gettext, :drab]]
end
```

  It is not needed if you are running Phoenix 1.3

  6. To enable live reload on Drab pages, add `.drab` extension to live reload patterns in `dev.exs`:

```elixir
config :my_app, MyApp.Endpoint,
  live_reload: [
    patterns: [
      ~r{priv/static/.*(js|css|png|jpeg|jpg|gif|svg)$},
      ~r{priv/gettext/.*(po)$},
      ~r{web/views/.*(ex)$},
      ~r{web/templates/.*(eex|drab)$}
    ]
  ]
```

  7. If you are not using webpack, you will get `require is not defined` error. You need to provide `Socket`:

  In the `app.js` add a global variable, which will be passed to Drab later:

```elixir
  window.__socket = require("phoenix").Socket;
```

  Then, tell Drab to use this instead of default `require("phoenix").Socket`. Add to `config.exs`:

```elixir
config :drab, MyAppWeb.Endpoint,
  js_socket_constructor: "window.__socket"
```


#### If you want to use Drab.Query (jQuery based module):

  1. Add `jquery` and `boostrap` to `package.json`:

```json
"dependencies": {
  "jquery": ">= 3.1.1",
  "bootstrap": "~3.3.7"
}
```

  2. Add jQuery as a global at the end of `brunch-config.js`:

```javascript
npm: {globals: {
  $: 'jquery',
  jQuery: 'jquery',
  bootstrap: 'bootstrap'
}}
```

  3. And install it:

```bash
$ npm install && node_modules/brunch/bin/brunch build
```

## Contact

(c)2016-2018 Tomek "Grych" Gryszkiewicz,
<grych@tg.pl>


Illustrations by https://www.vecteezy.com