* Home
:PROPERTIES:
:ONE: one-custom-default-home
:CUSTOM_ID: /
:TITLE:
:DESCRIPTION: Framework for creating Realtime SPAs using HTML over the Wire technology.
:NAVIGATOR-ACTIVE: home
:END:

** What is HTML over the Wire?

HTML over ther Wire, or HTML over the WebSockets, is a strategy for creating real-time SPAs by creating a WebSockets connection between a client and a server. It allows JavaScript to request actions, its only responsibility is to handle events, and the backend handles the business logic as well as rendering HTML. This means you can create pages without reloading the page, without AJAX or APIs. One technology provides a secure, stable and low-delay connection for real-time web applications.

#+ATTR_HTML: :class center-block image image--home
[[#/img/step-1.avif][Architecture send]]

#+ATTR_HTML: :class center-block image image--home
[[#/img/step-2.avif][Architecture receive]]

** What is Django LiveView?

Django LiveView is a framework for creating Realtime SPAs using HTML over the Wire technology. It is inspired by Phoenix LiveView and it is built on top of Django Channels.

It allows you to create interactive web applications using only HTML, CSS and Python. JavaScript ONLY is used to capture events, send and receive strings over a WebSockets channel.

Let's illustrate with an example. I want to print article number 2.

1- A WebSockets connection, a channel, is established between the client and the server.

2- JavaScript sends a text, not a request, via WebSockets to the Server (in our case Django).

#+ATTR_HTML: :class center-block image image--home
[[#/img/step-3.avif][Send string]]

3- Django interprets the text and renders the HTML of the article through the template system and the database.

4- Django sends the HTML to JavaScript via the channel and tells it which selector to embed it in.

#+ATTR_HTML: :class center-block image image--home
[[#/img/step-4.avif][Send JSON]]

5- JavaScript draws the received HTML in the indicated selector.

#+ATTR_HTML: :class center-block image image--home
[[#/img/step-5.avif][Place HTML]]

The same process is repeated for each action, such as clicking a button, submitting a form, etc.

** What are your superpowers?

- All in real time. The data is sent and received instantly.
- Single connection. You don't need to open and close connections like calls to an API.
- Create SPAs without using APIs o JavaScript frameworks.
- Uses Django's template system to render the frontend (The use of JavaScript is anecdotal).
- The logic is not split between the backend and the frontend, it all stays in Python.
- You can still use all of Django's native tools, such as its ORM, forms, plugins, etc.
- Everything is asynchronous by default.
- Don't learn anything new. If you know Python, you know how to use Django LiveView.

Are you ready to create your first Realtime SPA? Let's go to the [[#/tutorials/quickstart/][Quickstart]].

* Install
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/install/
:TITLE: Install
:DESCRIPTION: Install Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

You can install Django LiveView with ~pip~.

#+BEGIN_SRC sh
pip install django-liveview
#+END_SRC

Then add ~liveview~ to your installed ~INSTALLED_APPS~ in your ~settings.py~.

#+BEGIN_SRC python
INSTALLED_APPS = [
    "daphne",
    "channels",
    "liveview",
]
#+END_SRC

You need to previously have installed ~channels~ and ~daphne~.

Now, in ~settings.py~, indicate in which previously created App you want to integrate LiveView.

#+BEGIN_SRC python
LIVEVIEW_APPS = ["website"]
#+END_SRC

Finally, execute the migrations so that the LiveView tables are generated.

#+BEGIN_SRC python
python manage.py migrate
#+END_SRC

We strongly recommend that you follow the [[#/tutorials/quickstart/][Quickstart]] to see the installation in action.

* Actions
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/actions/
:TITLE: Actions
:DESCRIPTION: Actions of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

Actions are where business logic is stored. The place where you write the functions in Python instead of JavaScript. They are the ones that will be executed when the page is loaded, when a button is clicked, when a form is submitted, etc. The can be launched by the backend or by the frontend. For example, when a button is clicked, the frontend sends a request to the backend to execute an action. But the backend can send a request to the frontend at any time, for example when a new commentary is added to an article then all clients will receive the new commentary. In other words, the actions can be executed by the backend or by the frontend.  The more common actions will be render HTML and send it to the client, but you can do anything you want. They are the heart of Django LiveView.

** Backend side

In every app you can create a folder called ~actions~ and inside it a file for each page. For example, ~home.py~ for the home page. The file will have the following structure:

#+BEGIN_SRC python
  # my_app/actions/home.py
  from liveview.context_processors import get_global_context
  from core import settings
  from liveview.utils import (
      get_html,
      update_active_nav,
      enable_lang,
      loading,
  )
  from django.utils.translation import gettext as _
  from django.templatetags.static import static
  from django.urls import reverse

  template = "pages/home.html"

  # Database

  # Functions

  async def get_context(consumer=None):
      context = get_global_context(consumer=consumer)
      # Update context
      context.update(
	  {
	      "url": settings.DOMAIN_URL + reverse("home"),
	      "title": _("Home") + " | Home",
	      "meta": {
		  "description": _("Home page of the website"),
		  "image": f"{settings.DOMAIN_URL}{static('img/seo/og-image.jpg')}",
	      },
	      "active_nav": "home",
	      "page": template,
	  }
      )
      return context


  @enable_lang
  @loading
  async def send_page(consumer, client_data, lang=None):
      # Nav
      await update_active_nav(consumer, "home")
      # Main
      my_context = await get_context(consumer=consumer)
      html = await get_html(template, my_context)
      data = {
	  "action": client_data["action"],
	  "selector": "#main",
	  "html": html,
      }
      data.update(my_context)
      await consumer.send_html(data)
#+END_SRC

Let's explain each part.

- ~template~ is the name of the template that will be rendered.
- ~get_context()~ is a function that returns a dictionary with the context of the page.
  - ~url~: The URL of the page. It will be used to change the direction of the browser and the user perceives a page change, even if it is not real.
  - ~title~: The title of the page.
  - ~meta~: They are the SEO and Open Graph meta tags.
- ~active_nav~: It is used to highlight the active page in the navigation menu.
- ~page~: Name of the template that will be rendered. it is the same as ~template~.

The function ~send_page()~ is responsible for rendering the page and sending it.

#+BEGIN_SRC python

from liveview.utils import (
    get_html,
    update_active_nav,
    enable_lang,
    loading,
)

@enable_lang
@loading
async def send_page(consumer, client_data, lang=None):
    # Nav
    await update_active_nav(consumer, "home")
    # Main
    my_context = await get_context(consumer=consumer)
    html = await get_html(template, my_context)
    data = {
	"action": client_data["action"],
	"selector": "#main",
	"html": html,
    }
    data.update(my_context)
    await consumer.send_html(data)
#+END_SRC

~update_active_nav()~ updates the class that marks the page where we are in the menu. You need update the context with the data that you want to send to the client. ~get_html()~ is a function that renders the template with the context. ~send_html()~ is a function that sends the HTML to the client.

Whenever you want to send a new HTML to the frontend, you will use the ~send_html()~ function with the following structure.

#+BEGIN_SRC python
data = {
    "action": "home->send_page",
    "selector": "#main",
    "html": "<h1>My home</h1><p>Welcome to my home</p>",
}
await consumer.send_html(data)
#+END_SRC

- ~action~: The name of the action that will be executed on the client side. It is used for cache management and to know which action to execute. It will almost always be the same action that the client sent us.
- ~selector~: The selector where the HTML will be placed.
- ~html~: The HTML that will be placed in the selector.

Optionally we can include others.

- ~append~: Default: false. If true, the HTML will be added, not replaced.
- ~delete~: Default: false. If true, the HTML will be deleted. ~html~ and ~append~ will be ignored. Only ~selector~ will be used.
- ~scroll~: Default: false. If true, the page will be scrolled to the selector
- ~scrollTop~: Default: false. If true, the page will be scrolled to the top.

When you update via context, you add the following. They are all optional.

- ~title~: The title of the page.
- ~meta~: They are the SEO and Open Graph meta tags.
- ~active_nav~: It is used to highlight the active page in the navigation menu.
- ~page~: Name of the template that will be rendered.

*** Decorators

You can use the following decorators to make your actions more readable and maintainable.

- ~@enable_lang~: It is used to enable the language. It is necessary to use the ~gettext~ function. If you site only has one language, you can remove it.
- ~@loading~: It is used to show a loading animation while the page is being rendered. If there is no loading delay, for example the database access is very fast or you don't access anything external like an API, you can remove it.

*** Database access (ORM)

If you want to access the database, you can use the Django ORM as you would in a normal view. The only difference is that the views are asynchronous by default. You can use the ~database_sync_to_async~ function from ~channels.db~.

#+BEGIN_SRC python
  from channels.db import database_sync_to_async
  from .models import Article

  template = "pages/articles.html"

  # Database
  @database_sync_to_async
  def get_articles(): # New
      return Article.objects.all()

  # Functions

  async def get_context(consumer=None):
      articles = await get_articles()
      context = get_global_context(consumer=consumer)
      # Update context
      context.update(
	  {
	      ...
	      "articles": await get_articles(), # New
	  }
      )
      return context

#+END_SRC

Now you can use the ~articles~ variable in the template.

#+BEGIN_SRC html
{% for article in articles %}
    <h2>{{ article.title }}</h2>
    <p>{{ article.content }}</p>
{% endfor %}
#+END_SRC

If you want the SSR (Server Side Rendering) to continue working, you need to modify the view function so that it is asynchronous.

From:

#+BEGIN_SRC python
  async def articles(request):
      return render(request, settings.TEMPLATE_BASE, await get_context())
#+END_SRC

To:

#+BEGIN_SRC python
  from asgiref.sync import sync_to_async

  async def articles(request):
      return await sync_to_async(render)(request, settings.TEMPLATE_BASE, await get_context())
#+END_SRC

** Frontend side

The frontend is responsible for capturing events and sending and receiving strings. No logic, rendering or state is in the frontend. It is the backend that does all the work.

Since DOM trees are constantly being created, updated and deleted, a small framework is used to manage events and avoid collisions: [[https://stimulus.hotwired.dev/][Stimulus]]. It is very simple and easy to use. In addition, some custom functions have been created to simplify more processes such as WebSockets connection, data sending, painting, history, etc. When you cloned the [[https://github.com/Django-LiveView/frontend][frontend]] repository you included all of that. You do not have to do anything.

*** Run actions

In the following example, we will create a button that when clicked will call the ~sent_articles_next_page~ function of the ~blog_list~ action (~actions/blog_list.py~).

#+BEGIN_SRC html
<button type="button"
    data-action="click->page#run"
    data-liveview-action="blog_list"
    data-liveview-function="send_articles_next_page"
    data-next-page="2"
>Cargar mas</button>
#+END_SRC

- ~data-action~: Required. Indicate the event (~click~), the controller (~page~ is the default controller in Django LiveView) and function in Stimulus (~run~). You will never change it.
- ~data-liveview-action~: Required. The name of the action file (~blog_list.py~).
- ~data-liveview-function~: Required. The name of the function in the action file (~send_articles_next_page~).
- ~data-next-page~: Optional. You can send data to the backend. In this case, the page number.

*** Change page

All actions have a mandatory function ~send_page~. It is used to move from one page to another. There is a quick function called ~changePage~ to do this.

For example, if you want to go to the About Me page, you can use the following code.

#+BEGIN_SRC html
<button
    data-action="click->page#changePage"
    data-page="about_me"
   >Go to about me page</button>
#+END_SRC

It would be equivalent to doing:

#+BEGIN_SRC html
<button
    data-action="click->page#run"
    data-liveview-action="about_me"
    data-liveview-function="send_page"
   >Go to about me page</button>
#+END_SRC

* Views
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/views/
:TITLE: Views
:DESCRIPTION: Views of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

Django LiveView uses the same views as Django, but the main difference is that the views are asynchronous by default.

To make a view renderable by SSR (Server Side Rendering) and by SPA (Single Page Application), you need to create a function with the following structure:

#+BEGIN_SRC python
  from .actions.home import get_context as get_home_context

  async def home(request):
      return render(request, settings.TEMPLATE_BASE, await get_home_context())
#+END_SRC

The ~get_home_context()~ function returns a dictionary with the context of the page present in the action. The ~settings.TEMPLATE_BASE~ is the base template that will be rendered, por example ~layouts/base.html~.

If you want to render data from a database on the template, for example:

#+BEGIN_SRC html
{% for article in articles %}
    {{ article.title }}
    {{ article.content }}
{% endfor %}
#+END_SRC

You will see an error: ~You cannot call this from an async context - use a thread or sync_to_async.~.

You can use the ~sync_to_async~ function from ~asgiref~.

#+BEGIN_SRC python
  from asgiref.sync import sync_to_async
  from .actions.blog_list import get_context as get_list_context

  async def blog_list(request):
      return await sync_to_async(render)(request, settings.TEMPLATE_BASE, await get_list_context())
#+END_SRC

Or transform ~articles~ to a list. But you lose the benefits of ORM.

* Routing
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/routing/
:TITLE: Routing
:DESCRIPTION: Routing of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

If you want to move from one page to another, you can use the ~page~ controller and the ~changePage~ action.

For example, you can create a link to the ~about me~ page.

#+BEGIN_SRC html
  <a
      data-action="click->page#changePage"
      data-page="about_me"
      href="{% url "about me" %}" <!-- Optional -->
      role="button" <!-- Optional -->
     >Go to about me page</a>
#+END_SRC

- ~data-action~: Indicates that the element is an action. ~click~ to capture the click event. ~page#changePage~ to call the ~changePage~ function of the ~page~ controller.
- ~data-page~: Indicates the name of the page to which you want to move. The name is the same as the name of the action file. For example, ~actions/about_me.py~.
- ~href~: Optional. It is recommended to use the ~href~ attribute to improve SEO or if JavaScript is disabled.
- ~role~: Optional. It is recommended to use the ~role~ attribute to improve accessibility or if JavaScript is disabled.

Or use a button for it.

#+BEGIN_SRC html
  <button
      data-action="click->page#changePage"
      data-page="about_me"
     >Go to about me page</button>
#+END_SRC

** Send data

If you want to send data to the next page, you can use the ~data-~ attribute. All datasets will be sent.

For example, you can create a link to the ~blog single~ page with the ~slug~ of the article.

#+BEGIN_SRC html
  <a
      data-action="click->page#changePage"
      data-page="blog_single"
      data-slug="{{ article.slug }}"
      href="{% url "blog single" slug=article.slug %}" <!-- Optional -->
      role="button" <!-- Optional -->
     >See article</a>
#+END_SRC

To receive the data in action ~blog_single.py~ you can use the ~client_data~ parameter with the ~data~ key.

#+BEGIN_SRC python
    @enable_lang
    @loading
    async def send_page(consumer, client_data, lang=None):
	slug = client_data["data"]["slug"]
	# ...
#+END_SRC

Here you can see a typical example of a single page of a blog.

#+BEGIN_SRC python
  @enable_lang
  @loading
  async def send_page(consumer, client_data, lang=None):
      # Nav
      await update_active_nav(consumer, "blog")
      # Main
      my_context = await get_context(consumer=consumer, slug=client_data["data"]["slug"])
      html = await get_html(template, my_context)
      data = {
	  "action": client_data["action"],
	  "selector": "#main",
	  "html": html,
      }
      data.update(my_context)
      await consumer.send_html(data)
#+END_SRC

* Forms
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/forms/
:TITLE: Forms
:DESCRIPTION: Forms of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

Los formularios en Django LiveView son nativos de Django. Puedes usar los formularios de modelo, los formularios de clase, los formularios de funciones, etc. O crearlos directamente en HTML. La única diferencia es que los datos se envían a través de WebSockets en lugar de HTTP.

** Recoger un campo

A continución puedes ver un ejemplo de un formulario de búsqueda donde se crea un campo de texto.

#+BEGIN_SRC python
from django import forms

class SearchForm(forms.Form):
    search = forms.CharField(
        label="Search",
        max_length=255,
        widget=forms.TextInput(
            attrs={
                "data-action": "keyup.enter->page#run",
                "data-liveview-action": "blog_list",
                "data-liveview-function": "send_search_results",
            },
        ),
    )
#+END_SRC

Cuando se pulse la tecla ~Enter~ se ejecutará la función ~send_search_results~ del archivo de acción ~blog_list.py~.

Incluyelo en el contexto.

#+BEGIN_SRC python
  async def get_context(consumer=None):
      context = get_global_context(consumer=consumer)
      # Update context
      context.update(
	  {
	      ...
	      "search_form": SearchForm(),
	      ...
	  }
      )
      return context
#+END_SRC

E imprimirlo en el template puedes hacerlo mediante el objeto.

  #+BEGIN_SRC html
  <form id="search" class="search">
      {{ search_form.as_p }}
  </form>
#+END_SRC

Para recoger los datos en la función ~send_search_results~ puedes hacerlo mediante el objeto ~client_data~.

#+BEGIN_SRC python
  @enable_lang
  @loading
  async def send_search_results(consumer, client_data, lang=None):
      search = client_data["form"]["search"]
      # ...
#+END_SRC

** Recoger un formulario completo

Recibir un campo o todo un formulario es similar. La diferencia es que ~action~, ~data-liveview-action~ y ~data-liveview-function~ se encuentran en el formulario, o botón de envío, y no en un campo concreto.

Veamos un ejemplo de un formulario de contacto.

#+BEGIN_SRC python
  class ContactForm(forms.Form):
      name = forms.CharField(
	  label="Name",
	  max_length=255,
      )
      email = forms.EmailField(
	  label="Email",
	  max_length=255,
      )
      message = forms.CharField(
	  label="Message",
      )

#+END_SRC

Lo incluimos en el contexto.

#+BEGIN_SRC python
  async def get_context(consumer=None):
      context = get_global_context(consumer=consumer)
      # Update context
      context.update(
	  {
	      ...
	      "contact_form": ContactForm(),
	      ...
	  }
      )
      return context
#+END_SRC

Y lo imprimimos en el template con el botón de envío personalizado.

#+BEGIN_SRC html
  <form id="contact" class="contact">
      {{ contact_form.as_p }}
      <button
	  type="button"
	  data-action="click->page#run"
	  data-liveview-action="contact"
	  data-liveview-function="send_contact"
      >Send</button>
  </form>
#+END_SRC

Los datos se recogen de la misma forma que en el caso anterior.

#+BEGIN_SRC python
  @enable_lang
  @loading
  async def send_contact(consumer, client_data, lang=None):
      name = client_data["form"]["name"]
      email = client_data["form"]["email"]
      message = client_data["form"]["message"]
      # ...
#+END_SRC

** Validaciones y errores

Para validar un formulario puedes hacerlo de la misma forma que en Django. Pero si quieres mostrar los errores en tiempo real, debes redibujar el formulario en cada ocasión.

* History
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/history/
:TITLE: History
:DESCRIPTION: History management of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

If you make a SPA you will have a problem with the history management system. When you go back in history, you will lose the data and the HTML of the previous page. This is because the data is removed from the DOM. It is not a problem with Django LiveView.

Django LiveView has a history management system that allows you go back in history without receive any data from the server. Every time you change the page, the data and HTML are stored in the Session Storage. You don't need to do anything, it is automatic! 😸

The only limitation is forward navigation. If you want to go forward, you need to receive the data from the server because the data is remove from the Session Storage when you go back.

You can customize the history management system by editing the ~history~ controller in ~assets/js/mixins/history.js~.

If you want to disable it, remove `startHistory();` from ~assets/js/main.js~.

* Internationalization
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/internationalization/
:TITLE: Internationalization
:DESCRIPTION: Internationalization of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

Django LiveView uses the same internationalization system as Django. You can read more about it in the [[https://docs.djangoproject.com/en/dev/topics/i18n/][Django documentation]]. However, let's go deeper.

Every time that the client sends a request for action, it sends the language that the user has set in the browser.

#+BEGIN_SRC json
  {
  "action": "blog_list->send_page",
  "data": {
    "lang": "es"
  }
}
#+END_SRC

The ~lang~ attribute is extracted directly from the ~<html>~ tag.

#+BEGIN_SRC html
    {% load static i18n %}
  <!doctype html>{% get_current_language as CURRENT_LANGUAGE %}
  <html lang="{{ CURRENT_LANGUAGE }}">
#+END_SRC

You can access the language with the ~lang~ parameter of the action using the ~@enable_lang~ decorator.

#+BEGIN_SRC python
  @enable_lang
  @loading
  async def send_page(consumer, client_data, lang=None):
      print(lang)
#+END_SRC

Or you could read it with the ~lang~ key of the ~client_data~ parameter.

 #+BEGIN_SRC python
    @loading
    async def send_page(consumer, client_data):
	print(client_data["data"]["lang"])
#+END_SRC

You can read the tutorial [[#/tutorials/internationalize-with-subdomains/][Internationalize with subdomains]] to see how to create a multilingual website with subdomains.

* Loading
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/loading/
:TITLE: Loading
:DESCRIPTION: Loading management of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

It is very useful when the database access is slow or you access external services like APIs. You can make a loading animation while the page is being rendered.

For example, first create a template called ~loading.html~.

#+BEGIN_SRC html
  <div
    style="
    position: fixed;
    inset: 0;
    z-index: 9999;
    backdrop-filter: blur(3px);
    "
></div>
#+END_SRC

This code will blur the entire page. You can customize it as you like.

Add a tag with ~#loading~ to your main layout, or HTML fragment that all templates share.

#+BEGIN_SRC html
    <section id="loading"></section>
#+END_SRC

  Now you can make ~tools_template.py~ in the app or root folder with the following content.

  #+BEGIN_SRC python
    from django.template.loader import render_to_string
    from liveview.context_processors import get_global_context

    async def toggle_loading(consumer, show=False):
	"""Toogle Loading template."""
	data = {
	    "action": ("Show" if show else "Hide") + " loading",
	    "selector": "#loading",
	    "html": render_to_string(
		"loading.html", get_global_context(consumer=consumer)
	    )
	    if show
	    else "",
	}
	await consumer.send_html(data)


    def loading(func):
	"""Decorator: Show loading."""

	async def wrapper(*args, **kwargs):
	    await toggle_loading(args[0], True)
	    result = await func(*args, **kwargs)
	    await toggle_loading(args[0], False)
	    return result

	return wrapper
#+END_SRC

And in the action file, you can use the ~@loading~ decorator.

#+BEGIN_SRC python
  from app.tools_template import loading

  @loading
  async def send_page(consumer, client_data, lang=None):
      my_context = await get_context(consumer=consumer)
      html = await get_html(template, my_context)
      data = {
	  "action": client_data["action"],
	  "selector": "#main",
	  "html": html,
      }
      data.update(my_context)
      await consumer.send_html(data)
#+END_SRC

This will render the loading HTML in ~#loading~ before running the action and clear all the HTML when finished.

* Lost connection
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/lost-connection/
:TITLE: Lost connection
:DESCRIPTION: Lost connection management of Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

It may be the case that the connection is lost, when user has lost the internet connection or the server has been restarted, and it's a problem because Django LiveView depends on a constant connection. In these cases, the client automatically will try to reconnect to the server. But while this happens, the user will have to be informed and any type of interaction blocked. If you do not block user interactions, actions will accumulate in the browser until communication is reestablished. Where they will all be sent at once. If, for example, the user impatiently presses the next page button 10 times, the user will skip 10 pages. It is a problem for him and for the server that will process many instructions at once.

To solve this problem, you can create a tag with the ~#no-connection~ id in your main layout, or HTML fragment that all templates share.

#+BEGIN_SRC html
  <section id="no-connection" class="no-connection no-connection--hide">
      <h2>Lost connection</h2>
      <p>Trying to reconnect...</p>
  </section>
#+END_SRC

Add add the followind styles.

#+BEGIN_SRC css
  .no-connection {
      position: fixed;
      inset: 0;
      z-index: 9999;
      background-color: black;
      color: white;
      display: flex;
      justify-content: center;
      align-items: center;
      flex-direction: column;
  }

  .no-connection--hide {
      display: flex;
  }
#+END_SRC

If there is no connection, the ~#no-connection~ will be displayed with ~.no-connection--show~ class. Otherwise, it will be hidden with the ~.no-connection--hide~ class.

* Deploy
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/deploy/
:TITLE: Deploy
:DESCRIPTION: Deploy Django LiveView to production.
:NAVIGATOR-ACTIVE: docs
:END:

You can deploy Django LiveView using any web server like reverse proxy.

** Nginx

 I recommend using Nginx. Here is an example of how to configure. Replace ~example.com~ with your domain and ~my-project~ with your folder name.

#+BEGIN_SRC nginx
server {
    listen 80;
    server_name example.com;

    location / {
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header Host $host;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Host $server_name;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_redirect off;
    }

    location /static {
        include /etc/nginx/mime.types;
        root /var/www/my-project;
    }

    location /media {
        include /etc/nginx/mime.types;
        root /var/www/my-project;
    }

    location = /favicon.ico { access_log off; log_not_found off; }
}
#+END_SRC

It is important to note that the ~proxy_set_header~ lines are necessary for the WebSocket to work. You can see more about it in [[https://channels.readthedocs.io/en/latest/deploying.html][Channels]].

* FAQ
:PROPERTIES:
:ONE: one-custom-default-doc
:CUSTOM_ID: /docs/faq/
:TITLE: FAQ (Frequently Asked Questions)
:DESCRIPTION: Frequently asked questions about Django LiveView.
:NAVIGATOR-ACTIVE: docs
:END:

** Do I need to know JavaScript to use Django LiveView?

No, you don't need. You can create SPAs without using APIs, without JavaScript, and without learning anything new. If you know Python, you know how to use Django LiveView.

** Can I use JavaScript?

Yes, you can. You can use JavaScript to capture events, send and receive strings over a WebSockets channel.

** Can I use Django's native tools?

Of course. You can still use all of Django's native tools, such as its ORM, forms, plugins, etc.

** Do I need to use React, Vue, Angular or any other frontend framework?

No. All logic, rendering and state is in the backend.

** Can I use Django REST Framework or GraphQL?

Yes, you can.

** Who finances the project?

Only me and my free time. If you want to support the project, you can be my [[https://liberapay.com/androsfenollosa/][patron]].


* Tutorials
:PROPERTIES:
:ONE: one-custom-default-tutorials
:CUSTOM_ID: /tutorials/
:TITLE: Tutorials
:DESCRIPTION: Tutorials about Django LiveView.
:NAVIGATOR-ACTIVE: tutorials
:END:

** Tutorials

Learn how to create a Django LiveView application step by step.

- [[#/tutorials/quickstart/][Quickstart]]
- [[#/tutorials/internationalize-with-subdomains/][Internationalize with subdomains]]

* Quickstart
:PROPERTIES:
:ONE: one-custom-default-page
:CUSTOM_ID: /tutorials/quickstart/
:TITLE: Quickstart
:DESCRIPTION: Get started with Django LiveView the easy way.
:NAVIGATOR-ACTIVE: tutorials
:END:

Welcome to the Quickstart guide. Here you will learn how to create your first Realtime SPA using Django LiveView. I assume you have a basic understanding of Django and Python.

All the steps are applied in a [[https://github.com/Django-LiveView/minimal-template][minimalist template]].

** 1. Install Django

Install Django, create a project and an app.

** 2. Install LiveView

Install django-liveview with ~pip~.

#+BEGIN_SRC sh
pip install django-liveview
#+END_SRC

** 3. Modify the configuration

Add ~liveview~ to your installed ~INSTALLED_APPS~.

#+BEGIN_SRC python
INSTALLED_APPS = [
    "daphne",
    "channels",
    "liveview",
]
#+END_SRC

Then indicate in which previously created App you want to implement LiveView.

#+BEGIN_SRC python
LIVEVIEW_APPS = ["website"]
#+END_SRC

** 4. Migration

Execute the migrations so that the LiveView tables are generated.

#+BEGIN_SRC python
python manage.py migrate
#+END_SRC

** 5. ASGI

Modify the ASGI file, ~asgi.py~ to add the LiveView routing. In this example it is assumed that settings.py is inside core, in your case it may be different.

#+BEGIN_SRC python
import os
import django

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "core.settings")
django.setup()

from channels.auth import AuthMiddlewareStack
from django.core.asgi import get_asgi_application
from channels.security.websocket import AllowedHostsOriginValidator
from channels.routing import ProtocolTypeRouter, URLRouter
from django.urls import re_path
from liveview.consumers import LiveViewConsumer


application = ProtocolTypeRouter(
    {
        # Django's ASGI application to handle traditional HTTP requests
        "http": get_asgi_application(),
        # WebSocket handler
        "websocket": AuthMiddlewareStack(
            AllowedHostsOriginValidator(
                URLRouter([re_path(r"^ws/liveview/$", LiveViewConsumer.as_asgi())])
            )
        ),
    }
)
#+END_SRC

** 6. Create your first Action

Place where the functions and logic of the business logic are stored. We will start by creating an action to generate a random number and print it.

Create inside your App a folder called ~actions~, here will go all the actions for each page. Now we will create inside the folder a file named ~home.py~.

#+BEGIN_SRC python
# my-app/actions/home.py
from liveview.context_processors import get_global_context
from core import settings
from liveview.utils import (
    get_html,
    update_active_nav,
    enable_lang,
    loading,
)
from channels.db import database_sync_to_async
from django.templatetags.static import static
from django.urls import reverse
from django.utils.translation import gettext as _
from random import randint

template = "pages/home.html"

# Database

# Functions

async def get_context(consumer=None):
    context = get_global_context(consumer=consumer)
    # Update context
    context.update(
        {
            "url": settings.DOMAIN_URL + reverse("home"),
            "title": _("Home") + " | Home",
            "meta": {
                "description": _("Home page of the website"),
                "image": f"{settings.DOMAIN_URL}{static('img/seo/og-image.jpg')}",
            },
            "active_nav": "home",
            "page": template,
        }
    )
    return context


@enable_lang
@loading
async def send_page(consumer, client_data, lang=None):
    # Nav
    await update_active_nav(consumer, "home")
    # Main
    my_context = await get_context(consumer=consumer)
    html = await get_html(template, my_context)
    data = {
        "action": client_data["action"],
        "selector": "#main",
        "html": html,
    }
    data.update(my_context)
    await consumer.send_html(data)

async def random_number(consumer, client_data, lang=None):
    my_context = await get_context(consumer=consumer)
    data = {
        "action": client_data["action"],
        "selector": "#output-random-number",
        "html": randint(0, 10),
    }
    data.update(my_context)
    await consumer.send_html(data)
#+END_SRC

There are several points in the above code to keep in mind.

- ~template~ is the name of the template that will be rendered.
- ~get_context()~ is a function that returns a dictionary with the context of the page.
- ~send_page()~ is the function that will be executed when the page is loaded.
- ~random_number()~ is the function that will be executed when the button is clicked.

** 7. Create the base template

Now we will create the base template, which will be the one that will be rendered when the page is loaded.

Create a folder called ~templates~, or use your template folder, inside your App and inside it create another folder called ~layouts~. Now create a file called ~base.html~.

#+BEGIN_SRC html
  {# my-app/templates/layouts/base.html #}
  {% load static i18n %}
  <!doctype html>{% get_current_language as CURRENT_LANGUAGE %}
  <html lang="{{ CURRENT_LANGUAGE }}">
      <head>
	  <meta charset="utf-8">
	  <title>{{ title }}</title>
	  <meta
	      name="viewport"
	      content="width=device-width, initial-scale=1.0, shrink-to-fit=no"
	  >
	  <meta
	      name="description"
	      content="{{ meta.description }}"
	  >
	  <meta
	      property="og:image"
	      content="{{ meta.image }}"
	  >
	  <script type="module" src="{% static 'js/main.js' %}" defer></script>
      </head>
      <body
		  data-host="{{ request.get_host }}"
		  data-debug="{{ DEBUG }}"
		  data-controller="page"
	  >
	  <main id="main" class="main-container">{% include page %}</main>
      </body>
  </html>
#+END_SRC

In the future we will define ~main.js~, a minimal JavaScript to connect the events and the WebSockets client.

** 8. Create the page template

We will create the home page template, which will be the one that will be rendered when the page is loaded.

Create a folder called ~pages~ in your template folder and inside it create a file called ~home.html~.

#+BEGIN_SRC html
  {# my-app/templates/pages/home.html #}
  {% load static %}

  <main>
      <p>
	  <button
	      data-action="click->page#run"
	      data-liveview-action="home"
	      data-liveview-function="random_number"
	  >Random number</button>
      </p>
      <h2 id="output-random-number"></h2>
  </main>
#+END_SRC

As you can see, we have defined a button to launch the action of generating the random number (~button~) and the place where we will print the result (~output-random-number~).

** 9. Create frontend

Now we are going to create the frontend, the part where we will manage the JavaScript events and invoke the actions.

Download [[https://github.com/Django-LiveView/frontend/archive/refs/heads/main.zip][frontend]] and unzip it in your static folder. You will be left with the following route: ~/static/js/~.

** 10. Create View

We will create the view that will render the page for the first time (like Server Side Rendering). The rest of the times will be rendered dynamically (like Single Page Application).

In a normal Django application we would create a view, ~views.py~, similar to the following:

#+BEGIN_SRC python
# my-app/views.py
from django.shortcuts import render

# Create your views here.
def home(request):
    return render(request, "pages/home.html")
#+END_SRC

With LiveView, on the other hand, you will have the following structure.

#+BEGIN_SRC python
# my-app/views.py
from django.shortcuts import render
from .actions.home import get_context as get_home_context

from liveview.utils import get_html

async def home(request):
    return render(request, "layouts/base.html", await get_home_context())
#+END_SRC

** 11. Create URL

Finally, we will create the URL that will render the page.

#+BEGIN_SRC python
# my-app/urls.py
from django.urls import path

from .views import home

urlpatterns = [
    path("", home, name="home"),
]
#+END_SRC

** 12. Run the server

Run the server.

#+BEGIN_SRC sh
  python3 manage.py runserver
#+END_SRC

And open the browser at ~http://localhost:8000/~. You should see the home page with a button that generates a random number when clicked.

#+ATTR_HTML: :class center-block image image--responsive
[[#/img/quickstart/minimal-template.webp][Random number]]

You can also interact with [[https://django-liveview-demo-minimal-template.andros.dev/][the online demo]].

Congratulations! You have created your first Realtime SPA using Django LiveView.

The next step is to create a more complex application. You can read other [[#/tutorials/][tutorials]] or go to the [[#/docs/install/][documentation]].

* Internationalize with subdomains
:PROPERTIES:
:ONE: one-custom-default-page
:CUSTOM_ID: /tutorials/internationalize-with-subdomains/
:TITLE: Internationalize with subdomains
:DESCRIPTION: Create a multilingual website with subdomains.
:NAVIGATOR-ACTIVE: tutorials
:END:

Here you will learn how to create a multilingual website using Django LiveView.

We using subdomains to define the language (~en.example.com~, ~es.example.com~...), instead of using prefixes in addresses (~example.com/en/blog/~, ~example.com/es/blog/~). They simplify SEO, maintain consistency in the Sitemap and are easy to test.

We will use the following structure:

- ~example.com~ and ~en.example.com~ for English.
- ~es.example.com~ for Spanish.

** 1. Configure the subdomains

In your ~settings.py~ file, add all domains that will be used.

#+BEGIN_SRC python
ALLOWED_HOSTS = ["example.com", "en.example.com", "es.example.com"]
#+END_SRC

** 2. Configure the languages

And add or modify the following settings in the same file (~settings.py~).

#+BEGIN_SRC python
  # Languages

  # Enable internationalization
  USE_I18N = True

  # Default language
  LANGUAGE_CODE = "en"

  # Available languages
  LANGUAGES = [
      ("en", _("English")),
      ("es", _("Spanish")),
  ]

  # Locale paths
  LOCALE_PATHS = (BASE_DIR / "locale/",)
#+END_SRC

** 3. Redirection with Middleware

Create a middleware that redirects the user to the correct subdomain and sets the language. If the user enters ~en.example.com~ or ~example.com~, English language will be activated. If the user enters ~es.example.com~, Spanish language will be activated. And if the user enters ~en.example.com~, it will be redirected to ~example.com~.

Create a file called ~middlewares.py~ in your project folder and add the following code.

#+BEGIN_SRC python
  from django.utils import translation
  from django.conf import settings
  from django.utils.translation import get_language
  from django.http import HttpResponseRedirect

  def language_middleware(get_response):
      # One-time configuration and initialization.

      def middleware(request):
	  # Code to be executed for each request before
	  # the view (and later middleware) are called.

	  # Set the language based on the domain
	  # Example:
	  # "example.com" and "en.example.com" -> en
	  # "es.example.com" -> es

	  # Get the domain from the request
	  domain = request.META["HTTP_HOST"]
	  # Get the subdomain
	  domain_list = domain.split(".")
	  subdomain = domain_list[0] if len(domain_list) == 3 else None
	  # Set the language
	  if get_language() != subdomain:
	      translation.activate(subdomain)

	  # Redirect default language to main domain
	  # Example: "en.example.com" -> "example.com"
	  if subdomain == settings.LANGUAGE_CODE:
	      return HttpResponseRedirect("http://example.com")

	  response = get_response(request)

	  # Code to be executed for each request/response after
	  # the view is called.

	  return response

      return middleware
#+END_SRC

Now, add the middleware to the ~MIDDLEWARE~ list in ~settings.py~.

#+BEGIN_SRC python
  MIDDLEWARE = [
      ...
      "middlewares.language_middleware",
  ]
#+END_SRC

** 4. Set multilingual texts

In any of your HTML templates, you can use translation tags to display multilingual texts.

#+BEGIN_SRC
  {% load i18n %}

  <h1>{% trans "Hello" %}</h1>

  <p>{% blocktrans %}This is a multilingual website.{% endblocktrans %}</p>

#+END_SRC

For titles and descriptions, you can use the ~meta~ dictionary in the action with ~_("text")~ to translate the texts.

#+BEGIN_SRC python
  from liveview.context_processors import get_global_context
  from django.conf import settings
  from liveview.utils import (
      get_html,
      update_active_nav,
      enable_lang,
      loading,
  )
  from django.utils.translation import gettext as _
  from django.templatetags.static import static
  from django.urls import reverse

  ...
  context.update(
      {
	  "url": settings.DOMAIN_URL + reverse("home"),
	  "title": _("Home") + " | Home",
	  "meta": {
	      "description": _("Home page of the website"),
	  },
      }
  )
  ...
#+END_SRC

For the url of the page, you can edit the ~urls.py~ file to include the language.

#+BEGIN_SRC python
  from django.urls import path
  from django.utils.translation import gettext as _
  from .views import home

  urlpatterns = [
      path(_("home") + "/", home, name="home"),
      path(_("about") + "/", about, name="about"),
  ]
#+END_SRC

** 5. Make messages

Create the ~locale~ folder in the root of your project and run the following commands.

#+BEGIN_SRC sh
  ./manage.py makemessages -l en
  ./manage.py makemessages -l es
#+END_SRC

The files ~locale/en/LC_MESSAGES/django.po~ and ~locale/es/LC_MESSAGES/django.po~ will be created. You can edit them with a text editor or use a translation tool like [[https://poedit.net/][Poedit]].

** 6. Compile messages

After translating the texts, compile the messages.

#+BEGIN_SRC sh
./manage.py compilemessages
#+END_SRC

Your multilingual website is ready. You can test it by entering ~example.com~, ~en.example.com~ and ~es.example.com~.

** 7. Selector of languages

You can create a selector of languages in the header of your website.

#+BEGIN_SRC html
  {% load i18n %}
  {% get_current_language as CURRENT_LANGUAGE %}
  {% get_available_languages as AVAILABLE_LANGUAGES %}
  <ul>
      {# Display the current language #}
      <li>
	      <a href="#" disabled>{{ CURRENT_LANGUAGE }}</a>
      </li>
      {# Display the other languages #}
      {% for language in AVAILABLE_LANGUAGES %}
      {% if language.0 != CURRENT_LANGUAGE %}
      <li>
	  <a href="http{% if request.is_secure %}s{% endif %}://{{ language.0 }}.{{ DOMAIN }}">
	      {{ language.0 }}
	  </a>
      </li>
      {% endif %}
      {% endfor %}
  </ul>
#+END_SRC

The above code will create a list of languages with the current language disabled.

Or also simple links with the subdomain.

#+BEGIN_SRC html
  <a href="http://en.example.com">
      English
  </a>

  <a href="http://es.example.com">
      Español
  </a>
  {% endfor %}
#+END_SRC

* Source code
:PROPERTIES:
:ONE: one-custom-default-page
:CUSTOM_ID: /source-code/
:TITLE: Source code
:DESCRIPTION: List of all related source code.
:NAVIGATOR-ACTIVE: source code
:END:

You can find all the source code in the following repositories:

- [[https://github.com/Django-LiveView/liveview][LiveView]]: Source code of the Django framework and app published in pip.
- [[https://github.com/Django-LiveView/docs][Website and Docs]]: All documentation, including this same page.
- Templates
    - [[https://github.com/Django-LiveView/starter-template][Starter]]: Check all the features of Django LiveView.
    - [[https://github.com/Django-LiveView/minimal-template][Minimal]]: The minimal template to get started.
    - [[https://github.com/Django-LiveView/frontend][Frontend]]: Frontend assets.
- Demos
    - [[https://github.com/Django-LiveView/demo-snake][Snake]]: The classic game of Snake.

* Books
:PROPERTIES:
:ONE: one-custom-default-page
:CUSTOM_ID: /books/
:TITLE:
:DESCRIPTION: Books about Django LiveView.
:NAVIGATOR-ACTIVE: books
:END:

There are no books about Django LiveView yet. But you can find book about Django working with HTML over the Wire technology.


** Building SPAs with Django and HTML Over the Wire: Learn to build real-time single page applications with Python (English Edition)

#+ATTR_HTML: :class center-block image image--cover-book
[[#/img/books/building-spas.avif][Building SPAs with Django and HTML Over the Wire]]

Buy:

- [[https://www.packtpub.com/product/building-spas-with-django-and-html-over-the-wire/9781803240190][Packt]]
- [[https://www.amazon.com/Real-time-Django-over-Wire-Channels-ebook/dp/B0B3DV54ZT/][Amazon.com]]
- [[https://www.amazon.es/Real-time-Django-over-Wire-Channels-ebook/dp/B0B3DV54ZT/][Amazon.es]]
