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Airium

Bidirectional HTML-python translator.

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Key features:

  • simple, straight-forward
  • template-less (just the python, you may say goodbye to all the templates)
  • DOM structure is strictly represented by python indentation (with context-managers)
  • gives much cleaner HTML than regular templates
  • equipped with reverse translator: HTML to python
  • can output either pretty (default) or minified HTML code

Type checking

Airium ships a py.typed marker and public HTML typing helpers. Projects using Airium can run mypy normally after installing the package:

python -m pip install mypy airium
python -m mypy your_project

TagName describes standard HTML element names and HTMLAttributes provides common attribute-name completion while still allowing Airium's dynamic get_tag_ escape hatch for custom elements and attributes.

Standard tags with tag-specific stubs provide keyword completion in supported IDEs. For example, a.img( exposes image attributes such as src, alt, width, height, loading, and srcset. The img element is an HTML void element, so it must be called directly rather than used as with a.img():.

The element and attribute signatures are generated by tools/generate_html_stubs.py. Run it after updating the HTML vocabulary:

python tools/generate_html_stubs.py

The generated signatures include global HTML attributes and the standard element-specific attributes for every supported HTML element. aria-*, data-*, custom attributes, and custom elements remain available through Airium's dynamic keyword and get_tag_ escape hatches.

Generating HTML code in python using airium

Basic HTML page (hello world)

from airium import Airium

a = Airium()

a('<!DOCTYPE html>')
with a.html(lang="pl"):
    with a.head():
        a.meta(charset="utf-8")
        a.title(_t="Airium example")

    with a.body():
        with a.h3(id="id23409231", klass='main_header'):
            a("Hello World.")

html = str(a)  # casting to string extracts the value
# or directly to UTF-8 encoded bytes:
html_bytes = bytes(a)  # casting to bytes is a shortcut to str(a).encode('utf-8')

print(html)

Prints such a string:

<!DOCTYPE html>
<html lang="pl">
  <head>
    <meta charset="utf-8" />
    <title>Airium example</title>
  </head>
  <body>
    <h3 id="id23409231" class="main_header">
      Hello World.
    </h3>
  </body>
</html>

In order to store it as a file, just:

with open('that/file/path.html', 'wb') as f:
    f.write(bytes(html))

Simple image in a div

from airium import Airium

a = Airium()

with a.div():
    a.img(src='source.png', alt='alt text')
    a('the text')

html_str = str(a)
print(html_str)
<div>
    <img src="source.png" alt="alt text"/>
    the text
</div>

Table

from airium import Airium

a = Airium()

with a.table(id='table_372'):
    with a.tr(klass='header_row'):
        a.th(_t='no.')
        a.th(_t='Firstname')
        a.th(_t='Lastname')

    with a.tr():
        a.td(_t='1.')
        a.td(id='jbl', _t='Jill')
        a.td(_t='Smith')  # can use _t or text

    with a.tr():
        a.td(_t='2.')
        a.td(_t='Roland', id='rmd')
        a.td(_t='Mendel')

table_str = str(a)
print(table_str)

# To store it to a file:
with open('/tmp/airium_www.example.com.py') as f:
    f.write(table_str)

Now table_str contains such a string:

<table id="table_372">
  <tr class="header_row">
    <th>no.</th>
    <th>Firstname</th>
    <th>Lastname</th>
  </tr>
  <tr>
    <td>1.</td>
    <td id="jbl">Jill</td>
    <td>Smith</td>
  </tr>
  <tr>
    <td>2.</td>
    <td id="rmd">Roland</td>
    <td>Mendel</td>
  </tr>
</table>

Chaining shortcut for elements with only one child

New in version 0.2.2

Having a structure with large number of with statements:

from airium import Airium

a = Airium()

with a.article():
    with a.table():
        with a.thead():
            with a.tr():
                a.th(_t='Column 1')
                a.th(_t='Column 2')
        with a.tbody():
            with a.tr():
                with a.td():
                    a.strong(_t='Value 1')
                a.td(_t='Value 2')

table_str = str(a)
print(table_str)

You may use a shortcut that is equivalent to:

from airium import Airium

a = Airium()

with a.article().table():
    with a.thead().tr():
        a.th(_t="Column 1")
        a.th(_t="Column 2")
    with a.tbody().tr():
        a.td().strong(_t="Value 1")
        a.td(_t="Value 2")

table_str = str(a)
print(table_str)
<article>
  <table>
    <thead>
      <tr>
        <th>Column 1</th>
        <th>Column 2</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td>
          <strong>Value 1</strong>
        </td>
        <td>Value 2</td>
      </tr>
    </tbody>
  </table>
</article>

Options

Pretty or Minify

By default, airium biulds HTML code indented with spaces and with line breaks being line feed \n characters. It can be changed while creating an Airium instance. In general all avaliable arguments whit their default values are:

a = Airium(
    base_indent='  ',  # str
    current_level=0,  # int
    source_minify=False,  # bool
    source_line_break_character="\n",  # str
)

minify

That's a mode when size of the code is minimized, i.e. contains as less whitespaces as it's possible. The option can be enabled with source_minify argument, i.e.:

a = Airium(source_minify=True)

In case if you need to explicitly add a line break in the source code (not the <br/>):

a = Airium(source_minify=True)
a.h1(_t="Here's your table")
with a.table():
    with a.tr():
        a.break_source_line()
        a.th(_t="Cell 11")
        a.th(_t="Cell 12")
    with a.tr():
        a.break_source_line()
        a.th(_t="Cell 21")
        a.th(_t="Cell 22")
    a.break_source_line()
a.p(_t="Another content goes here")

Will result with such a code:

<h1>Here's your table</h1><table><tr>
<th>Cell 11</th><th>Cell 12</th></tr><tr>
<th>Cell 21</th><th>Cell 22</th></tr>
</table><p>Another content goes here</p>

Note that the break_source_line cannot be used in context manager chains.

indent style

The default indent of the generated HTML code has two spaces per each indent level. You can change it to \t or 4 spaces by setting Airium constructor argument, e.g.:

a = Airium(base_indent="\t")  # one tab symbol
a = Airium(base_indent="    ")  # 4 spaces per each indentation level
a = Airium(base_indent=" ")  # 1 space per one level
# pick one of the above statements, it can be mixed with other arguments

Note that this setting is ignored when source_minify argument is set to True (see above).

There is a special case when you set the base indent to empty string. It would disable indentation, but line breaks will be still added. In order to get rid of line breaks, check the source_minify argument.

indent level

The current_level being an integer can be set to non-negative value, wich will cause airium to start indentation with level offset given by the number.

line break character

By default, just a line feed (\n) is used for terminating lines of the generated code. You can change it to different style, e.g. \r\n or \r by setting source_line_break_character to the desired value.

a = Airium(source_line_break_character="\r\n")  # windows' style

Note that the setting has no effect when source_minify argument is set to True (see above).

Using airium with web-frameworks

Airium can be used with frameworks like Flask or Django. It can completely replace template engines, reducing code-files scater, which may bring better code organization, and some other reasons.

Here is an example of using airium with django. It implements reusable basic_body and a view called index.

# file: your_app/views.py
import contextlib
import inspect

from airium import Airium
from django.http import HttpResponse


@contextlib.contextmanager
def basic_body(a: Airium, useful_name: str = ''):
    """Works like a Django/Ninja template."""

    a('<!DOCTYPE html>')
    with a.html(lang='en'):
        with a.head():
            a.meta(charset='utf-8')
            a.meta(content='width=device-width, initial-scale=1', name='viewport')
            # do not use CSS from this URL in a production, it's just for an educational purpose
            a.link(href='https://unpkg.com/@picocss/pico@1.4.1/css/pico.css', rel='stylesheet')
            a.title(_t=f'Hello World')

        with a.body():
            with a.div():
                with a.nav(klass='container-fluid'):
                    with a.ul():
                        with a.li():
                            with a.a(klass='contrast', href='./'):
                                a.strong(_t="⌨ Foo Bar")
                    with a.ul():
                        with a.li():
                            a.a(klass='contrast', href='#', **{'data-theme-switcher': 'auto'}, _t='Auto')
                        with a.li():
                            a.a(klass='contrast', href='#', **{'data-theme-switcher': 'light'}, _t='Light')
                        with a.li():
                            a.a(klass='contrast', href='#', **{'data-theme-switcher': 'dark'}, _t='Dark')

                with a.header(klass='container'):
                    with a.hgroup():
                        a.h1(_t=f"You're on the {useful_name}")
                        a.h2(_t="It's a page made by our automatons with a power of steam engines.")

            with a.main(klass='container'):
                yield  # This is the point where main content gets inserted

            with a.footer(klass='container'):
                with a.small():
                    margin = 'margin: auto 10px;'
                    a.span(_t='© Airium HTML generator example', style=margin)

            # do not use JS from this URL in a production, it's just for an educational purpose
            a.script(src='https://picocss.com/examples/js/minimal-theme-switcher.js')


def index(request) -> HttpResponse:
    a = Airium()
    with basic_body(a, f'main page: {request.path}'):
        with a.article():
            a.h3(_t="Hello World from Django running Airium")
            with a.p().small():
                a("This bases on ")
                with a.a(href="https://picocss.com/examples/company/"):
                    a("Pico.css / Company example")

            with a.p():
                a("Instead of a HTML template, airium has been used.")
                a("The whole body is generated by a template "
                  "and the article code looks like that:")

            with a.code().pre():
                a(inspect.getsource(index))

    return HttpResponse(bytes(a))  # from django.http import HttpResponse

Route it in urls.py just like a regular view:

# file: your_app/urls.py
from django.contrib import admin
from django.urls import path

import your_app

urlpatterns = [
    path('index/', your_app.views.index),
    path('admin/', admin.site.urls),
]

The result ing web page on my machine looks like that:

Airium/Django templateless example

Reverse translation

Airium is equipped with a transpiler [HTML -> py]. It generates python code out of a given HTML string.

Using reverse translator as a binary:

Ensure you have installed [parse] extras. Then call in command line:

airium http://www.example.com

That will fetch the document and translate it to python code. The code calls airium statements that reproduce the HTML document given. It may give a clue - how to define HTML structure for a given web page using airium package.

To store the translation's result into a file:

airium http://www.example.com > /tmp/airium_example_com.py

You can also parse local HTML files:

airium /path/to/your_file.html > /tmp/airium_my_file.py

You may also try to parse your Django templates. I'm not sure if it works, but there will be probably not much to fix.

Using reverse translator as python code:

from airium import from_html_to_airium

# assume we have such a page given as a string:
html_str = """\
<!DOCTYPE html>
<html lang="pl">
  <head>
    <meta charset="utf-8" />
    <title>Airium example</title>
  </head>
  <body>
    <h3 id="id23409231" class="main_header">
      Hello World.
    </h3>
  </body>
</html>
"""

# to convert the html into python, just call:

py_str = from_html_to_airium(html_str)

# airium tests ensure that the result of the conversion is equal to the string:
assert py_str == """\
#!/usr/bin/env python
# File generated by reverse AIRIUM translator (version 0.3.0).
# Any change will be overridden on next run.
# flake8: noqa E501 (line too long)

from airium import Airium

a = Airium()

a('<!DOCTYPE html>')
with a.html(lang='pl'):
    with a.head():
        a.meta(charset='utf-8')
        a.title(_t='Airium example')
    with a.body():
        a.h3(klass='main_header', id='id23409231', _t='Hello World.')
"""

Transpiler limitations

so far in version 0.2.2:

  • result of translation does not keep exact amount of leading whitespaces within <pre> tags. They come over-indented in python code.

This is not however an issue when code is generated from python to HTML.

  • although it keeps the proper tags structure, the transpiler does not chain all the with statements, so in some cases the generated code may be much indented.

  • it's not too fast

Installation

If you need a new virtual environment, call:

virtualenv venv
source venv/bin/activate

Having it activated - you may install airium like this:

pip install airium

In order to use reverse translation - two additional packages are needed, run:

pip install airium[parse]

Then check if the transpiler works by calling:

airium --help

Enjoy!

Release files for airium 0.3.0

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

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