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[sunil: Add caption for another file too] Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org> Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>
108 lines
3.7 KiB
ReStructuredText
108 lines
3.7 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-SA-4.0
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Part 2: Skeleton
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----------------
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Let us get started with creating our FreedomBox app.
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Creating the project structure
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Create a directory structure as follows with empty files. We will fill them up
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in a step-by-step manner::
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─┬ <plinth_root>/
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├─┬ plinth/
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│ └─┬ modules/
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│ └─┬ transmission/
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│ ├─ __init__.py
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│ ├─ forms.py
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│ ├─ manifest.py
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│ ├─ urls.py
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│ ├─ views.py
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│ ├─┬ data/
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│ │ └─┬ etc/
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│ │ ├─┬ plinth/
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│ │ │ └─┬ modules-enabled/
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│ │ │ └─ transmission
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│ │ └─┬ apache2/
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│ │ └─┬ conf-available/
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│ │ └─ transmission-freedombox.conf
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│ └─┬ tests
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│ └─ __init__.py
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└─┬ actions/
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└─ transmission
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The file ``__init__.py`` indicates that the directory in which it is present is
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a Python module. For now, it is an empty file.
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FreedomBox's setup script ``setup.py`` will automatically install the
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``plinth/modules/transmission`` directory (along with other files described
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later) to an appropriate location. If you are creating an app that stays
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independent and outside of FreedomBox source tree, then ``setup.py`` script in
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your source tree will need to install it to a proper location on the system. The
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``plinth/modules/`` directory is a Python3 `namespace package
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<https://www.python.org/dev/peps/pep-0420/>`_. So, you can install it with the
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``plinth/modules/`` directory structure into any Python path and still be
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discovered as ``plinth.modules.*``.
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Tell FreedomBox that our app exists
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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The first thing to do is tell FreedomBox that our app exists. This is done by
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writing a small file with the Python import path to our app and placing it in
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``plinth/modules/transmission/data/etc/plinth/modules-enabled/``. Let us create
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this file ``transmission``:
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.. code-block:: text
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:caption: ``plinth/modules/transmission/data/etc/plinth/modules-enabled/transmission``
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plinth.modules.transmission
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This file is automatically installed to ``/etc/plinth/modules-enabled/`` by
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FreedomBox's installation script ``setup.py``. If we are writing a module that
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resides independently outside the FreedomBox's source code, the setup script
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will need to copy it to the target location. Further, it is not necessary for
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the app to be part of the ``plinth.modules`` namespace. It can, for example, be
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``freedombox_transmission``.
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Creating the App class
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^^^^^^^^^^^^^^^^^^^^^^
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In the FreedomBox framework, each app must be a class derived from the
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:class:`plinth.app.App`. Let us do that in ``__init__.py``. We will fill up the
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class later.
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.. code-block:: python3
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:caption: ``__init__.py``
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from plinth import app as app_module
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class TransmissionApp(app_module.App):
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"""FreedomBox app for Transmission."""
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app_id = 'transmission'
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def __init__(self):
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"""Create components for the app."""
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super().__init__()
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As soon as FreedomBox Service (Plinth) starts, it will load all the enabled
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modules. After this, it gives a chance to each of the modules to initialize
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itself by calling the ``init()`` method if there is such a method available as
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``<module>.init()``. The app class must be instantiated here.
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.. code-block:: python3
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:caption: ``__init__.py``
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app = None
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def init():
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"""Initialize the Transmission module."""
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global app
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app = TransmissionApp()
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setup_helper = globals()['setup_helper']
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if setup_helper.get_state() != 'needs-setup' and app.is_enabled():
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app.set_enabled(True)
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