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Discover some demo projects

More about demo data

The pm prep command “prepares” the database of a given Lino site. It flushes the database and loads the demo fixtures (see also Introduction to demo fixtures). Or in other words: It deletes all data in the given database and replaces it with “factory default” demo data.

Of course you don’t want this to happen accidentally on a production server. That’s why Lino asks:

INFO Started manage.py prep (using settings)
We are going to flush your database (.../default.db).
Are you sure (y/n) ?

Demo projects included with Lino

One of the repositories installed with a Lino developer environment is the Lino Book project, a somewhat special repository:

  • It is not an application

  • It is not released on PyPI

  • It contains the main test suite for Lino.

  • It contains the Sphinx source code used to generate the very pages you are reading right now (the “Developer Guide”).

  • It contains a series of demo projects.

Let’s have a look at one of these demo projects.

The polly project

Let’s play a bit with the polly demo project:

$ go polly
$ pm prep

Now start a development server:

$ runserver

Open your browser and discover the web interface.

  • Please try to create a poll with some questions, then to enter a response to that poll.

When you got tired of playing in the web interface, let’s discover another interface: the command-line.

Playing with the Django shell

Open another terminal and start a Python shell on polly:

$ go polly
$ pm shell

Now you are almost in a normal Python shell session, with the difference that your settings.py has been loaded. Both the shell and the runserver commands are part of Django.

Try out whether the following Python commands work also on your computer.

>>> from django.conf import settings

The settings module comes from your settings.py file.

But don’t forget that we are now in the shell, no longer in your text editor. The Python process is running and Django has imported your settings.py file because it was given (in your manage.py, which was started by pm) by the DJANGO_SETTINGS_MODULE environment variable.

>>> import os
>>> os.environ['DJANGO_SETTINGS_MODULE']
'lino_book.projects.polly.settings.demo'

One well-known Django setting is INSTALLED_APPS.

>>> from pprint import pprint
>>> pprint(settings.INSTALLED_APPS)
('lino',
 'lino.modlib.about',
 'lino.modlib.jinja',
 'lino_react.react',
 'lino.modlib.printing',
 'lino.modlib.system',
 'django.contrib.contenttypes',
 'lino.modlib.gfks',
 'lino.modlib.users',
 'lino_xl.lib.xl',
 'lino_xl.lib.polls',
 'django.contrib.staticfiles',
 'django.contrib.sessions')

A Django project becomes a Lino site when its Django settings module has a variable named SITE holding an instance of a subclass of the lino.core.site.Site class.

>>> settings.SITE  
<lino_book.projects.polly.settings.demo.Site object at ...>

The attributes you gave in your settings.py file are here:

>>> settings.SITE.default_ui
'lino_react.react'

The SITE object contains much more information than what you wrote in your your settings.py file. For example, settings.SITE.installed_plugins is a tuple of the installed plugins:

>>> pprint(settings.SITE.installed_plugins)
(<lino.core.plugin.Plugin lino>,
 <lino.modlib.about.Plugin lino.modlib.about>,
 <lino.modlib.jinja.Plugin lino.modlib.jinja(needed by lino_react.react)>,
 <lino_react.react.Plugin lino_react.react(needs ['lino.modlib.jinja'])>,
 <lino.modlib.printing.Plugin lino.modlib.printing(needed by lino.modlib.system)>,
 <lino.modlib.system.Plugin lino.modlib.system(needed by lino.modlib.gfks, needs ['lino.modlib.printing'])>,
 <lino.core.plugin.Plugin django.contrib.contenttypes(needed by lino.modlib.gfks)>,
 <lino.modlib.gfks.Plugin lino.modlib.gfks(needs ['lino.modlib.system', 'django.contrib.contenttypes'])>,
 <lino.modlib.users.Plugin lino.modlib.users(needs ['lino.modlib.system'])>,
 <lino.core.plugin.Plugin lino_xl.lib.xl(needed by lino_xl.lib.polls)>,
 <lino_xl.lib.polls.Plugin lino_xl.lib.polls(needs ['lino_xl.lib.xl'])>,
 <lino.core.plugin.Plugin django.contrib.staticfiles>,
 <lino.core.plugin.Plugin django.contrib.sessions>)

These things have been put there during site startup. If you are interested in the details, read When Lino starts up.

But let’s have some more fun!

>>> from lino.api.doctest import *

The lino.api.doctest module contains a collection of utility functions that are mainly used in tested documents. But they can also help you to discover a Lino site.

>>> show_menu("robin")
- Polls : My Polls, My Responses
- Configure :
  - System : Users, Site Parameters
  - Polls : Choice Sets
- Explorer :
  - System : content types, Authorities, User types, User roles
  - Polls : Polls, Questions, Choices, Responses, Answer Choices, Answer Remarks
- Site : About, User sessions

The lino.api.doctest.show_menu() function takes a username as first mandatory argument and then prints the application menu.

Discover more demo projects

Please play also with the following demo projects in the same way as you played with polly:

  • chatter

  • noi1r

  • roger

Where “playing” means for example:

  • Try changing the site attribute languages (you need to run pm prep after doing so)

  • Change the default_ui site attribute to verify that they work with both the ExtJS (lino.modlib.extjs, the default value) and the React front end (lino_react.react). This change does not require pm prep.

Discover some plugins

Lino comes with a library of plugins. Plugins are modules you can reuse in applications. Let’s discover a few of them now.

Please read the following pages of the Lino User Guide:

Demo projects and plugins

The following table shows which demo project uses which plugin:

Plugin

noi1r

chatter

polly

roger

users

contacts

cal

comments

courses

accounting

Don’t read on

The following code snippet was used to build the projects and plugins table above, and it is used to test whether the information is correct.

>>> from importlib import import_module
>>> import rstgen
>>> rows = []
>>> projects = ["noi1r", "chatter", "polly", "roger"]
>>> plugins = ("users", "contacts", "cal", "comments", "courses", "accounting")
>>> for pname in plugins:
...     cells = [ pname ]
...     for prjname in projects:
...         settings_module = "lino_book.projects.{}.settings".format(prjname)
...         m = import_module(settings_module)
...         if not hasattr(m, "SITE"):
...             m = import_module(settings_module + ".demo")
...         cells.append("☑" if m.SITE.is_installed(pname) else "□")
...     rows.append(cells)
>>> header = ["Plugin"] + projects
>>> print(rstgen.table(header, rows))
============ ======= ========= ======= =======
 Plugin       noi1r   chatter   polly   roger
------------ ------- --------- ------- -------
 users        ☑       ☑         ☑       ☑
 contacts     ☑       □         □       ☑
 cal          ☑       □         □       ☑
 comments     ☑       ☑         □       □
 courses      □       □         □       ☑
 accounting   ☑       □         □       ☑
============ ======= ========= ======= =======