<p>When django upgrades to a new version things break across the entire django package, including things which we don't conciously use but are internal dependencies within django. These were 'the way to do it' when troggle was first written for django 0.7 in 2006. So upgrading troggle to a new django version requires not just a broad beadth of knowledge across troggle, but also across the entire breadth of django itself. And the error messages are sometimes very unhelpful.
<p>Django release 2.2.20 is major-version 2, minor-version 2, and patch-release 20. 2.2 is the "feature release" and patch releases within each feature release are not meant to break anything. They are just to fix bugs.
<p>Things <em>will break</em> between <ahref="https://docs.djangoproject.com/en/dev/internals/release-process/">feature releases</a> which come out every 8 months. We plan on upgrading troggle on the server whenever we upgrade the server operating system, which we do only every 2-3 years between <ahref="https://wiki.debian.org/LTS">Debian LTS releases</a>.
<p>You will come to rely extensively on <ahref="https://docs.djangoproject.com/en/3.2/releases/">the release notes and versions documentation</a> which is maintained by django.
<p>You will also need to read the django <ahref="https://docs.djangoproject.com/en/3.2/howto/upgrade-version/">guide to upgrading to newer versions</a>.
<p>Documentation for the plugins is highly variable and plugin projects, being run by volunteers, can just die unexpectedly. For the django-registration plugin there are two sources of current information:<br/>
<p>but only one of these (PyPi) gives release history data - which is what you need if you get behind with the django upgrades.
<p>Django plugin documentation cannot be relied upon to tell you which version of django they require. They will complain when you run them if your version of django is too old though. Some experimentation is required.
<p>[ However django-extensions looks like it could be useful explicitly to help us through the upgrade process:
<ahref="https://pypi.org/project/django-extensions/">pypi.org/project/django-extensions/</a> (only available for django 2.2 and later). ]
<p>Upgrading the version of django used by troggle is a serious programming job. It is not just a matter of editing a few config files. You will need a full troggle software development environment set up on your machine including, most definitely, the capability of running the troggle test suite. See <ahref="troglaptop.html">how to set up a troggle software development laptop</a>. Note particularly that you will find sqlite database browser software very helpful and that you will need to know git.
<li>Use <ahref="https://docs.python.org/3/library/venv.html">pip venv</a> or virtualenv to set up a virtual python environment within which you can easily and quickly change the specific releases of python, django, django's dependencies and django plugins.
<li>Use the <em>highest release number</em> when upgrading between minor-versions of django. <br/>So we went from 1.8.19 to 1.9.13 to 1.10.8 to 1.11.29 to 2.0.13 to 2.1.15 then 2.2.19 (.20 was not released then) and next we will go to 3.2.x .
<li>Read all the release notes for <em>all</em> the intermediate releases. So from 1.1.29 we read <ahref="https://docs.djangoproject.com/en/3.0/releases/">14 sets of notes</a>: for <ahref="https://docs.djangoproject.com/en/3.0/releases/2.0/">2.0</a>, 2.0.1, 2.0.2... up to 2.0.13 .
<li>Seriously learn how to use the traceback webpage produced by django when a page crashes. There is a full record of every variable value hidden in there.
<li>You will be doing a lot of local testing just on your development machine. The default is to use the webserver built into Django: <var>python manage.py runserver 0.0.0.0:8000 -v 3</var>. Alternatively you can install and use gunicorn:
<var><ahref="https://docs.gunicorn.org/en/stable/design.html">gunicorn</a> --reload -w 9 -b :8000 wsgi</var>. the '-w' flag is for the number of worker threads and should be 2n+1 where n is the number of cpu cores on your machine.
<p>The individual releases within a minor version don't break anything but do fix bugs. So if you are on 1.10.x there is no point in getting 1.11.1 to work and you should go straight to 1.11.29 .
<p><var>check --deploy</var> gives django warnings about security issues in your settings as well as django deprecation warnings.<br>
<var>-Wall</var> is a standard python option and gives warnings of deprecated python features used by django and all the current plugins. So it tells us that django 1.11.29 is using a deprecated python language feature which will be removed from the language in python 3.9 . Python version compatibilities are documented at the top of each x.0 release note. From Django 3.0 it requires python 3.6.
<p>Even if you have made no changes to the data model, and thus the database scheme is unchanged, you still have to run the Django migration software between different Django Feature Releases, e.g. between 3.1.x and 3.2.y .
<p>Even if you have not made any changes, Django itself may have made substantial changes to its admin data model and so the database structure needs to be migrated to the new structure - even though it is an empty database since we recreate it all every time we do a data import.
<ul>
<li><ahref="https://docs.djangoproject.com/en/3.2/topics/migrations/">Django migrations documentation</a>. Read it all even if you don't understand it all yet. You will come back to it.
<li><ahref="https://realpython.com/django-migrations-a-primer/">Django Migrations: A Primer</a>. A training course in migrations. Really useful.
<li><ahref="https://docs.djangoproject.com/en/3.2/ref/django-admin/#django-admin-makemigrations">command line documentation</a> for the 'makemigrations' and 'migrate' commands.
<p>Now might also be a good idea to get familiar with using a database browser (see <ahref="troglaptop.html#dbtools">configuring a troggle laptop</a>) and use it with the example project described in the Primer article: which you should run through on your own machine.
<h4>Running troggle before and after a Django migration</h4>
<li>ensure that you have the exact version of python installed on your machine as is live for troggle on the server, e.g. do <var>$ sudo apt install python3.7.5</var>.
<li>create a venv using the version of python to be used.
<li>run the full data import <var>troggle$ python databaseReset.py reset R000</var>. It should take about 5 minutes to import everything (11 minutes on a slow core 2 duo laptop).
<li>start the runserver in the other terminal window and open a web browser to http://localhost:8000 and check important pages which we don't have tests for (yet). These are listed in <ahref="troglaptop.html">the troggle laptop installation instuctions</a>.
<li>Use the error dump tracebacks to find and correct the python code. [Running the server in a debugger would help: please add those instructions for that to this page.]
<p>On the expo server we run MariaDB as the database which has its own dependencies. In particular
<pre><code>mysqlclient==1.3.10
</code></pre>which is technically incompatible with Django 2.2 which requires 1.3.13. This incompatibility is a policy choice by the Django team. Wookey ran the Django system tests with this (April 2020) and it works fine.
Follow the instructions in the "Unit tests" section installed locally at docs/internals/contributing/writing-code/unit-tests.txt, published online at <ahref="https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/unit-tests/#running-the-unit-tests">docs.djangoproject.com/en/dev/internals/contributing/writing-code/unit-tests/</a>
This involves running <var>git clone</var> on the django source repo to download the tests. We hope we never have to do this again but in case we get incomprehensible bugs in future, we should be prepared to do so.
