When introducing Rails 5 and the dashboard, we generated the schema file
without dropping the database first. When doing so locally, migrations
aren't always executed in order, changing the order of the columns.
This table will store which reports (stats, results, ...) will be shown
for a certain process (polls, budgets, ...).
Note Rails fails to save a poll and its report when both are new records
if we add a `validate :process, presence: true` rule. Since it caused a
lot of trouble when creating records for tests during factories rule
completely. Instead, I've created the `results_enabled=` and
`stats_enabled=` methods, so tests are easier to set up, while also
automatically creating a report if it doesn't already exist. This also
decouples form structure and database implemenation.
Originally I named this table `enabled_reports` and instead of having
`stats` and `results` columns, it had an `enabled` column and a `kind`
column, which would be set to "stats" or "results". However, although
that table would allow us to add arbitrary reports easily, I found the
way we had to handle the `has_many` relationship was a bit too complex.
We need a way to manually expire the cache for a budget or poll without
expiring the cache of every budget or poll.
Using the `updated_at` column would be dangerous because most of the
times we update a budget or a poll, we don't need to regenerate their
stats.
We've considered adding a `stats_updated_at` column to each of these
tables. However, in that case we would also need to add a similar column
in the future to every process type whose stats we want to generate.
The condition `params[:page_id] != 0` didn't work properly when editing
the homepage because in that case the parameter was `nil`, and the line
`SiteCustomization::Page.find(@card.site_customization_page_id)` raised
an exception because it couldn't find a page with a `nil` ID.
Fixing the issue while maintaining the check against `0` lead to complex
code, and so allowing `nil` in the database and assuming cards with no
`site_customization_page_id` belonged in the homepage seemed to be the
easiest solution.
