discourse/db/migrate/20250714010001_backfill_themeable_site_settings.rb
Martin Brennan 19af83d39e
FEATURE: Themeable site settings (#32233)
This commit introduces the concept of themeable site settings,
which is a new tool for theme authors that lives alongside theme
modifiers and theme settings. Here is a quick summary:

* Theme settings - These are custom settings used to control UI and functionality within your theme or component and provide configuration options. These cannot change core Discourse functionality.
* Theme modifiers - Allows a theme or a component to modify selected server-side functionality of core Discourse as an alternative to building a plugin.
* Themeable site settings (new) - Allows a theme (not components) to override a small subset of core site settings, which generally control parts of the UI and other minor functionality. This allows themes to have a greater control over the full site experience.

Themeable site settings will be shown for all themes, whether the theme
changes
the value or not, and have a similar UI to custom theme settings.

We are also introducing a new page at
`/admin/config/theme-site-settings` that
allows admins to see all possible themeable site settings, and which
themes
are changing the value from the default.

### Configuration

Theme authors can configure initial values themeable site settings using
a section in the `about.json` file like so:

```json
"theme_site_settings": {
  "search_experience": "search_field"
}
```

These values will not change when the theme updates, because we cannot
know if admins have manually changed them.

### Limitations

Themeable site settings are only really intended to control elements of
the UI, and when retrieving their value we require a theme ID, so these
limitations apply:

- Themeable site settings cannot be used in Sidekiq jobs
- Themeable site settings cannot be used in markdown rules
- Themeable site settings will be cached separately to client site
settings using theme ID as a key
- Themeable site settings will override keys on the `siteSettings`
service on the client using the application preloader
- `SiteSetting.client_settings_json` will not include themeable site
settings, instead you can call `SiteSetting.theme_site_settings_json`
with a theme ID

### Initial settings

There are only two site settings that will be themeable to begin with:

* `enable_welcome_banner`
* `search_experience`

And our new Horizon theme will take advantage of both. Over time, more
settings that control elements of the UI will be exposed this way.
2025-07-16 11:00:21 +10:00

35 lines
1.2 KiB
Ruby

# frozen_string_literal: true
class BackfillThemeableSiteSettings < ActiveRecord::Migration[7.2]
def up
initial_themeable_site_settings = %w[enable_welcome_banner search_experience]
initial_themeable_site_settings.each do |setting|
db_data_type, db_value =
DB.query_single("SELECT data_type, value FROM site_settings WHERE name = ?", setting)
# If there is no value in the DB, it means the admin hasn't changed it from the default,
# and theme site settings will just use the default value.
next if db_value.nil?
theme_ids = DB.query_single("SELECT id FROM themes WHERE NOT component")
theme_ids.each do |theme_id|
# ThemeSiteSetting has an identical schema to SiteSetting, so we can use the same values
# and data types.
DB.exec(
"INSERT INTO theme_site_settings (name, data_type, value, theme_id, created_at, updated_at)
VALUES (:setting, :data_type, :value, :theme_id, NOW(), NOW())
ON CONFLICT (name, theme_id) DO NOTHING",
setting:,
data_type: db_data_type,
value: db_value,
theme_id:,
)
end
end
end
def down
raise ActiveRecord::IrreversibleMigration
end
end