This commit introduces a new feature that allows theme developers to manage the transformation of theme settings over time. Similar to Rails migrations, the theme settings migration system enables developers to write and execute migrations for theme settings, ensuring a smooth transition when changes are required in the format or structure of setting values.
Example use cases for the theme settings migration system:
1. Renaming a theme setting.
2. Changing the data type of a theme setting (e.g., transforming a string setting containing comma-separated values into a proper list setting).
3. Altering the format of data stored in a theme setting.
All of these use cases and more are now possible while preserving theme setting values for sites that have already modified their theme settings.
Usage:
1. Create a top-level directory called `migrations` in your theme/component, and then within the `migrations` directory create another directory called `settings`.
2. Inside the `migrations/settings` directory, create a JavaScript file using the format `XXXX-some-name.js`, where `XXXX` is a unique 4-digit number, and `some-name` is a descriptor of your choice that describes the migration.
3. Within the JavaScript file, define and export (as the default) a function called `migrate`. This function will receive a `Map` object and must also return a `Map` object (it's acceptable to return the same `Map` object that the function received).
4. The `Map` object received by the `migrate` function will include settings that have been overridden or changed by site administrators. Settings that have never been changed from the default will not be included.
5. The keys and values contained in the `Map` object that the `migrate` function returns will replace all the currently changed settings of the theme.
6. Migrations are executed in numerical order based on the XXXX segment in the migration filenames. For instance, `0001-some-migration.js` will be executed before `0002-another-migration.js`.
Here's a complete example migration script that renames a setting from `setting_with_old_name` to `setting_with_new_name`:
```js
// File name: 0001-rename-setting.js
export default function migrate(settings) {
if (settings.has("setting_with_old_name")) {
settings.set("setting_with_new_name", settings.get("setting_with_old_name"));
}
return settings;
}
```
Internal topic: t/109980
When a theme setting of type `upload` has a default upload, it should return the URL of the specified default upload until a custom upload is used for the setting. However, currently this isn't the case and we get null instead of the default upload URL.
The reason for this is because the `super` method of `#value` already returns the default upload URL (if there's one), so we can't pass that to `cdn_url` which expects an upload ID:
c961dcc757/lib/theme_settings_manager.rb (L212)
This commit fixes the bug by skipping the call to `cdn_url` when we fallback to the default upload for the setting value.
Similar to site settings, adds support for `refresh` option to theme settings.
```yaml
super_feature_enabled:
type: bool
default: false
refresh: true
```
Previously theme setting descriptions were defined in the `settings.yml` file like this:
```
setting_name:
default: "My Default Value"
description:
en: "English description"
fr: "French description"
```
This commit allows developers to store the localised descriptions in the theme locale files instead:
```
en:
theme_metadata:
description: Theme Description
settings:
setting_name: "The localised description for setting_name"
```
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
