WARNING: This question is specific to react-admin framework
I'm trying to do an in app manual, that uses data from server to load content pages. To doing so I'm doing a custom page that fetches manual pages on componentDidMount. In this function I call react-admin crudGetList(resourceName, pagination, sortingById, filters), where filters is {and:[{condition},{language: currentLanguage}]} since I want to have the manual in different languages. I noticed that having pages in different languages in database and using crudGetList action with filters fetches the correct instances, however the state maintains old data. For example if I initially fetch data in English language, change language and go back to manual page, redux state will have pages for both languages instead of the current selected one.
Is this expected behaviour? Making the new request for manual pages shouldn't replace redux-state data to data coming from request? If is not expected should I open an issue?
React-admin uses a pattern called optimistic rendering. That means that if the app has fetched some entities in the past, if it needs to display these entities, it first shows the stale entities, then fetches the backend, and if the response differs, re-render the screen with up to date data.
For instance, when a user fetches a list of posts, react-admin stores these posts in a dictionary indexed by id:
{
123: { id: 123, title: "hello" },
456: { id: 456, title: "world" },
...
}
React-admin also stores the list of identifiers that the list should display:
[123, 456, ...]
Using these two properties, react-admin can now display the list. But it can also display the detail of a post without hitting the server first. So when a user clicks on an item in the list, react-admin uses the data from the first structure to display it right away, without waiting for the server response.
The purpose of optimistic rendering is performance: since the user doesn't need to wait for a round trip with the server, the interface is super snappy.
In your particular case, I understand that this can cause problems, because the store contains stale data that is not in the desired language. I suggest that you create a custom saga, which reacts to the language change action, and clears the store to avoid this kind of problem.
Check the documentation for custom sagas in the react-admin site: