Using Apollo cache as global store - for remote and local data, is very convenient.
However, while I've never used redux, I think that the most important thing about it is implementing flux: an event driven architecture in the front-end that separate logic and ensure separation of concerns.
I don't know how to implement that with Apollo. The doc says
When mutation modifies multiple entities, or if it creates or deletes entities, the Apollo Client cache is not automatically updated to reflect the result of the mutation. To resolve this, your call to useMutation can include an update function.
Adding an update
function in one part of the application that handle all cache updates; by updating queries and/or fragments for the all application, is exactly what we want to avoid in Flux / Event driven architecture.
To illustrate this, let me give a single simple example. Here, we have (at least 3 linked components)
1. InboxCount
Component that show the number of Inbox items in SideNav
query getInboxCount {
inbox {
id
count
}
}
2. Inbox list items
Component that displays items in Inbox page
query getInbox {
inbox {
id
items {
...ItemPreview
...ItemDetail
}
}
}
Both of those components read data from those GQL queries from auto generated hooks ie. const { data, loading } = useGetInboxItemsQuery()
3. AddItem
Component that creates a new item. Because it creates a new entity I need to manually update cache
. So I am forced to write
(pseudo-code)
const [addItem, { loading }] = useCreateItemMutation({
update(cache, { data }) {
const cachedData = cache.readQuery<GetInboxItemsQuery>({
query: GetInboxItemsDocument,
})
if (cachedData?.inbox) {
// 1. Update items list GetInboxItemsQuery
const newItems = cachedData.inbox.items.concat(data.items)
cache.writeQuery({
query: GetInboxItemsDocument,
data: {
inbox: {
id: 'me',
__typename: 'Inbox',
items: newItems,
},
},
})
// 2. Update another query wrapped into another reusable method, here
setInboxCount(cache, newItems.length)
}
},
})
Here, my AddItem
component must be aware of my different other queries / fragments declared in my application 😭Moreover, as it's quite verbose, complexity is increasing very fast in update
method. Especially when multiple list / queries should be updated like here
Does anyone have recommendations about implementing a more independent components? Am I wrong with how I created my queries?