`cache-only` fetchPolicy results in network request after deleting cached data

[mogzol]

Issue Description

When using the cache-only fetch policy with useQuery, if data is cleared from the cache in a client.refetchQueries operation, the query will make a network request, even though that should never happen with a cache-only fetch policy.

Link to Reproduction

https://codesandbox.io/p/sandbox/apollo-cache-policy-issue-dj2w8s

Reproduction Steps

• Open the reproduction sandbox link above
• Observe that initially only the NetworkQuery request is sent, the cache-only query does correctly use only the cache
• Click the "refetch" button
• Observe that a CacheOnlyQuery network request is made.

@apollo/client version

3.11.4

[alessbell]

Hi @mogzol 👋

Thanks for opening this issue. We agree this is surprising behavior, and we're looking at changing this in Apollo Client 4.0, currently in the planning stage, to eliminate the possibility of a query with a fetch policy of cache-only of ever going to the network.

In the meantime, you can leverage onQueryUpdated which is described in the "refetching selectively" section of our docs to prevent the network request:

async function refetch() {
  await client.refetchQueries({
+    onQueryUpdated(observableQuery) {
+      return observableQuery.options.fetchPolicy !== "cache-only";
+    },
    updateCache(cache) {
      cache.modify({
        id: "ROOT_QUERY",
        fields: { user: (_, { DELETE }) => DELETE },
      });
    },
  });
}