Query doesn't return empty entries from cached array (offset pagination) any more

We noticed that our implementation of an offset/limit bases pagination broke. This used to work with earlier Apollo Client 3.0 versions (beta/rc) but doesn’t work in 3.0.2.

Intended outcome: Custom type policies should be able to merge pagination results . useQuery should return the array with the empty entries so that the component can find the data it needs to display a page based on an offset and limit.

Actual outcome: The cache shows an array with empty entries. useQuery returns the array with the empty items removed.

Apollo Client 3.0.2 React 16.13.1

[vigie]

Hi @hwillson it is still a problem with latest. It would require an intentional update to reintroduce support for storing sparse arrays in Apollo cache. The current implementation uses a filter array operator that reduces a sparse array to a non-sparse array before storing.

The downside to no longer supporting sparse arrays, as previously noted, is that it forces clients to pad their arrays with potentially millions of nulls before storing (imagine the case where only the first and thousandth page of data had been fetched, for example).

[transcranial]

The provided offsetLimitPagination policy no longer works properly as it creates sparse arrays that are now automatically filtered: [0, 1, 2, <3 empty items>, 6] becomes [0, 1, 2, 6].