Can I execute code when a query is garbage collected?

[danielbrauer]

I'm making an app which decrypts remote image data before displaying it in the browser. The decrypted result is stored using URL.createObjectURL(), but this will leak memory if not released at some point using URL.revokeObjectURL(). I would love to use React Query to handle fetching and caching this data, but it's not clear to me how I would make sure that the URLs are revoked at the appropriate time.

[danielbrauer]

Is this perhaps the sort of thing this PR is intended to enable? #867

[pianomansam]

Five years later, but this is how I just accomplished this very thing in v5:

queryClient.getQueryCache().subscribe((event) => {
  if (
    event.type === 'removed' &&
    ['CanvasCroppedImage', 'CanvasMultiTagImage'].includes(
      event.query.queryKey[0],
    ) &&
    typeof event.query.state.data === 'string' &&
    event.query.state.data.length > 0
  ) {
    URL.revokeObjectURL(event.query.state.data);
  }
});

[TkDodo]

That’s not bad 👍 . You can also use meta to “tag” queries that are url images.