How to delete cache record from Apollo GraphQL client with readQuery and writeQuery - apollo

Question

The Apollo GraphQL team says that readQuery and writeQuery are good for 95% of the use cases. I am using useMutation and update and want to remove an item from a cache without having to call refetchQueries. My code is as follows:
const [deleteSpeaker] = useMutation(DELETE_SPEAKER, {
update(cache, { data: {deleteSpeaker}}) {
const { speakers} = cache.readQuery({query: GET_SPEAKERS});
cache.writeQuery({
query: GET_SPEAKERS,
data: { speakers: speakers.filter(speaker => speaker.id !== deleteSpeaker.id) }
});
},
});
What gets returned from readQuery leads me to think I should be filtering for speakers.datalist but when I do that, the cache does not update.
What is the correct way to update cache to reflect a removed record from the GET_SPEAKERS query.
export const DELETE_SPEAKER = gql`
mutation DeleteSpeaker($speakerId: Int!) {
deleteSpeaker(speakerId: $speakerId) {
id
first
last
favorite
}
}
`;
and GET_SPEAKERS
export const GET_SPEAKERS = gql`
query {
speakers {
datalist {
id
first
last
favorite
company
}
}
}
`;

Answer 1

reading apollo docs, this should be something lke:
const [deleteSpeaker] = useMutation(DELETE_SPEAKER, {
update(cache, { data: {deleteSpeaker}}) {
cache.modify({
id: cache.identify(deleteSpeaker.id),
fields: {
comments(existingSpeakerRefs, { readField }) {
return existingSpeakerRefs.filter(
speaker => deleteSpeaker.id !== readField('id', speakerRef)
);
},
},
});
},
});