Question about using graphcache without explicit mutation updates handlers

[smhutch]

Today I worked on adding a fairly trivial new mutation to my app (createPost).
This mutation returns a Post type, as well as a nested array of items (an array of Post).

I found that when accessing this mutation result, it resolved to null for the entire createPost return type.
What's interesting, is that my schema doesn't support this value being null, but graphcache was resolving it as such.

After doing some digging, I found that:

• The network is returning the expected data.
• The result I get back from urql has incorrect data.
• If I add an empty updates handler, the data resolves correctly. Without this, the data resolves to null.
• If I omit items from the mutation, everthing works correctly. With the items, the data resolves to null.

The following line of code patches this at my end

cacheExchange({
  //....
  updates: {
     [MUTATION_FIELD_NAME]: {
        createPost: (_result, _args, _cache, _info) => {}
     }
  },
})

Am I overlooking something in the docs?

My expectation is that this would be handled automatically in the background. Do I need to add a handler to updates even if it does nothing?

[kitten]

What could be happening is that Graphcache gets into a "dead lock" situation. Fields on items that the mutation selection set needs are potentially missing so the resolution may get into an irresolvable state.

You should be able to attach the debug logging to get more info about this:

urql/exchanges/graphcache/src/types.ts

Line 548 in 00d36ce

logger?: Logger;