Disabling partial responses but schema awareness

[hendrikniemann]

Hello urql community!

Partial results are causing a lot of issues in our application. nulls have semantic meanings, fields are null even though they should never be null, etc. At the same time, we would like to use schema awareness for deterministic fragment matching. Is it possible to use schema awareness but turn partial results off (always treat partial results as cache misses)?

Unfortunately, the docs and API don't seem to mention a possibility to disable it.

I would apreciate any hints that could point me into the right direction.

[hendrikniemann]

While digging through the source code, I found an undocumented option: possibleTypes. It can be used to enable deterministic fragment matching without passing a schema, thus disabling all other features of schema awareness. This is exactly what I was looking for.

It is possible to test out the option with this function:

/**
 * Generates a PossibleTypesConfig from a GraphQL introspection schema.
 *
 * This function extracts abstract type (UNION and INTERFACE) to concrete type
 * mappings from the introspection schema, allowing Graphcache to match
 * fragments deterministically without heuristic fragment matching.
 *
 * @param introspectionSchema - The introspection schema containing __schema.types
 * @returns A mapping of abstract type names to arrays of concrete type names
 */
function generatePossibleTypes(introspectionSchema: typeof schema): PossibleTypesConfig {
  const possibleTypes: PossibleTypesConfig = {};

  for (const type of introspectionSchema.__schema.types) {
    if ((type.kind === "UNION" || type.kind === "INTERFACE") && type.possibleTypes != null) {
      possibleTypes[type.name] = type.possibleTypes.map((t) => t.name);
    }
  }

  return possibleTypes;
}

const exchange = cacheExchange({
  possibleTypes: generatePossibleTypes(schema),
});

This still includes the schema in the bundle but it allowed me to try out the option without a big change or having to write a utility that generate possible types.