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dondonz

opened on Mar 2, 2025

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A validation idea from @bbakerman

Because type wiring is registered by string name, we allow a data fetcher registration to a field in an interface type because as the time of pre schema building, we don't know its an interface. I guess with more work we could "validate" this once we have the real schema in place and we know all the types

Investigate if we can validate that datafetchers are only wired on concrete types

Potential idea

allow RuntimeWiring building as we have it day (since we have no schema elements yet)
then at "schema generation time" we validate that the values in the graphql.schema.GraphQLCodeRegistry make sense
eg data fetchers only on fields of a concrete type
type resolvers ONLY on non concrete type
all non concrete types have a type resolver
etc...

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1. bbakerman commented on Mar 3, 2025

   

   bbakerman

   on Mar 3, 2025

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   I had a look into this - we have some protection in place when SchemaGenerator is used (aka SDL)

   We can detect that there are no type resolvers for an interface or union say..

   And we kinda dont really wire in data fetchers for interface fields - you can define them but they are ignored

   newTypeWiring("InterfaceType"). dataFetcher("foo", df)
   

   The above is allowed however the SchemaGenerator code will never ask for them and hence they never make their way to the GraphqlCodeRegistry

   This is only via SchemaGenerator (SDL) however - if you manually build a schema - then none of this applies and you can be missing type resolves etc...
2. bbakerman commented on Mar 3, 2025

   

   bbakerman

   on Mar 3, 2025

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   I did some more digging : graphql.schema.CodeRegistryVisitor also does some checks so that type resolvers are ALWAYS present. It asserts and fails the GraphqlSchema object creation. Its not a via a InvalidSchemaException with many errors per place - just one assert
3. bbakerman

   added a commit that references this issue on Mar 3, 2025

   POC - Validation in code registry

   3e96c16
4. dondonz

   added

   keep-openTells Stale Bot to keep PRs and issues openTells Stale Bot to keep PRs and issues open

   on Mar 19, 2025
5. dondonz

   added a commit that references this issue on Apr 3, 2026

   feat: validate that datafetchers are not wired on interface types

   This issue will close once commit 5125b74 is merged into the 'master' branch.

   5125b74

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