graphql-modules-preset requires __isTypeOf

[mzl-md]

Which packages are impacted by your issue?

@graphql-codegen/graphql-modules-preset

Describe the bug

Problem

After updating the codegen libs, our typescript typecheck fails with Property '__isTypeOf' is missing in type

Package	Change
@graphql-codegen/cli (source)	5.0.7 -> 6.0.0
@graphql-codegen/graphql-modules-preset (source)	4.0.17 -> 5.0.0
@graphql-codegen/typescript (source)	4.1.6 -> 5.0.0
@graphql-codegen/typescript-resolvers (source)	4.5.2 -> 5.0.0

Workaround

When we add __isTypeOf: undefined to the object instances, it works again.

Suspected Problem

typescript-resolvers now generates resolver types without __isTypeOf instead of optional, but graphql-modules-preset still generates the type Pick<Types.MyTypeResolvers, DefinedFields['MyType'] | '__isTypeOf'>. So the module types now require a __isTypeOf: any attribute.

Your Example Website or App

none

Steps to Reproduce the Bug or Issue

1. Generate types for any schema with a query using the given dependencies

Expected behavior

As a user I expect the generated module types to not include __isTypeOf anymore if they are not part of the generated resolver types.

Screenshots or Videos

No response

Platform

• OS: macOS
• NodeJS: v20.19.5
• graphql version: 16.11.0
• @graphql-codegen/* version(s): 5.0.0 (see description)

Codegen Config File

import type {CodegenConfig} from '@graphql-codegen/cli'

const config: CodegenConfig = {
generates: {
'./src/schema/': {
config: {
avoidOptionals: true,
inputMaybeValue: 'T | null | undefined',
makeResolverTypeCallable: true,
mappers: {},
maybeValue: 'T | null | undefined',
optionalInfoArgument: true,
optionalResolveType: true,
useIndexSignature: true
},
plugins: [
{
add: {
content: '/* eslint-disable */'
}
},
'typescript',
'typescript-resolvers'
],
preset: 'graphql-modules',
presetConfig: {
baseTypesPath: '../generated-types/graphql.ts',
filename: 'generated-module-types.ts',
useGraphQLModules: false
}
}
},
schema: 'src/schema/**/schema.graphql'
}

export default config

Additional context

No response

[mzl-md]

Hi @eddeee888, any news on this topic?

[eddeee888]

Thanks for the nudege @mzl-md !

I've released an alpha version, could you please try if it works:

@graphql-codegen/graphql-modules-preset@5.0.1-alpha-20250923133238-5b0d040aca3a2c6010e25d814892e72e6926f3b7

[mzl-md]

Seems to be working, thank you @eddeee888 !

We are encountering another problem: We use resolver types of GraphQL interfaces to define base classes with shared code. With typescript-resolvers@5.0.0 these resolver types do not contain any properties. Is this intended?

[eddeee888]

Hey @mzl-md !

That is correct, we wanted to remove it because it is not the default GraphQL resolver behaviour. Relevant message thread here.

However if you are using makeExecutableSchema from @graphql-tools, there's an option that supports this custom behaviour. I'm checking with the team to see what we should do here

[eddeee888]

This is released here: https://github.com/dotansimha/graphql-code-generator/releases/tag/release-1758713024882

Please follow the other thread for updates about the interface resolver behaviours