@BatchMapping not working for mutation response

[palhoye]

Spring Boot 3.3.0 with Spring GraphQL v1.3.0

I have a GraphQL query and mutation that returns the same response.
The response is complex with nested GraphQL types and @BatchMapping at several layers.

When I execute a mutation that will return a large number of rows in the response, it breaks.
Upon investigation I see that fields marked in the controller as @BatchMapping, are not batching but running individually for each item.

When I execute a query with the exact same fragment as response and same data it works fine and I see that the fields marked as @BatchMapping works as expected by batching the data.

[rstoyanchev]

I see no reason why a mutation should work differently. Is it possible to provide a basic sample?

[palhoye]

I see no reason why a mutation should work differently. Is it possible to provide a basic sample?

Agree, it is surprising.

I'm not able to share a code example right now, but here is a shortened and obfuscated version of the GraphQL which demonstrates the issue:

Note:

1. We have a mutation and a query with the same response.
2. When the mutation is executed, the response dataloader is not invoked as expected and each item under elementItems is run as a separate batch with one element in each batch.
3. When the query is executed, the response dataloader is invoked as expected and all elementItems are run with a single dataloader in one batch.

mutation MutationExample($id: ID!, $stage: Stage!) {
    updateExample(input: {idToUpdate: $id, stage: stage}) {
        ...myFields
    }
}

query QueryExample($id: ID!) {
    ...myFields
}

fragment myFields on TypeElement {
    id
    stage
    myFieldSelection {
        numberOfDistinctElements
        elementItems {
            id
            item {
                id
                name
                owner {
                    ...userProfile
                }
            }
        }
    }
}

fragment userProfile on User {
    id
    email
    displayName
    photoUrl
    isActive
}

[rstoyanchev]

Thanks for the extra context, but I'm afraid it doesn't help enough. An issue of this kind is likely something less than obvious and could also be something in GraphQL Java. The best way to move forward is to provide a small sample (e.g. via https://start.spring.io) that demonstrates the issue.

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[MateusDadalto]

Hi, I also stumbled upon this bug in my project. Created a basic example here @rstoyanchev if you want to check

https://github.com/MateusDadalto/spring-batch-mapping-error