This repository demonstrates an issue where GraphQL @BatchMapping methods are invoked multiple times when executed through subscriptions in a Spring Boot application.
The project uses:
- Java
- Spring Boot
- Spring GraphQL
- Maven
It defines a simple domain with Owner entities and exposes GraphQL queries, subscriptions, and batch mappings. The main focus is to showcase how, under certain conditions, the @BatchMapping method is called more than once per subscription event, which may not be the expected behavior.
Access the GraphQL endpoint (default: http://localhost:8080/graphql) using a GraphQL client.
- Use a GraphQL subscription that triggers the batch mapping.
- Observe the logs or run project tests to see that the
@BatchMappingmethod is called multiple times per subscription event.
The repo is equipped with some simple tests, most passing but with one failing, testBatchWorkingOnSubscription it will only pass if the batch mapping method is only called once, currently it is being called 10 times, because that is the number of owners being returned
The batchmapping is indeed working for queries, but it seems that when triggered by a subscription it does not batch entities
This project is for demonstration purposes.