I’m currently working on a Spring Boot project that uses GraphQL, and I need to implement a file upload functionality. I’ve set up my GraphQL schema and resolvers, but I’m unsure how to properly handle file uploads through GraphQL. Most of the examples I’ve found involve REST APIs rather than GraphQL.

So far my app looks like this:

    <dependencies>
        <!--Spring Boot-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-graphql</artifactId>
        </dependency>

        <!--GraphQL-->
        <dependency>
            <groupId>com.graphql-java</groupId>
            <artifactId>graphql-java-extended-scalars</artifactId>
            <version>${com.graphql-java}</version>
        </dependency>
        <dependency>
            <groupId>com.graphql-java-kickstart</groupId>
            <artifactId>graphql-java-servlet</artifactId>
            <version>15.2.0</version>
        </dependency>


        <!--Tests-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webflux</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.graphql</groupId>
            <artifactId>spring-graphql-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

@Configuration
public class GraphQLConfig {

    @Bean
    public RuntimeWiringConfigurer runtimeWiringConfigurer() {
        return wiringBuilder -> wiringBuilder.scalar(ApolloScalars.Upload);
    }

}

//File schema.graphqls

scalar Upload

type Mutation {
    uploadFile(file: Upload!): String
}

@Controller
public class MediaController {

    @MutationMapping
    public String uploadFile(@Argument MultipartFile file, DataFetchingEnvironment environment) {
        return "Uploaded";
    }

}