Marshal GraphQL execution results to java object

Question

I searched a lot into SO, but unfortunately any of the proposed solutions fits to me.

I am going to describe the key points:

1. My REST project is built upon OpenAPI and the OpenAPI maven generator plugin.
2. By the jaxrs-spec generator I produce the application DTOs.
3. By the graphql-nodejs-express-server generator I produce the GraphQL schema files.
4. The REST web service accepts, as optional, a GraphQL query in order to filter/reduce the verbosity of the answer.

The GraphQL ExecutionResult.getData() method returns an instance of a LinkedHashMap.

The question is: How can I marshall the above LinkedHashMap to the corresponding DTO?

Thank you so much in advance!

---- Edit ----

I wish to improve and simplify my question.

I have a DTO such the following one:

public class ResponseDTO {
    private Integer id;
    private String description;
}

I filter it by GraphQL:

GraphQLSchema graphQLSchema = getGraphQLSchema();
String        graphqlQuery  = "{ ResponseDTO { id } }";

ExecutionInput builder = ExecutionInput
    .newExecutionInput()
    .query(graphqlQuery)
    .build();

ExecutionResult executionResult = GraphQL
    .newGraphQL(graphQLSchema)
    .build()
    .execute(builder);
    
LinkedHashMap graphQLData = executionResult.getData();

//TODO How can I convert 'graphQLData' to a `ResponseDTO` instance?

ResponseDTO responseDTO = ???;

Answer 1

I finally found the solution:

LinkedHashMap<String, Object> dataMap      = executionResult.getData();
String                        dataKey      = dataMap.keySet().toArray()[0].toString();
HashMap<String, Object>       dataValue    = (HashMap<String, Object>)dataMap.get(dataKey);

fixTypeId(
    dataContext.getClass(),
    dataValue
);

ObjectMapper             objectMapper = new ObjectMapper();

objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);            objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
objectMapper.registerModule(new JavaTimeModule());
objectMapper.registerModule(new JaxbAnnotationModule());
objectMapper.setDateFormat(new StdDateFormat().withColonInTimeZone(true));           objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

String dataJSON = objectMapper.writeValueAsString(dataValue);

ResponseDTO responseDTO = objectMapper.readValue(
    dataJSON,
    ResponseDTO.class
);

Where fixTypeId is:

@SuppressWarnings("unchecked")
private void fixTypeId(Class<?> refClass, Map<String, Object> dataMap) {
    JsonTypeInfo typeInfoAnnotation = refClass.getDeclaredAnnotation(JsonTypeInfo.class);
    JsonTypeName typeNameAnnotation = refClass.getDeclaredAnnotation(JsonTypeName.class);

    if ((null != typeInfoAnnotation) && (null != typeNameAnnotation)) {
        String typeInfo = typeInfoAnnotation.property();
        String typeName = typeNameAnnotation.value();

        log.trace(
            "Adding \"{} = {}\" type identifier.",
            typeInfo,
            typeName
        );

        dataMap.put(typeInfo, typeName);
    }

    dataMap
        .entrySet()
        .stream()
        .filter(entry -> (entry.getValue() instanceof Map))
        .forEach(entry -> {
            Field field = null;

            try {
                field = refClass.getDeclaredField(entry.getKey());
            } catch (NoSuchFieldException exception) {
                log.error(exception.getMessage(), exception);
                throw new RuntimeException(exception);
            }

            fixTypeId(
                field.getType(),
                (Map<String, Object>)entry.getValue()
            );
        });
}