GraphQL 和数据加载器使用 graphql-java-kickstart 库 [英] GraphQL and Data Loader Using the graphql-java-kickstart library

问题描述

我正在尝试使用 graphql-java-kickstart 库中的 DataLoader 功能:

I am attempting to use the DataLoader feature within the graphql-java-kickstart library:

https://github.com/graphql-java-kickstart

我的应用程序是使用 2.3.0.RELEASE 的 Spring Boot 应用程序.我使用的是 graphql-spring-boot-starter 库的 7.0.1 版.

My application is a Spring Boot application using 2.3.0.RELEASE. And I using version 7.0.1 of the graphql-spring-boot-starter library.

该库非常易于使用，并且在我不使用数据加载器时也能正常工作.然而，我被 N+1 SQL 问题所困扰，因此需要使用数据加载器来帮助缓解这个问题.当我执行一个请求时，我最终得到这个:

The library is pretty easy to use and it works when I don't use the data loader. However, I am plagued by the N+1 SQL problem and as a result need to use the data loader to help alleviate this issue. When I execute a request, I end up getting this:

Can't resolve value (/findAccountById[0]/customers) : type mismatch error, expected type LIST got class com.daluga.api.account.domain.Customer

我确定我在配置中遗漏了一些东西，但我真的不知道那是什么.

I am sure I am missing something in the configuration but really don't know what that is.

这是我的 graphql 架构:

Here is my graphql schema:

type Account {
  id: ID!
  accountNumber: String!
  customers: [Customer]
}

type Customer {
  id: ID!
  fullName: String
}

我创建了一个 CustomGraphQLContextBuilder:

I have created a CustomGraphQLContextBuilder:

@Component
public class CustomGraphQLContextBuilder implements GraphQLServletContextBuilder {

    private final CustomerRepository customerRepository;

    public CustomGraphQLContextBuilder(CustomerRepository customerRepository) {
        this.customerRepository = customerRepository;
    }

    @Override
    public GraphQLContext build(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) {
        return DefaultGraphQLServletContext.createServletContext(buildDataLoaderRegistry(), null).with(httpServletRequest).with(httpServletResponse).build();
    }

    @Override
    public GraphQLContext build(Session session, HandshakeRequest handshakeRequest) {
        return DefaultGraphQLWebSocketContext.createWebSocketContext(buildDataLoaderRegistry(), null).with(session).with(handshakeRequest).build();
    }

    @Override
    public GraphQLContext build() {
        return new DefaultGraphQLContext(buildDataLoaderRegistry(), null);
    }

    private DataLoaderRegistry buildDataLoaderRegistry() {
        DataLoaderRegistry dataLoaderRegistry = new DataLoaderRegistry();

        dataLoaderRegistry.register("customerDataLoader",
                new DataLoader<Long, Customer>(accountIds ->
                        CompletableFuture.supplyAsync(() ->
                                customerRepository.findCustomersByAccountIds(accountIds), new SyncTaskExecutor())));

        return dataLoaderRegistry;
    }
}

我还创建了一个 AccountResolver:

I also have create an AccountResolver:

public CompletableFuture<List<Customer>> customers(Account account, DataFetchingEnvironment dfe) {
    final DataLoader<Long, List<Customer>> dataloader = ((GraphQLContext) dfe.getContext())
            .getDataLoaderRegistry().get()
            .getDataLoader("customerDataLoader");

     return dataloader.load(account.getId());
}

这里是客户存储库:

public List<Customer> findCustomersByAccountIds(List<Long> accountIds) {

    Instant begin = Instant.now();

    MapSqlParameterSource namedParameters = new MapSqlParameterSource();
    String inClause = getInClauseParamFromList(accountIds, namedParameters);

    String sql = StringUtils.replace(SQL_FIND_CUSTOMERS_BY_ACCOUNT_IDS,"__ACCOUNT_IDS__", inClause);

    List<Customer> customers = jdbcTemplate.query(sql, namedParameters, new CustomerRowMapper());

    Instant end = Instant.now();

    LOGGER.info("Total Time in Millis to Execute findCustomersByAccountIds: " + Duration.between(begin, end).toMillis());

    return customers;
}

我可以在 Customer Repository 中放置一个断点并查看 SQL 执行并返回一个 Customer 对象列表.您还可以看到模式需要一组客户.如果我删除上面的代码并放入解析器以一一获取客户......它可以工作......但是真的很慢.

I can put a break point in the Customer Repository and see the SQL execute and it returns a List of Customer objects. You can also see that the schema wants an array of customers. If I remove the code above and put in the resolver to get the customers one by one....it works....but is really slow.

我在配置中遗漏了什么会导致这种情况?

What am I missing in the configuration that would cause this?

Can't resolve value (/findAccountById[0]/customers) : type mismatch error, expected type LIST got class com.daluga.api.account.domain.Customer

感谢您的帮助！

丹

推荐答案

谢谢，@Bms bharadwaj！我的问题是理解数据加载器中的数据如何返回.我最终使用 MappedBatchLoader 将数据放入地图中.映射中的键是 accountId.

Thanks, @Bms bharadwaj! The issue was on my side in understanding how the data is returned in the dataloader. I ended up using a MappedBatchLoader to bring the data in a map. The key in the map being the accountId.

private DataLoader<Long, List<Customer>> getCustomerDataLoader() {
    MappedBatchLoader<Long, List<Customer>> customerMappedBatchLoader = accountIds -> CompletableFuture.supplyAsync(() -> {
        List<Customer> customers = customerRepository.findCustomersByAccountId(accountIds);
        Map<Long, List<Customer>> groupByAccountId = customers.stream().collect(Collectors.groupingBy(cust -> cust.getAccountId()));
        return groupByAaccountId;
    });
//    }, new SyncTaskExecutor());

    return DataLoader.newMappedDataLoader(customerMappedBatchLoader);
}

这似乎成功了，因为之前我发出数百条 SQL 语句，现在减少到 2 个(一个用于驱动程序 SQL...帐户，一个用于客户).

This seems to have done the trick because before I was issuing hundreds of SQL statement and now down to 2 (one for the driver SQL...accounts and one for the customers).

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