如何使用类型-graphql和RESTDataSource

Question

我想知道如何在type-graphql中使用RESTDataSource，从而在redis中正确地缓存。如果能举个小例子，我会很感激的。

目前，我使用DI容器来获取服务，该服务是从RestDataSource类扩展而来的，但这不是正确的方式。

BookmarkResolver.ts

import { Resolver, FieldResolver, Root, Query, Ctx, Authorized } from 'type-graphql';
import { DealService } from '../service/DealService';
import { AvailableLocale } from '../enum/AvailableLocale';
import { Bookmark } from '../entity/Bookmark';

@Resolver(_of => Bookmark)
export class BookmarkResolver {
  constructor(private dealService: DealService) {}

  @FieldResolver()
  async wordpressDeal(@Root() bookmark: Bookmark) {
    return await this.dealService.getDealById(bookmark.item_id, AvailableLocale.STAGING);
  }
}

DealService.ts

import { Service } from 'typedi';
import { AbstractService } from './AbstractService';
import { AvailableLocale } from '../enum/AvailableLocale';

@Service()
export class DealService extends AbstractService {
  baseURL = process.env.DEAL_SERVICE_URL;

  async getDealById(dealId: string | number, locale: AvailableLocale) {
    const response = await this.get(
      'deals/' + dealId,
      { locale }
    );

    return this.dealReducer(response);
  }

  dealReducer(deal: any) {
    return {
      id: deal.id || 0,
      title: deal.title
    };
  }
}

AbstractService.ts

import { RESTDataSource, HTTPCache } from 'apollo-datasource-rest';
import { Service } from 'typedi';

@Service()
export class AbstractService extends RESTDataSource {
  constructor() {
    super();
    this.httpCache = new HTTPCache();
  }
}

Answer 1

通过ApolloServer的上下文共享RESTDataSource。通过@Ctx()装饰器访问上下文，在解析器中使用它。

1.定义RESTDataSource

根据apollo-datasource-rest example定义数据源。

export class TodoDataSource extends RESTDataSource {
  constructor() {
    super();
    this.baseURL = "https://jsonplaceholder.typicode.com/todos";
  }

  async getTodos(): Promise<Todo[]> {
    return this.get("/");
  }
}

2.创建DataSource实例并将其放入上下文中

当您启动服务器时，通过定义一个创建数据源的函数来add data sources to the context。

const server = new ApolloServer({
  schema,
  playground: true,
  dataSources: () => ({
    todoDataSource: new TodoDataSource(),
  }),
});

3.访问解析器中的DataSource

使用@Ctx()装饰器访问解析器中的上下文，以便可以使用数据源。

@Resolver(Todo)
export class TodoResolver {
  @Query(() => [Todo])
  async todos(@Ctx() context: Context) {
    return context.dataSources.todoDataSource.getTodos();
  }
}

https://github.com/lauriharpf/type-graphql-restdatasource上完整的、可运行的示例