如何使用 Type-GraphQL、TypeORM 和依赖注入实现 Resolver-Inheritance

Question

我正在尝试扩展 Type-GraphQL 提供的解析器继承示例，除了用 TypeORM 存储库替换静态数据。

以下是 PersonResolver 如何扩展 ResourceResolver 以及它如何将 persons 数组作为 ResourceResolver 构造函数的第二个参数传递。

const persons: Person[] = [
  {
    id: 1,
    name: "Person 1",
    age: 23,
    role: PersonRole.Normal,
  },
  {
    id: 2,
    name: "Person 2",
    age: 48,
    role: PersonRole.Admin,
  },
];

@Resolver()
export class PersonResolver extends ResourceResolver(Person, persons) {
   ...
}

ResourceResolver 内部

export function ResourceResolver<TResource extends Resource>(
  ResourceCls: ClassType<TResource>,
  resources: TResource[],
) {
  const resourceName = ResourceCls.name.toLocaleLowerCase();

  // `isAbstract` decorator option is mandatory to prevent multiple registering in schema
  @Resolver(_of => ResourceCls, { isAbstract: true })
  @Service()
  abstract class ResourceResolverClass {
    protected resourceService: ResourceService<TResource>;

    constructor(factory: ResourceServiceFactory) {
      this.resourceService = factory.create(resources);
    }
...
}

而在 ResourceServiceFactory

@Service()
export class ResourceServiceFactory {
  create<TResource extends Resource>(resources?: TResource[]) {
    return new ResourceService(resources);
  }
}

export class ResourceService<TResource extends Resource> {
  constructor(protected resources: TResource[] = []) {}

    getOne(id: number): TResource | undefined {
    return this.resources.find(res => res.id === id);
}

我想知道实现 ResourceResolver 的最佳方法，但我想传递来自 TypeORM 的存储库而不是静态数据。

这是原始示例 - https://github.com/MichalLytek/type-graphql/tree/master/examples/resolvers-inheritance。

非常感谢任何帮助或建议。

Answer 1

我相信你必须在你的解析器函数中做一些像这样时髦的事情：

function createBaseResolver<T extends BaseEntity>(suffix: string, objectTypeCls: T) {
    @Resolver({ isAbstract: true })
    abstract class BaseResolver {  
      @Query(type => [objectTypeCls], { name: `getAll${suffix}` })
      async getA(@Arg("id", type => Int) id: number): Promise<T> {
          let beCastedObj = (<typeof BaseEntity> objectTypeCls.constructor); // https://github.com/Microsoft/TypeScript/issues/5677
          return beCastedObj.findOne({ where: { id:id } }) as Promise<T>;
      }
    }
  
    return BaseResolver;
  }

在另一个文件中...

const PersonBaseResolver = createBaseResolver("person", Person);

@Resolver(of => Person)
export class PersonResolver extends PersonBaseResolver {
  // ...
}

编辑：OP 在评论中询问他是否认为这是一个好的模式。我才刚刚开始学习这个，所以不要把我的话当作福音。然而。我在进行下一步时遇到了麻烦：定义自定义参数。如果您为 @Args() 使用自定义 classes（推荐使用 auto-validate），那么 typescript/typegraphql 在编译时需要该信息。如果这些参数不会在任何 children 中发生变化，您可以保留 parent 的解析器 as-is，但如果它们发生变化，您需要一种方法来传递自定义参数。

我通过将解析器装饰器移动到 children.

来完成此操作

示例Parent：

abstract class BaseUserCreatedEntityResolver {

    async get(args: any, ctx: any): Promise<T> {
      this.checkForLogin(ctx);
      let beCastedObj = (<typeof UserCreatedEntity>objectTypeCls.constructor);
      args = Object.assign(args, { userCreator: ctx.req.session.userId })
      let a =  beCastedObj.findOne({ where: args }) as any;
      return a;
    }

    async getAll(args: any, ctx: any): Promise<T> {
      this.checkForLogin(ctx);
      let beCastedObj = (<typeof UserCreatedEntity>objectTypeCls.constructor);
      args = Object.assign(args, { userCreator: ctx.req.session.userId });
      beCastedObj.create(args);
      return beCastedObj.find({ where: args }) as any;
    }

    async add(args:any, ctx: any): Promise<T> {
      this.checkForLogin(ctx);
      let beCastedObj = (<typeof UserCreatedEntity>objectTypeCls.constructor);
      args = Object.assign(args, { userCreator: ctx.req.session.userId });
      let entity = await beCastedObj.create(args)[0];
      await entity.save();
      return entity as any;
    }

    async delete(args:any, ctx: any): Promise<T> {
      this.checkForLogin(ctx);
      let entity = await this.get(args,ctx);
      await entity.remove();
      return new Promise(()=>true);
    }

    async update(args:any, ctx: any): Promise<T> {
      this.checkForLogin(ctx);
      let entity = await this.get(args,ctx);
      delete args['userCreator'];// this should've been filtered out in child param definition, but adding it here just in case

      Object.assign(entity,args);
      await entity.save();
      return entity;
    }

    checkForLogin(ctx:any){
      if(!ctx.req.session.userId) throw new Error("User not logged in");
    }

  }

示例Child：

@ArgsType()
class GetAllArgs {
  @Field()
  date:Date;
}

//...

@Query(() => Entity)
async getAllEntitiesName(@Args() args :GetAllArgs, @Ctx() ctx: any) {
  return super.get(args,ctx);
}

我很喜欢这种范式。如果我有一个函数在所有 children 解析器中都不会改变，我将创建该函数并在 parent 中修饰它。出于这个原因，我将 parent 作为可自定义的 function-class，而不仅仅是基本的 class。

如何使用 Type-GraphQL、TypeORM 和依赖注入实现 Resolver-Inheritance

How to implement Resolver-Inheritance with Type-GraphQL, TypeORM, and dependency injection

factory

dependency-injection

typeorm

typegraphql