Loopback 4: Failed @repository dependency injection (TypeError: Cannot read property 'findOne' of undefined)

Question

我正在我的 Loopback 4 应用程序上设置 Bearer Token 身份验证，我正在遵循以下一般实施：https://github.com/strongloop/loopback-next/tree/master/packages/authentication。

在我的 src/providers/auth-strategy.provider.ts 中，我需要一个存储库对象的引用才能查询我的数据源。我希望在我工作的 class 的构造函数中使用 @repository 装饰器通过依赖注入来实现这一点。

但是，当我在 @repository 装饰器创建的存储库引用上调用 findOne() 时，会产生以下错误：

TypeError: Cannot read property 'findOne' of undefined

这是我的 auth-strategy.provider.ts 版本：

import {Provider, inject, ValueOrPromise} from '@loopback/context';
import {Strategy} from 'passport';
import {
  AuthenticationBindings,
  AuthenticationMetadata,
} from '@loopback/authentication';
import {IVerifyOptions} from 'passport-http-bearer';
import {ApiClient} from '../models';
import {ApiClientRepository} from '../repositories';
import {Strategy as BearerStrategy} from 'passport-http-bearer';
import {repository} from '@loopback/repository';

export class BearerStrategyProvider implements Provider<Strategy | undefined> {
  constructor(
    @inject(AuthenticationBindings.METADATA)
    private metadata: AuthenticationMetadata,
    @repository(ApiClientRepository)
    private apiClientRepository: ApiClientRepository,
  ) {}

  value(): ValueOrPromise<Strategy | undefined> {
    // The function was not decorated, so we shouldn't attempt authentication
    if (!this.metadata) {
      return undefined;
    }

    const name = this.metadata.strategy;
    if (name === 'BearerStrategy') {
      return new BearerStrategy(this.verify);
    } else {
      return Promise.reject(`The strategy ${name} is not available.`);
    }
  }

  async verify(
    token: string,
    done: (error: any, user?: any, options?: IVerifyOptions | string) => void,
  ) {
    // call cb(null, false) when user not found
    // call cb(null, user) when user is authenticated
    let apiClient: ApiClient | null;
    try {
      apiClient = await this.apiClientRepository.findOne({
        where: {Token: token},
      });
      if (apiClient) {
        console.log("Found CLIENT!!! Here: " + apiClient.Email);
        done(null, {user: apiClient});
      } else {
        // if token not found in DB:
        done('Authentication Error.', false);
      }
    } catch (e) {
      console.log(e);
    }
  }
}

Answer 1

其实我觉得你的情况和这个问题是一样的： https://github.com/strongloop/loopback-next/issues/1835

您应该将验证函数的上下文绑定到您的 class，否则 this 不是 BearerStrategyProvider，而是 BearerStrategy，那么 this.apiClientRepository 就不是存在于 class。你可以这样绑定它：

return new BearerStrategy(this.verify.bind(this));

Loopback 4: Failed @repository dependency injection (TypeError: Cannot read property 'findOne' of undefined)

Loopback 4: Failed @repository dependency injection (TypeError: Cannot read property 'findOne' of undefined)

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