如何 return 'then' 回调函数的结果到环回 4 控制器

Question

我正在尝试对我的 loopback4 控制器内的 TypeORM 实体执行 'find' 函数。

问题是，根据 TypeORM 文档，我在附加到 'createConnection' 函数的 'then' 回调函数中执行了查询。因此，'findOne' 调用的结果超出了控制器方法

的范围

//this is the controller method signature
async findById(@param.path.number('id') id: number): Promise<Pratica> {

    createConnection({
      type: 'oracle',
      host: '10.64.2.226',
      port: 1521,
      sid: 'NPRA02S',
      username: 'sua03e',
      password: 'iniziale',
      entities: [
        Pratica
      ],
      logging: true
    }).then(async connection => {
      let praticaRepository = connection.getRepository(Pratica);

      // I have to return this as a result parameter in the controller
      let pratica = await praticaRepository.findOne({ protocolloaci: id });

    }).catch(error => console.log(error));

  }

我也尝试过以下方法，但如果没有 async/await

，我会知道如何管理它们

//this is the controller method signature
async findById(@param.path.number('id') id: number): Promise<Pratica> {

    let connection = await createConnection({
      type: 'oracle',
      host: '10.64.2.226',
      port: 1521,
      sid: 'NPRA02S',
      username: 'sua03e',
      password: 'iniziale',
      entities: [
        Pratica
      ],
      logging: true
    })

    let praticaRepository = connection.getRepository(Pratica);

    return await praticaRepository.findOne({ protocolloaci: id }) || new Pratica;

  }

提前致谢

Answer 1

试试下面的代码

async findById(@param.path.number('id') id: number): Promise<Pratica> {

        return new Promise( (resolve)=>{

            createConnection({
              type: 'oracle',
              host: '10.64.2.226',
              port: 1521,
              sid: 'NPRA02S',
              username: 'sua03e',
              password: 'iniziale',
              entities: [
                Pratica
              ],
              logging: true
            }).then(async connection => {
              let praticaRepository = connection.getRepository(Pratica);

              // I have to return this as a result parameter in the controller
              const pratica = await praticaRepository.findOne({ protocolloaci: id });
              resolve(pratica); // return using resolve
            }).catch(error => console.log(error));
        });
}

Answer 2

更清洁的方法是使用 Promise.resolve:

async findById(@param.path.number('id') id: number): Promise<Pratica> {
  try {

     const connection = **await** createConnection({
       type: 'oracle',
       host: '10.64.2.226',
       port: 1521,
       sid: 'NPRA02S',
       username: 'sua03e',
       password: 'iniziale',
       entities: [
        Pratica
       ],
       logging: true
     });

     let praticaRepository = connection.getRepository(Pratica);

     const pratica = await praticaRepository.findOne({ 
       protocolloaci: id 
     });

     return **Promise.resolve**(
        this.response.status(200).send(pratica)
     );

  } catch(err) {
     console.log(error.message);
     return Promise.resolve(
       this.response.status(400).send({ 
         error: err.message, 
         status: 400 
       })
     );
  }
}

如何 return 'then' 回调函数的结果到环回 4 控制器

How to return the result of a 'then' callback function to the loopback 4 controller

typescript

typeorm

loopback4