以下情况如何正确使用async-await？

Question

我正在与异步等待块作斗争。我查看了网上的多种资源，但我就是不明白我在这里做错了什么：

app.post('/api/my-api', async (req, res, next) => {
try {
    filecontent = req.files.userFile.data.toString('utf8')
    console.log("decoded file : ", filecontent);
    let encoded_file = new Buffer(filecontent).toString('base64');
    var apiClass = new RPC("http://localhost:1006", "my-api");

    //the asynchronous function :
    const answ = await apiMethod.call("api", [{"file" : encoded_file, "fileName":req.files.userFile.name}], res.json);

    //the code I'd like to execute only after the previous function has finished :
    console.log("answer : ", answ);
    console.log("answering...");
    res.json(answ);
} catch (err) {
    console.log(err);
}

显然我的 console.log 在 await 行完成之前执行。我可以看出，因为异步函数中也有一个 console.log()，而我的 res.json 在收到 answ.

之前发送

如何确保异步函数在其余代码之前完成？

编辑：这里是 apiMethod.call 函数：

call(id, params) {
    let options = {
        url: this.url,
        method: "post",
        headers:
        { 
         "content-type": "text/plain"
        },
        body: JSON.stringify( {"jsonrpc": "2.0", "id": id, "method": this.procedure, "params": params })
    };
    console.log(options);
    request(options, (error, response, body) => {
        if (error) {
            console.error('An error has occurred: ', error);
        } else {
            console.log('Post successful: response: ', body);
        }
    });
}

Answer 1

问题出在 call 函数中。因为它有异步代码（request 调用），它应该被包装在 promise 中，它应该从 request.

的回调函数解析

将调用函数更新为如下内容应该有所帮助：

function call(id, params) {
  return new Promise((resolve, reject) => {
    let options = {
      url: this.url,
      method: "post",
      headers: {
        "content-type": "text/plain",
      },
      body: JSON.stringify({
        jsonrpc: "2.0",
        id: id,
        method: this.procedure,
        params: params,
      }),
    };
    console.log(options);
    request(options, (error, response, body) => {
      if (error) {
        console.error("An error has occurred: ", error);
        reject(error);
      } else {
        console.log("Post successful: response: ", body);
        resolve(body);
      }
    });
  })
}

以下情况如何正确使用async-await？

How do I use async-await properly in the following situation?

javascript

asynchronous

async-await

request-promise