如何实现此功能 - nodejs

Question

我有一个需要返回承诺的ajax调用.功能如下

client.tickets.create(ticket,  function(err, req, result) {
  if (err) {    
    logger.error(err);

    return false;
  }

  return JSON.stringify(result);
});

在执行下一个操作之前,我必须等待此函数执行.我怎样才能宣传这个功能？

我尝试了以下内容,它给了我一个错误说Cannot call method then of undefined:

return client.tickets.create(ticket).then(function(result){
    return JSON.stringify(result);
},function(err){
    logger.error(err);
    return false;
});

Answer 1

你有错误,因为create()不是承诺.宣传异步功能非常简单(nodejs现在有内置的Promise支持):

function createTicket(ticket) {
    // 1 - Create a new Promise
    return new Promise(function (resolve, reject) {
        // 2 - Copy-paste your code inside this function
        client.tickets.create(ticket, function (err, req, result) {
            // 3 - in your async function's callback
            // replace return by reject (for the errors) and resolve (for the results)
            if (err) {
                reject(err);
            } else {
                resolve(JSON.stringify(result));
            }
        });
    });
}

// 4 - consume your promise with then() (resolved promise) and catch (rejected promise)
createTicket(ticket).then(function (result) {
    // deal with result here
}).catch(function (err) {
    // deal with error here
});

Answer 2

而不是手动将异步代码包装到promises中,我建议使用像Bluebird你这样做的库:

var Bluebird = require('bluebird');

//either 
client.tickets = Bluebird.promisifyAll(client.tickets);
//or 
client.tickets.createAsync = Bluebird.promisify(client.tickets.create);
...
    return client.tickets.createAsync(ticket)
      .then(JSON.stringify)
      .catch(err => {
        logger.error(error); 
        return false
      });