Question

我正在尝试json-rules-engine我虽然制作了一个非常简单的快速api来尝试它，但事实证明它给了我一个艰难的时间。

我试图在正文中返回的数组总是空的，即使我在地图中执行console.log实际记录消息

我有这个控制器：

'use strict';

var rulesEngine = require('./rulesEngine');

exports.run = function(req, res) {
  var outcome = rulesEngine.run(req.params.numberOfFaults);   
  res.json({outcome: outcome});
}

ruleEngine run方法就是这个

exports.run = function(numberOfFaults) {
  var facts = {
    personalFoulCount: numberOfFaults,
    gameDuration: 40
  },
  outcome = [];
  rulesEngine
    .run(facts)
    .then(events => { // run() returns events with truthy conditions 
      events.map(event => outcome.push(event.params.message))
  })
  return outcome;
};

谢谢！

Answer 1

在返回结果变量之前，您需要等待承诺完成。现在你正在调用rulesEngine并在之后返回结果，这在Javascript之类的异步语言中会立即运行。

放置＆＃39;返回结果＆＃39;在.then内部像这样：

exports.run = function(numberOfFaults) {
  var facts = {
    personalFoulCount: numberOfFaults,
    gameDuration: 40
  },
  outcome = [];
  return rulesEngine
    .run(facts)
    .then(events => { // run() returns events with truthy conditions 
      events.map(event => outcome.push(event.params.message))

      return outcome;
  })
};

Answer 2

您正在处理rulesEngine.run() synchronous，但它是asynchronous。

您必须等待它完成才能退出run功能。

例如：

      exports.run = function (req, res) {
          rulesEngine.run(req.params.numberOfFaults)
            .then((ret) => {
              res.json({
                outcome: ret,
              });
            })
            .catch((err) => {
              // Deal with error
            });
        }

     exports.run = function (numberOfFaults) {
      return new Promise((resolve, reject) => {
        const facts = {
          personalFoulCount: numberOfFaults,
          gameDuration: 40
        };

        rulesEngine
          .run(facts)
          .then(events => resolve(events.map(event => event.params.message)))
          .catch(reject);
      });
    }

如何从快速节点api返回一个数组

2 个答案: