SailsJS + Waterline 带有承诺的并发数据库请求

Question

我对 SailsJS 的水线中的并发性有点困惑。 目前我正在做这样的数据检索；

var results = {};

// Get user by id 5
User.find('5', function(err, user) {
  results.user = user;

  // when it resolves, get messages
  Message.find({userId: '5'}, function(err, messages) {
    results.messages = messages;

    // when message query resolves, get other stuff
    OtherStuff.find({userId: '5'}, function(err, otherStuff) {
      results.otherStuff = otherStuff;

      res.view({results});      
    });
  });
});

问题是数据库调用不是并发的。每个请求都在前一个的承诺得到履行后启动。我想同时启动所有请求，然后以某种方式查看是否所有承诺都已实现，如果是，则继续将结果传递给视图。

如何通过数据库请求实现这种并发？

谢谢！

Answer 1

使用async.auto。 async 模块在 Sails 中是全球化的：

async.auto({

    user: function(cb) {
        // Note--use findOne here, not find!  "find" doesn't accept
        // an ID argument, only an object.
        User.findOne('5').exec(cb);
    },
    messages: function(cb) {
        Message.find({userId: '5'}).exec(cb);
    },
    otherStuff: function(cb) {
        OtherStuff.find({userId: '5'}).exec(cb);
    }

},

    // This will be called when all queries are complete, or immediately
    // if any of them returns an error
    function allDone (err, results) {

        // If any of the queries returns an error,
        // it'll populate the "err" var
        if (err) {return res.serverError(err);}

        // Otherwise "results" will be an object whose keys are
        // "user", "messages" and "otherStuff", and whose values
        // are the results of those queries
        res.view(results);

    }
);