如何在 OnBeforeAction 中使用 wait()

Question

我看到以前的旧帖子中旧版本的 Iron-router 确实 wait() ：

before: function() {
      // let's make sure that the topPosts subscription is ready and the posts are loaded
      if (this.data()) {
        // we can then extract the userIds of the authors
        var userIds = this.data().map(function(p) { return p.userId });
        // and add the authors subscription to the route's waiting list as well
        this.subscribe('authors', userIds).wait(); **<--- this guy!**
      }
    }

以上来自https://www.discovermeteor.com/blog/reactive-joins-in-meteor/

如果我将 wait() 添加到我的 OnBeforeAction 订阅中，我会收到以下错误：

You called wait() after calling ready() inside the same computation tree.

You can fix this problem in two possible ways:

1) Put all of your wait() calls before any ready() calls.
2) Put your ready() call in its own computation with Deps.autorun.

我的等待是

waitOn: function() {
            return Meteor.subscribe('weeks', this.params.league);
        },

和 OnBeforeAction

onBeforeAction: function() {
            if (this.ready()) {
                // we can now get the latest (first in the list) week
                var week = SheetData.find().fetch()[0].week;
                this.subscribe('standings', this.params.league, week).wait();
                this.next();

            }
        }

如果我删除了 wait()，渲染模板会在我的订阅准备好之前启动。建议的修复似乎不适用。我错过了什么？

Answer 1

这是基于radzserg's answer 的类似问题的解决方案。他巧妙地在原来的waitOn函数中使用了回调函数，并没有onBeforeAction。在您的情况下，它将是：

waitOn: function() {
    var that = this;
    return Meteor.subscribe('weeks', this.params.league, function() {
        var week = SheetData.find().fetch()[0].week;
        that.wait(Meteor.subscribe('standings', that.params.league, week));
    });
}