Javascript 如何在meteor.helper中等待计算,直到由于template.autorun中的依赖项更改而重新计算为止?
当反应性变量发生变化时,我总是会遇到以下错误:Javascript 如何在meteor.helper中等待计算,直到由于template.autorun中的依赖项更改而重新计算为止?,javascript,meteor,meteor-helper,meteor-tracker,Javascript,Meteor,Meteor Helper,Meteor Tracker,当反应性变量发生变化时,我总是会遇到以下错误: Exception in template helper: Error: $in needs an array at Error (native) at Object.ELEMENT_OPERATORS.$in.compileElementSelector (http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:182
Exception in template helper: Error: $in needs an array
at Error (native)
at Object.ELEMENT_OPERATORS.$in.compileElementSelector (http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1827:15)
at http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1509:19
at Function._.each._.forEach (http://localhost:3000/packages/underscore.js?46eaedbdeb6e71c82af1b16f51c7da4127d6f285:157:22)
at operatorBranchedMatcher (http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1489:5)
at compileValueSelector (http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1393:12)
at http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1372:9
at Function._.each._.forEach (http://localhost:3000/packages/underscore.js?46eaedbdeb6e71c82af1b16f51c7da4127d6f285:157:22)
at compileDocumentSelector (http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1355:5)
at _.extend._compileSelector (http://localhost:3000/packages/minimongo.js?cdf1a26cf7719fa9471a8017c3defd5aea812727:1332:12)
我怀疑罪犯是w
(被动变量)
看看这个:
Template.cList.onCreated(function(){
var self = this;
self.d = new ReactiveVar()
self.w = new ReactiveVar()
self.autorun(function() {
var b = A.findOne(Pi());
if (b && b.array) {
var h = Subs.subscribe('B', b.array)
self.d.set(h.ready()) // is subscription ready?
self.w.set(b.array)
}
});
});
Template.cList.helpers({
cLists: function () {
if (Template.instance().d.get() && Template.instance().w.get()) { // run only when d and w is ready
return B.find({_id: {$in:Template.instance().w.get()}}, {fields: {title:1, src:1}});
}
}
});
让我们一步一步地分解
Pi()
Pi()
更改,以下变量将更改:b&&b.array&&h&&self.d.set(h.ready())和&self.w.set(b.array)
cList
是在页面更改后立即计算的,而不等待自动运行重新计算完成,这就是抛出错误的原因cLists
根据依赖项更改显示正确列表。用户界面确实没有问题。但是这个警告看起来很肮脏我想避免上述警告的方法是在依赖项更改时等待cList。我该怎么做?如何在meteor.helper中等待计算,直到由于template.autorun中的依赖项更改而重新计算为止?罪魁祸首是来自
meteorhacks:subs manager的的就绪回调。。。使用模板订阅更改它将避免错误
Template.cList.onCreated(function(){
var self = this;
self.d = new ReactiveVar()
self.w = new ReactiveVar()
self.autorun(function() {
var b = A.findOne(Pi());
if (b && b.array) {
self.subscribe('B', b.array)
self.w.set(b.array)
}
});
});
Template.cList.helpers({
cLists: function () {
if (Template.instance().subscriptionsReady() && Template.instance().w.get()) { // run only when subscription and w is ready
return B.find({_id: {$in:Template.instance().w.get()}}, {fields: {title:1, src:1}});
}
}
});