[英]Knockout computed observable with access to observableArray
I'm having an issue using a computedObservable
. 我在使用
computedObservable
遇到了问题。 They seem pretty straight forward, but I think my use case might be a little odd. 他们看起来很直接,但我认为我的用例可能有点奇怪。 The issue is when
onBottom()
is called, it doesn't see the items that are in the container.slides()
array. 问题是当
onBottom()
时,它不会看到container.slides()
数组中的项。 Instead, I get "Undefined is not a function". 相反,我得到“未定义不是一个功能”。
Since onTop()
works fine, it makes me think that it's the relationship between Slide
and FeaturedContent
that is causing the issue, but I think it should work fine. 由于
onTop()
工作正常,它让我认为它是导致问题的Slide
和FeaturedContent
之间的关系,但我认为它应该工作正常。 Any help here would be greatly appreciated. 这里的任何帮助将不胜感激。
HTML HTML
<div class="section-block" data-bind="foreach: slides">
<div class="row well">
<div class='control'>
<a href='#' data-bind="click: moveUp, ifnot: onTop">
<i class="fa fa-arrow-up"></i>
</a>
<a href='#' data-bind="click: moveDown, ifnot: onBottom">
<i class="fa fa-arrow-down"></i>
</a>
<span class='pull-right'>Remove</span>
</div>
<h5 data-bind="text: headline"></h5>
<p data-bind="text: image"></p>
</div>
</div>
JS JS
var FeaturedContent = function() {
var self = this;
self.maxSlides = 14;
self.slides = ko.observableArray([
new Slide({}, "I should be last", "someimg", 0, self),
new Slide({}, "I should be first", "anotherimg", 1, self),
new Slide({}, "I should be second-", "anotherimg", 2, self),
]);
// ... snipped.
};
var Slide = function(contentItem, headline, image, order, container) {
var self = this;
// -- Data
self.contentItem = contentItem;
self.headline = headline;
self.image = image;
self.position = ko.observable(0);
self.onBottom = ko.computed(function() {
return (self.position() === container.slides().length - 1) ? true : false;
});
self.onTop = ko.computed(function() {
return (self.position() === 0) ? true : false;
});
return self;
};
During creating 在创建过程中
self.slides = ko.observableArray([
new Slide({}, "I should be last", "someimg", 0, self),
new Slide({}, "I should be first", "anotherimg", 1, self),
new Slide({}, "I should be second-", "anotherimg", 2, self),
]);
in the FeaturedContent
your code will create new Slide
and use self
to get container.slides().length
ie self
is the container
but slides()
has not created. 在
FeaturedContent
您的代码将创建new Slide
并使用self
来获取container.slides().length
即self
是container
但slides()
尚未创建。 It's a circle reference. 这是一个圆圈参考。 So
container.slides()
is undefined. 所以
container.slides()
是未定义的。
try something like this container.slides() && self.position() === container.slides().length - 1
尝试像这样的
container.slides() && self.position() === container.slides().length - 1
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