具有剔除发布/订阅的可观察数组 [英] Observable arrays with knockout publishing/subscribing

问题描述

我正在关注该帖子:

http://www.knockmeout.net/2012/05/using-ko-native-pubsub.html

允许我的一个虚拟机与另一个虚拟机通信.我的一个viewModels有一个数组，我需要将该数组公开给另一个viewModel.如果该数组不是可观察到的，则上述文章中的方法就可以正常工作.

to allow one of my vms to communicate with the other. One of my viewModels has an array that I need to expose to another viewModel. If this array is not an observable, the method from the above post works just fine.

如果该数组是可观察的数组，则永远不会填充publishedSelectedFolders.我试图找出原因；希望这是我正在做的愚蠢的事情.

If the array is an observable array, publishedSelectedFolders is never populated. I'm trying to figure out why; hopefully it's something silly I'm doing.

这是我的jsFiddle:

Here's my jsFiddle:

http://jsfiddle.net/PTSkR/40/

如果在虚拟机中取消注释该行，则该行将按预期工作(在勾选了勾号的情况下，将填充publishedSelectedFolders).为什么会这样?

If you uncomment the line in the vm, it works as expected (publishedSelectedFolders is populated as checks are ticked). Why is this happening?

代码:

    /*
 * Pub/Sub (decouples VMs but lets them access each others' data)
 */
var postbox = new ko.subscribable();

ko.subscribable.fn.publishOn = function (topic) {
    this.subscribe(function (newValue) {
        postbox.notifySubscribers(newValue, topic);
    });

    return this; //support chaining
};

ko.subscribable.fn.subscribeTo = function (topic) {
    postbox.subscribe(this, null, topic);
    return this; //support chaining
};

/* Selection code */
this.publishedSelectedFolders = ko.observableArray().subscribeTo("SELECTED_FOLDERS");

var vm = {
    folders: ko.observableArray([{
        "folderId": "1"
    }, {
        "folderId": "2"
    }]),
    // folders: [{"folderId": "1"}, {"folderId": "2"}, {"folderId": "3"}],
    selectedFolderIds: ko.observableArray(),
};

vm.folderIndex = {};
ko.utils.arrayForEach(vm.folders, function (folder) {
    vm.folderIndex[folder.folderId] = folder;
});

/* monitors selections and publishes to the shell */
this.selectedFolders = ko.computed(function () {
    return ko.utils.arrayMap(vm.selectedFolderIds(), function (id) {
        return vm.folderIndex[id];
    });
}).publishOn("SELECTED_FOLDERS");

ko.applyBindings(vm);

推荐答案

ko.utils.array...助手不要自动解包可观察对象(请参见

The ko.utils.array... helpers do not unwrap observables automatically (see source on github). So you need to pass them the already unwrapped arrays and not the observableArray directly.

因此错误发生在您的arrayForEach呼叫中，正确的用法是:

So the error is in your arrayForEach call, where the correct usage is:

ko.utils.arrayForEach(viewModel.documents(), function(doc) {
   viewModel.documentIndex[doc.documentId] = doc; 
});

请注意viewModel.documents()末尾的()，以及如何正确使用ko.utils.arrayMap中的viewModel.selectedDocumentIds().

note the () at the end of the viewModel.documents(), and how you have used correctly the viewModel.selectedDocumentIds() in the ko.utils.arrayMap.

您固定的 JSFiddle .

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