在没有绑定的情况下利用beforeMove/afterMove? [英] utilizing beforeMove/afterMove without a binding?

问题描述

我需要检测何时在 observableArray 中移动项目.在当前版本(2.1.0)中，我通过在所有删除事件上调用setTimeout并等待看看是否紧随其后的是添加事件来完成此操作:

I need to detect when items are moved in an observableArray. In my current version (2.1.0) I accomplish this by calling setTimeout on all delete events and waiting to see if an add event follows immediately on its heels:

  var delayed = [];
  var key; /* obtained by comparing original observableArray with updated list and iterating all differences */

  if( /** record exists in original list but not new list ) {
     // it was deleted, we don't immediately fire a notification (it may get re-inserted in a moment)
     delayed[key] = setTimeout(function() { sendDeleteNotification(key); }, 0);
  }
  else if( /** record exists in new list but not original */ ) {
     if( delayed[key] ) { 
        // it was deleted and immediately re-added (it's a move)
        clearTimeout(delayed[key]); 
        sendMoveNotification( key );
     }
     else {
        // it was added
        sendAddedNotification( key );
     }
  }

在淘汰赛2.2中，我看到 beforeMove和afterMove的新事件.但是，我找不到任何以编程方式利用它们的方法.

In knockout 2.2, I see new events for beforeMove and afterMove. However, I can't find any means to utilize them programmatically.

最终目标是能够立即在数据库中镜像客户端更改，但不能显示添加/删除来代替移动事件.在列表中上移或下移的记录不应标记为已删除然后重新添加.

The end goal is to be able to mirror client changes in the database immediately, but not show an add/delete in place of a move event. A record moved up or down in the list shouldn't be marked as deleted and then newly added.

可以在JavaScript中直接使用新的beforeMove/afterMove绑定(例如事件模型)来改善这一点吗?

Can the new beforeMove/afterMove bindings be utilized in JavaScript directly (e.g. event model?) to improve this?

干杯

推荐答案

我使用的答案基于此jsfiddle .

beforeMove和afterMove函数可以通过简单的订阅来访问:

The beforeMove and afterMove functions can be accessed by a simple subscription:

var obs = ko.observableArray();
obs.subscribe(function( arrayOfValues ) {
   console.log('moving', arrayOfValues);
}, undefined, 'beforeMove');

obs.subscribe(function( arrayOfValues ) {
   console.log('moved', arrayOfValues);
}, undefined, 'afterMove');

但是，事实证明这并不是特别有用，因为它返回更改索引的数组中的所有元素.例如，如果我从列表中删除一条记录，则删除后的每条记录都会得到一个移动的事件.

However, it turns out this wasn't particularly useful as it returns all the elements in the array that change index. For instance, if I delete a record from the list, I get a moved event for every record after the deleted one.

所以我会坚持超时，直到发现更好的地方.

So I'll be sticking with the timeout until I find something better.

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