CODEWITHSUNDEEP
javascriptknockout.jscomputed-observable
Johnny Cash
Johnny Cash

Reputation: 21

Knoockout computed observable write doesnt update

The following is a computed observable, and i an calling its write function, but the write doesnt update the value for the computed.

self.pagesToBeDisplayed = ko.computed({
    read: function () {
       return self.pages();
    }, write: function (totalCount) {
        self.pages(totalCount) 
    },
    deferEvaluation: true
});

I am calling the above observable as self.pagesToBeDisplayed(5). However, only the value for self.pages is updated and self.pagesToBeDisplayed is still the older value.

Upvotes: 0

Views: 54

Answers (1)

Ray
Ray

Reputation: 3959

It's working as expected:

var viewmodel = function(){
  var self = this;
  self.pages = ko.observable(2);
  self.pagesToBeDisplayed = ko.computed({
    read: function () {
       return self.pages();
    }, write: function (totalCount) {
        self.pages(totalCount) 
    },
    deferEvaluation: true
  });
  
  self.update = function(){
    self.pagesToBeDisplayed(5);
  };
};

ko.applyBindings(new viewmodel());
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>

Update via input:
<input type="number" data-bind="value: pagesToBeDisplayed">
<br>

Update via JS:
<button data-bind="click: update">Update</button>

<br><br>
Latest values:
<br>
self.pages:<span data-bind="text: pages"></span>
<br>
self.pagesToBeDisplayed:<span data-bind="text: pagesToBeDisplayed"></span>

It's probably some other part of your code that is causing the problem.

Upvotes: 0

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