淘汰赛视图模型映射停止订阅触发

Posted 2023-03-27

【中文标题】淘汰赛视图模型映射停止订阅触发

【英文标题】：Knockout viewmodel mapping stops subscription firing

【发布时间】：2018-07-21 09:30:42

【问题描述】：

我有以下主视图模型

var masterVM = (function() 
  this.PatientViewModel = ko.mapping.fromJS(new PatientViewModel());
  this.MedicalBenefit = new MedicalBenefitViewModel(this.PatientViewModel);
)();

以及以下视图模型

var PatientViewModel = function() 
  var self = this;

  self.FirstName = ko.observable();
  self.LastName = ko.observable();
  self.NationalHealthFundId = ko.mapping.fromJS(null);

  self.NationalHealthFundId.subscribe(function(newValue) 
    alert("subscribe from patient");
  );
;

var MedicalBenefitViewModel = function (patient) 
    var self = this;

    self.patient = patient;
;

在自定义绑定中的某处（绑定到患者）：

...

var observable = valueAccessor();

ko.mapping.fromJS(patient, , observable);

...

其中患者是代表患者的简单纯 json 对象。

自定义绑定执行后，订阅（alert("subscribe from patient");）停止工作，为什么？

【参考方案1】：

您已设置self.NationalHealthFundId = ko.mapping.fromJS(null);。你只能订阅一个 observable。例如，这有效：

var PatientViewModel = function() 
  var self = this;

  self.FirstName = ko.observable();
  self.LastName = ko.observable();
  self.NationalHealthFundId = ko.observable();

  self.NationalHealthFundId.subscribe(function(newValue) 
    alert("subscribe from patient");
  );
;

var vm = new PatientViewModel()
ko.applyBindings(vm);

vm.NationalHealthFundId(1);
vm.NationalHealthFundId(2);

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>