调用 ko.mapping.fromJS 后，我的扩展 observable 被“删除”答案

【问题标题】：My extended observable is getting "deleted" after call to ko.mapping.fromJS调用 ko.mapping.fromJS 后，我的扩展 observable 被“删除”
【发布时间】：2014-08-22 08:30:58
【问题描述】：

我有一个带有以下扩展器的可观察扩展：

ko.extenders.e2mElementName = function (target, options) {

    var result = ko.dependentObservable({
        read: target,
        write: function (newValue) {
            var current = target.peek();
            if (newValue != current) {

                newValue = newValue.replace(/[^0-9A-Za-z_]/g, "").replace(" ", "_");

                //check if name already exists
                if (!document._editor.elementNames)
                    document._editor.elementNames = [];

                if ($.inArray(newValue, document._editor.elementNames)) {
                    alert("The name '" + newValue + "' was already assigned to an element on this page");
                    target.notifySubscribers(current)
                } else {
                    document._editor.elementNames.remove(current);
                    document._editor.elementNames.push(newValue);
                    target(newValue);
                }

            }
        }
    }).extend({ notify: 'always' });

    //result(target());

    return result;
};

当我在构造时扩展 observable 一切正常，在我的对象构造中我有：

this.Name = ko.observable("").extend({ e2mElementName: true });

但是在我调用 mapping.fromJs 之后，我的 observable 被更改为字符串 ex: "My Name" ...

ko.mapping.fromJS(rawData, mapping, this);

如果我删除扩展器一切正常，我有可观察的包装字符串....

我做错了什么？

【问题讨论】：

标签： javascript knockout.js mapping

【解决方案1】：

你可以在调用 ko.mapping.fromJS 后添加扩展器

var applyMapping = function(rawData) {
  ko.mapping.fromJS(rawData, {}, this);
  this.name = this.name.extend({e2ElementName: true});
}

或者您可以为此使用映射插件选项

var mappingOptions = {
  // customize the creation of the name property
  name: {
    create: function(data) {
        return ko.observable(data.name).extend( {e2ElementName: true} );
    }
  }
};

ko.mapping.fromJS(data, mappingOptions, this));

【讨论】：