Question

所以我有这个：

function appViewModelRecord() {
                var self = this;
                self.returnedDataRecord = ko.observableArray([]);
                self.table_name = ko.observable();
                self.counta = ko.observable();
                self.countb = ko.observable();
                self.diff = ko.observable();
                //
                self.update = function() {
                    $.getJSON("@Url.HttpRouteUrl("ActionApi",new {controller="check",action="recordcount"})", function (data) {
                    $('#heartRecords').fadeTo(400, 1);
                    var mappedData = $.map(data, function (item) {
                        item.diff = item.counta - item.countb;
                        return new recordData(item);
                    });
                    self.returnedDataRecord(mappedData);
                    $('.badge').html(moment().format('DD/MM/YYYY HH:mm:ss'));
                    $('#heartRecords').fadeTo(400, 0);
                    });
                });
                };
            }

我正在使用它：

    var viewModelRecord = new appViewModelRecord();
    updateData();
    window.setInterval(updateData, 30000);
    ko.applyBindings(viewModelRecord,document.getElementById('tableRecords'));
    //
    function updateData() {
        viewModelRecord.update();
    }

我希望在每次更新时检查returnedDataRecord arrat是否有0条记录，以便有可视指示。

我应该怎么做？

更新

视图模型：

    function appViewModelRecord() {
        var self = this;
        self.returnedDataRecord = ko.observableArray([]);
        self.table_name = ko.observable();
        self.counta = ko.observable();
        self.countb = ko.observable();
        self.diff = ko.observable();
        //
        self.update = function() {
            $.getJSON("@Url.HttpRouteUrl("ActionApi",new {controller="check",action="recordcount"})", function (data) {
                $('#heartRecords').fadeTo(400, 1);
                var mappedData = $.map(data, function (item) {
                    item.diff = item.counta - item.countb;
                    return new recordData(item);
                });
                self.returnedDataRecord(mappedData);
                $('.badge').html(moment().format('DD/MM/YYYY HH:mm:ss'));
                $('#heartRecords').fadeTo(400, 0);
            });
        };
        self.howMany = ko.computed(function () {
            return self.returnedDataRecord().length;
        });
    }

和更新功能：

function updateData() {
                viewModelRecord.update();
                if (viewModelRecord.howMany() == 0) {
                    $('#noRecords').fadeTo(400, 1);
                } else {
                    $('#noRecords').fadeTo(400, 0);
                }
            }

我有“记录”数。唯一的问题是它第一次有值= 0。

UPDATE2：

按照上面的代码，这是我的主要脚本：

    var viewModel = new appViewModel();
    var viewModelRecord = new appViewModelRecord();
    ko.applyBindings(viewModel,document.getElementById('tablePallets'));
    ko.applyBindings(viewModelRecord, document.getElementById('tableRecords'));
    window.setInterval(updateData, 30000);
    updateData();

就是这样，我第一次得不到计数

Answer 1

<span data-bind="text: count"></span>
<button data-bind="click: addItem">Add Item</button>

function MyViewModel() {
 var self = this;
 self.items = ko.observableArray();

 self.count = ko.computed(function() {
     return self.items().length;
 });

 self.addItem = function(){
     self.items.push("item");
 }        
}

ko.applyBindings(new MyViewModel());

Jsfiddle

Answer 2

self.howMany = ko.computed(function () {
                return self.returnedDataRecord().length;
            });

每次更新后获得knockout observablearray长度

2 个答案: