1.1.1 摘要
在博文《Ember.js实现单页面应用程序》中，我们介绍了使用Ember JS实现一个单页应用程序 (SPA)，这使我想起了几年前写过一个任务管理程序，通过选择日期，然后编辑时间来增加任务信息。
当时，我们是使用ASP.NET和jQuery实现了任务管理程序的，通过ajax调用ASP.NET的Webservice方法来访问数据库。
今天，我们将通过任务管理程序的实现，来介绍使用ASP.NET Web API和Knockout JS的结合使用，想必许多人都有使用过任务管理程序，其中我觉得Google日历是一个不错的任务管理器
图1 Google日历
目录
1.1.2 正文
通过图1Google日历，我们发现它使用一个Date Picker，让用户选择编辑的日期、还有一个24小时的表格，当用户点击表上的一个时间区域就显示一个弹出式窗口，让用户编辑任务的内容，现在大概了解了基本的界面设计了，接下来我们将通过ASP.NET Web API作为服务端，开放API让Knockout JS调用接口获取数据。
创建ASP.NET MVC 项目
首先，我们在VS2012中创建一个ASP.NET MVC 4 Web项目。
然后，我们打开Package Manager Console，添加Package引用，要使用的库如下：
- PM> install-package jQuery
- PM> install-package KnockoutJS
- PM> install-package Microsoft.AspNet.Web.Optimization
- PM> update-package Micrsoft.AspNet.WebApi
- PM> install-package EntityFramework
图2 ASP.NET MVC 4 Web Application
创建数据表
接着，我们在数据库中添加表TaskDays和TaskDetails，TaskDays保存所有任务的日期，那么一个日期只有一行记录保存该表中，它包含了Id（自增）和Day字段，TaskDetails保存不同时间短任务信息，它包含Id（自增)、Title、Details、Starts、Ends和ParentTaskId等字段，其中ParentTaskId保存任务的日期的Id值。
图3 表TaskDays和TaskDetails
数据传输对象
前面，我们已经定义了数据表TaskDays和TaskDetails并且通过ParentTaskId建立了表之间的关系，接下来，我们将根表定义数据传输对象，具体定义如下：
/// <summary> /// Defines a DTO TaskCalendar. /// </summary> public class TaskDay { public TaskDay() { Tasks = new List<TaskDetail>(); } public int Id { get; set; } public DateTime Day { get; set; } public List<TaskDetail> Tasks { get; set; } } /// <summary> /// Defines a DTO TaskDetail. /// </summary> public class TaskDetail { public int Id { get; set; } public string Title { get; set; } public string Details { get; set; } public DateTime Starts { get; set; } public DateTime Ends { get; set; } [ForeignKey("ParentTaskId")] [ScriptIgnore] public TaskDay ParentTask { get; set; } public int ParentTaskId { get; set; } }
上面，我们定义了数据传输对象TaskDays和TaskDetails，在TaskDays类中，我们定义了一个List<TaskDetail>类型的字段并且在构造函数中实例化该字段，通过保持TaskDetail类型的强对象引用，从而建立起TaskDays和TaskDetails之间的聚合关系，也就是TaskDay和TaskDetails是一对多的关系。
创建控制器
这里我们的ASP.NET MVC程序作为服务端向客户端开放API接口，所以我们创建控制器CalendarController并且提供数据库操作方法，具体实现如下：
/// <summary> /// The server api controller. /// </summary> public class CalendarController : ApiController { /// <summary> /// Gets the task details. /// </summary> /// <param name="id">The identifier.</param> /// <returns>A list of task detail.</returns> /// /api/Calendar/GetTaskDetails?id [HttpGet] public List<TaskDetail> GetTaskDetails(DateTime id) { } /// <summary> /// Saves the task. /// </summary> /// <param name="taskDetail">The task detail.</param> /// <returns></returns> /// /api/Calendar/SaveTask?taskDetail [HttpPost] public bool SaveTask(TaskDetail taskDetail) { } /// <summary> /// Deletes the task. /// </summary> /// <param name="id">The identifier.</param> /// <returns></returns> /// /api/Calendar/DeleteTask?id [HttpDelete] public bool DeleteTask(int id) { } }
在控制器CalendarController中我们定义了三个方法分别是SaveTask()、DeleteTask()和GetTaskDetails()，想必大家一看都知道这三个方法的作用，没错就是传统的增删查API，但我们这里并没有给出具体数据库操作代码，因为我们将使用Entity Framework替代传统ADO.NET操作。
Entity Framework数据库操作
接下来，我们定义类TaskDayRepository和TaskDetailRepository，它们使用Entity Framework对数据库进行操作，具体定义如下：
/// <summary> /// Task day repository /// </summary> public class TaskDayRepository : ITaskDayRepository { readonly TaskCalendarContext _context = new TaskCalendarContext(); /// <summary> /// Gets all tasks. /// </summary> public IQueryable<TaskDay> All { get { return _context.TaskDays.Include("Tasks"); } } /// <summary> /// Alls the including tasks. /// </summary> /// <param name="includeProperties">The include properties.</param> /// <returns></returns> public IQueryable<TaskDay> AllIncluding(params Expression<Func<TaskDay, object>>[] includeProperties) { IQueryable<TaskDay> query = _context.TaskDays; foreach (var includeProperty in includeProperties) { query = query.Include(includeProperty); } return query; } /// <summary> /// Finds the specified identifier. /// </summary> /// <param name="id">The identifier.</param> /// <returns></returns> public TaskDay Find(int id) { return _context.TaskDays.Find(id); } /// <summary> /// Inserts the or update. /// </summary> /// <param name="taskday">The taskday.</param> public void InsertOrUpdate(TaskDay taskday) { if (taskday.Id == default(int)) { _context.TaskDays.Add(taskday); } else { _context.Entry(taskday).State = EntityState.Modified; } } /// <summary> /// Saves this instance. /// </summary> public void Save() { _context.SaveChanges(); } /// <summary> /// Deletes the specified identifier. /// </summary> /// <param name="id">The identifier.</param> public void Delete(int id) { var taskDay = _context.TaskDays.Find(id); _context.TaskDays.Remove(taskDay); } public void Dispose() { _context.Dispose(); } } public interface ITaskDayRepository : IDisposable { IQueryable<TaskDay> All { get; } IQueryable<TaskDay> AllIncluding(params Expression<Func<TaskDay, object>>[] includeProperties); TaskDay Find(int id); void InsertOrUpdate(TaskDay taskday); void Delete(int id); void Save(); }
上面，我们定义类TaskDayRepository，它包含具体的数据库操作方法：Save()、Delete()和Find()，TaskDetailRepository的实现和TaskDayRepository基本相似，所以我们很快就可以使用TaskDetailRepository，具体定义如下：
/// <summary> /// Task detail repository /// </summary> public class TaskDetailRepository : ITaskDetailRepository { readonly TaskCalendarContext _context = new TaskCalendarContext(); /// <summary> /// Gets all. /// </summary> public IQueryable<TaskDetail> All { get { return _context.TaskDetails; } } /// <summary> /// Alls the including task details. /// </summary> /// <param name="includeProperties">The include properties.</param> /// <returns></returns> public IQueryable<TaskDetail> AllIncluding(params Expression<Func<TaskDetail, object>>[] includeProperties) { IQueryable<TaskDetail> query = _context.TaskDetails; foreach (var includeProperty in includeProperties) { query = query.Include(includeProperty); } return query; } /// <summary> /// Finds the specified identifier. /// </summary> /// <param name="id">The identifier.</param> /// <returns></returns> public TaskDetail Find(int id) { return _context.TaskDetails.Find(id); } /// <summary> /// Saves this instance. /// </summary> public void Save() { _context.SaveChanges(); } /// <summary> /// Inserts the or update. /// </summary> /// <param name="taskdetail">The taskdetail.</param> public void InsertOrUpdate(TaskDetail taskdetail) { if (default(int) == taskdetail.Id) { _context.TaskDetails.Add(taskdetail); } else { _context.Entry(taskdetail).State = EntityState.Modified; } } /// <summary> /// Deletes the specified identifier. /// </summary> /// <param name="id">The identifier.</param> public void Delete(int id) { var taskDetail = _context.TaskDetails.Find(id); _context.TaskDetails.Remove(taskDetail); } public void Dispose() { _context.Dispose(); } } public interface ITaskDetailRepository : IDisposable { IQueryable<TaskDetail> All { get; } IQueryable<TaskDetail> AllIncluding(params Expression<Func<TaskDetail, object>>[] includeProperties); TaskDetail Find(int id); void InsertOrUpdate(TaskDetail taskdetail); void Delete(int id); void Save(); }
上面我们通过Entity Framework实现了数据的操作，接下来，让我们控制器CalendarController的API的方法吧！
/// <summary> /// The server api controller. /// </summary> public class CalendarController : ApiController { readonly ITaskDayRepository _taskDayRepository = new TaskDayRepository(); readonly TaskDetailRepository _taskDetailRepository = new TaskDetailRepository(); /// <summary> /// Gets the task details. /// </summary> /// <param name="id">The identifier.</param> /// <returns>A list of task detail.</returns> /// /api/Calendar/GetTaskDetails?id [HttpGet] public List<TaskDetail> GetTaskDetails(DateTime id) { var taskDay = _taskDayRepository.All.FirstOrDefault<TaskDay>(_ => _.Day == id); return taskDay != null ? taskDay.Tasks : new List<TaskDetail>(); } /// <summary> /// Saves the task. /// </summary> /// <param name="taskDetail">The task detail.</param> /// <returns></returns> /// /api/Calendar/SaveTask?taskDetail [HttpPost] public bool SaveTask(TaskDetail taskDetail) { var targetDay = new DateTime( taskDetail.Starts.Year, taskDetail.Starts.Month, taskDetail.Starts.Day); // Check new task or not. var day = _taskDayRepository.All.FirstOrDefault<TaskDay>(_ => _.Day == targetDay); if (null == day) { day = new TaskDay { Day = targetDay, Tasks = new List<TaskDetail>() }; _taskDayRepository.InsertOrUpdate(day); _taskDayRepository.Save(); taskDetail.ParentTaskId = day.Id; } else { taskDetail.ParentTaskId = day.Id; taskDetail.ParentTask = null; } _taskDetailRepository.InsertOrUpdate(taskDetail); _taskDetailRepository.Save(); return true; } /// <summary> /// Deletes the task. /// </summary> /// <param name="id">The identifier.</param> /// <returns></returns> /// /api/Calendar/DeleteTask?id [HttpDelete] public bool DeleteTask(int id) { try { _taskDetailRepository.Delete(id); _taskDetailRepository.Save(); return true; } catch (Exception) { return false; } } }
Knockout JS
上面，我们通过APS.NET MVC实现了服务端，接下来，我们通过Knockout JS实现客户端访问服务端，首先，我们在Script文件中创建day-calendar.js和day-calendar.knockout.bindinghandlers.js文件。
// The viem model type. var ViewModel = function () { var $this = this, d = new Date(); // Defines observable object, when the selectedDate value changed, will // change data bind in the view. $this.selectedDate = ko.observable(new Date(d.getFullYear(), d.getMonth(), d.getDate())); $this.selectedTaskDetails = ko.observable(new TaskDetails(d)); // A serial of observable object observableArray. $this.dateDetails = ko.observableArray(); $this.appointments = ko.observableArray(); // Init date details list. $this.initializeDateDetails = function () { $this.dateDetails.removeAll(); for (var i = 0; i < 24; i++) { var dt = $this.selectedDate(); $this.dateDetails.push({ count: i, TaskDetails: new GetTaskHolder(i, dt) }); } }; // Call api to get task details. $this.getTaskDetails = function (date) { var dt = new Date(date.getFullYear(), date.getMonth(), date.getDate()), uri = "/api/Calendar/GetTaskDetails"; // Deprecation Notice: The jqXHR.success(), jqXHR.error(), and jqXHR.complete() callbacks are deprecated as of jQuery 1.8. // To prepare your code for their eventual removal, use jqXHR.done(), jqXHR.fail(), and jqXHR.always() instead. // Reference: https://api.jquery.com/jQuery.ajax/ $.get(uri, ‘id=‘ + dt.getFullYear() + ‘-‘ + (dt.getMonth() + 1) + ‘-‘ + dt.getDate() ).done(function(data) { $this.appointments.removeAll(); $(data).each(function(i, item) { $this.appointments.push(new Appointment(item, i)); }); }).error(function(data) { alert("Failed to retrieve tasks from server."); }); }; };
上面，我们定义了ViewModel类型，并且在其中定义了一系列的方法。
- selectedDate：获取用户在日历控件中选择的日期。
- selectedTaskDetails：获取用户选择中TaskDetail对象。
- dateDetails：定义监控数组，它保存了24个时间对象。
- appointments：定义监控数组保存每个TaskDetail对象。
接下来，需要获取用户点击日历控件的操作，我们通过方法ko.bindingHandlers()自定义事件处理方法，具体定义如下：
// Binding event handler with date picker. ko.bindingHandlers.datepicker = { init: function (element, valueAccessor, allBindingsAccessor) { // initialize datepicker with some optional options var options = allBindingsAccessor().datepickerOptions || {}; $(element).datepicker(options); // when a user changes the date, update the view model ko.utils.registerEventHandler(element, "changeDate", function (event) { var value = valueAccessor(); // Determine if an object property is ko.observable if (ko.isObservable(value)) { value(event.date); } }); }, update: function (element, valueAccessor) { var widget = $(element).data("datepicker"); //when the view model is updated, update the widget if (widget) { widget.date = ko.utils.unwrapObservable(valueAccessor()); widget.setValue(); } } };
上面，我们定义了日历控件的事件处理方法，当用户选择日历中的日期时，我们获取当前选择的日期绑定到界面上，具体定义如下：
<!-- Selected time control --> <input id="selectStartDate" data-bind="datepicker: Starts" type="text" class="span12" />
上面，我们在Html元素中绑定了datepicker事件处理方法并且把Starts值显示到input元素中。
图4 日历控件
接下来，我们定义Time picker事件处理方法，当用户时间时获取当前选择的时间绑定到界面上，具体定义如下：
// Binding event handler with time picker. ko.bindingHandlers.timepicker = { init: function (element, valueAccessor, allBindingsAccessor) { //initialize timepicker var options = $(element).timepicker(); //when a user changes the date, update the view model ko.utils.registerEventHandler(element, "changeTime.timepicker", function (event) { var value = valueAccessor(); if (ko.isObservable(value)) { value(event.time.value); } }); }, update: function (element, valueAccessor) { var widget = $(element).data("timepicker"); //when the view model is updated, update the widget if (widget) { var time = ko.utils.unwrapObservable(valueAccessor()); widget.setTime(time); } } };
同样，我们把时间值绑定页面元素中，具体定义如下：
<!-- Time picker value--> <input id="selectStartTime" data-bind="timepicker: StartTime" class="span8" type="text" />
现在，我们已经实现获取用户的输入，接下来需要把用户输入的任务信息数据保存到数据库中，那么我们将通过$.ajax()方法调用API接口，首先我们在day-calendar.js文件中定义类型TaskDetails，具体定义如下：
// TaskDetails type. var TaskDetails = function (date) { var $this = this; $this.Id = ko.observable(); $this.ParentTask = ko.observable(); $this.Title = ko.observable("New Task"); $this.Details = ko.observable(); $this.Starts = ko.observable(new Date(new Date(date).setMinutes(0))); $this.Ends = ko.observable(new Date(new Date(date).setMinutes(59))); // Gets start time when starts changed. $this.StartTime = ko.computed({ read: function () { return $this.Starts().toLocaleTimeString("en-US"); }, write: function (value) { if (value) { var dt = new Date($this.Starts().toDateString() + " " + value); $this.Starts(new Date($this.Starts().getFullYear(), $this.Starts().getMonth(), $this.Starts().getDate(), dt.getHours(), dt.getMinutes())); } } }); // Gets end time when ends changed. $this.EndTime = ko.computed({ read: function () { return $this.Ends().toLocaleTimeString("en-US"); }, write: function (value) { if (value) { var dt = new Date($this.Ends().toDateString() + " " + value); $this.Ends(new Date($this.Ends().getFullYear(), $this.Ends().getMonth(), $this.Ends().getDate(), dt.getHours(), dt.getMinutes())); } } }); $this.btnVisibility = ko.computed(function () { if ($this.Id() > 0) { return "visible"; } else { return "hidden"; } }); $this.Save = function (data) { // http://knockoutjs.com/documentation/plugins-mapping.html var taskDetails = ko.mapping.toJS(data); taskDetails.Starts = taskDetails.Starts.toDateString(); taskDetails.Ends = taskDetails.Ends.toDateString(); $.ajax({ url: "/api/Calendar/SaveTask", type: "POST", contentType: "text/json", data: JSON.stringify(taskDetails) }).done(function () { $("#currentTaskModal").modal("toggle"); vm.getTaskDetails(vm.selectedDate()); }).error(function () { alert("Failed to Save Task"); }); }; $this.Delete = function (data) { $.ajax({ url: "/api/Calendar/" + data.Id(), type: "DELETE", }).done(function () { $("#currentTaskModal").modal("toggle"); vm.getTaskDetails(vm.selectedDate()); }).error(function () { alert("Failed to Delete Task"); }); }; $this.Cancel = function (data) { $("#currentTaskModal").modal("toggle"); }; };
我们在TaskDetails类型中定义方法Save()和Delete()，我们看到Save()方法通过$.ajax()调用接口“/api/Calendar/SaveTask” 保存数据，这里要注意的是我们把TaskDetails对象序列化成JSON格式数据，然后调用SaveTask()保存数据。
现在，我们已经实现了页面绑定用户的输入，然后由Knockout JS访问Web API接口，对数据库进行操作；接着需要对程序界面进行调整，我们在项目中添加bootstrap-responsive.css和bootstrap.css文件引用，接下来，我们在的BundleConfig中指定需要加载的Javascript和CSS文件，具体定义如下：
/// <summary> /// Compress JS and CSS file. /// </summary> public class BundleConfig { /// <summary> /// Registers the bundles. /// </summary> /// <param name="bundles">The bundles.</param> public static void RegisterBundles(BundleCollection bundles) { bundles.Add(new ScriptBundle("~/bundles/jquery").Include( "~/Scripts/jquery-{version}.js")); bundles.Add(new ScriptBundle("~/bundles/bootstrap").Include( "~/Scripts/bootstrap.js", "~/Scripts/html5shiv.js")); bundles.Add(new ScriptBundle("~/bundles/jqueryval").Include( "~/Scripts/jquery.unobtrusive*", "~/Scripts/jquery.validate*")); bundles.Add(new ScriptBundle("~/bundles/knockout").Include( "~/Scripts/knockout-{version}.js")); bundles.Add(new StyleBundle("~/Styles/bootstrap/css").Include( "~/Content/bootstrap-responsive.css", "~/Content/bootstrap.css")); bundles.Add(new ScriptBundle("~/bundles/jquerydate").Include( "~/Scripts/datepicker/bootstrap-datepicker.js", //"~/Scripts/datepicker/locales/bootstrap-datepicker.zh-CN.js", "~/Scripts/timepicker/bootstrap-timepicker.min.js", "~/Scripts/moment.js")); bundles.Add(new ScriptBundle("~/bundles/app").Include( "~/Scripts/app/day-calendar*")); bundles.Add(new StyleBundle("~/Styles/jquerydate").Include( "~/Content/datepicker/datepicker.css", "~/Content/timepicker/bootstrap-timepicker.css")); } }
图5 任务管理器Demo
1.1.3 总结
我们通过一个任务管理程序的实现介绍了Knockout JS和Web API的结合使用，服务端我们通过Entity Framework对数据进行操作，然后使用API控制器开放接口让客户端访问，然后我们使用Knockout JS的数据绑定和事件处理方法实现了动态的页面显示，最后，我们使用了BootStrap CSS美化了一下程序界面。
本文仅仅是介绍了Knockout JS和Web API的结合使用，如果大家想进一步学习，参考如下链接。
参考
- https://github.com/dotnetcurry/ko-calendar-dncmag-08
- http://blogs.msdn.com/b/webdev/archive/2013/11/18/announcing-release-of-asp-net-and-web-tools-2013-1-for-visual-studio-2012.aspx
- http://code.tutsplus.com/tutorials/into-the-ring-with-knockout-js--net-21239
- http://code.tutsplus.com/series/into-the-ring-with-knockoutjs--net-22038
- http://www.asp.net/web-api/overview/creating-web-apis/using-web-api-with-entity-framework/using-web-api-with-entity-framework,-part-5