I) Introduction
I have been browsing multiple sites to check if I could find a complete end to end tutorial or article upon CRUD operations using Knockout.JS and MVC 4. Unfortunately, all the ones I found were incomplete or had too short an explanation. In my last article we learned CRUD in ASP.NET web forms using MVC and EntityFramework. This article is the continuation to the same series. This article will be a kind of tutorial to explain how we can set up a Knockout.JS environment in an MVC4 application that is also capable of performing CRUD operations.
II) Our Road-Map
We’ll stick to our agenda of Learning Knockout.JS as follows,
- Part 1: Introduction to Knockout.js and CRUD Operations in Asp.Net Web Forms using Knockout.JS and Entity Framework.
- Part 2: Complete end to end CRUD operations using Knockout.JS and Entity Framework in MVC4 application.
III) Part2: Complete end to end CRUD operations using Knockout.JS and Entity Framework in MVC4 application
We’ll continue to discuss KO step by step in this article
- Creating an MVC application.
- Creating CRUD action methods using Entity Framework 5.
- Perform CRUD operations using MVC4 and Entity Framework 5
- Adding Knockout.JS to our MVC application.
- Perform CRUD operation using KO in our MVC 4 application.
Before we start, not going very deep into theory I would like to give an introduction to MVC,Entity Framework and Knockout.
IV) MVC
Model: The business entity on which the overall application operates. Many applications use a persistent storage mechanism (such as a database) to store data. MVC does not specifically mention the data access layer because it is understood to be encapsulated by the Model.
View: The user interface that renders the model into a form of interaction.
Controller: Handles a request from a view and updates the model that results a change in Model’s state.
To implement MVC in .NET we need mainly three classes (View, Controller and the Model).
V) Entity Framework
Let’s have a look on standard definition of Entity Framework given by Microsoft:
"The Microsoft ADO.NET Entity Framework is an Object/Relational Mapping (ORM) framework that enables developers to work with relational data as domain-specific objects, eliminating the need for most of the data access plumbing code that developers usually need to write. Using the Entity Framework, developers issue queries using LINQ, then retrieve and manipulate data as strongly typed objects. The Entity Framework’s ORM implementation provides services like change tracking, identity resolution, lazy loading, and query translation so that developers can focus on their application-specific business logic rather than the data access fundamentals."
In a simple language, Entity framework is an Object/Relational Mapping (ORM) framework. It is an enhancement to ADO.NET, an upper layer to ADO.NET that gives developers an automated mechanism for accessing & storing the data in the database.
Hope this gives a glimpse of an ORM and EntityFramework.
VI) Knockout.JS
Knockout.JS (KO) is basically a JS library that enables Declarative Bindings using an ‘Observable’ View Model on the client (browser) following observer pattern approach, enabling UI to bind and refresh itself automatically whenever the data bound is modified. Knockout.JS provides its own templating pattern that helps us to bind our view model data easily. KO works on MVVM pattern i.e. Model-View-View Model.
As the architecture is shown, Views interact with View Models in a two way binding manner i.e. when the model is changed it view updates itself and when view is updated, the model updates itself instantaneously.
KO provides 3 most important features like,
The whole idea of KO derives from these three major functionalities. KO also helps in developing Single page applications (SPA’s).SPA’s are out of the box new way of developing rich internet applications(RIA’s) in todays era.
VII) Application Architecture
The architecture is very much self explanatory. The application works on client-server model, where our MVC application or Web API application (not covered in this tutorial) will interact with EntityFramework layer on server side. Entity Framework layer will be responsible for data transactions with data base.
On client side we have HTML templates which will communicate with server through Ajax calls and the templates will be bind to data via JSON objects through knockout observables (already discussed in first part).
VIII) MVC Application
1. Step1: Create a data base named LearningKO and add a table named student to it, script of the table is as follows,
USE [LearningKO]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Student](
[StudentId] [nvarchar](10) NOT NULL,
[FirstName] [nvarchar](50) NULL,
[LastName] [nvarchar](50) NULL,
[Age] [int] NULL,
[Gender] [nvarchar](50) NULL,
[Batch] [nvarchar](50) NULL,
[Address] [nvarchar](50) NULL,
[Class] [nvarchar](50) NULL,
[School] [nvarchar](50) NULL,
[Domicile] [nvarchar](50) NULL,
CONSTRAINT [PK_Student] PRIMARY KEY CLUSTERED
(
[StudentId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
INSERT [dbo].[Student] ([StudentId], [FirstName], [LastName], [Age], [Gender], [Batch], [Address], [Class], [School], [Domicile]) VALUES (N'1', N'Akhil', N'Mittal', 28, N'Male', N'2006', N'Noida', N'Tenth', N'LFS', N'Delhi')
INSERT [dbo].[Student] ([StudentId], [FirstName], [LastName], [Age], [Gender], [Batch], [Address], [Class], [School], [Domicile]) VALUES (N'2', N'Parveen', N'Arora', 25, N'Male', N'2007', N'Noida', N'8th', N'DPS', N'Delhi')
INSERT [dbo].[Student] ([StudentId], [FirstName], [LastName], [Age], [Gender], [Batch], [Address], [Class], [School], [Domicile]) VALUES (N'3', N'Neeraj', N'Kumar', 38, N'Male', N'2011', N'Noida', N'10th', N'MIT', N'Outside Delhi')
INSERT [dbo].[Student] ([StudentId], [FirstName], [LastName], [Age], [Gender], [Batch], [Address], [Class], [School], [Domicile]) VALUES (N'4', N'Ekta', N'Mittal', 25, N'Female', N'2005', N' Noida', N'12th', N'LFS', N'Delhi')
- Step2: Open your Visual Studio (Visual Studio Version should be greater than or equal to 12) and add an MVC Internet application,
I have given it a name "KnockoutWithMVC4".
- Step3: You’ll get a full structured MVC application with default Home controller in the Controller folder. By default the entity framework is downloaded as a package inside application folder, but if not you can add entity framework package by right click the project, select manage nugget packages and search and install Entity Framework,
4. Step 4: Right click project file, select add new item and add ADO.NET entity data model. Follow the steps in the wizard as shown below,
Generate the model from the data base, select your server and LearningKO database name, the connection string will automatically be added to your Web.Config, name that connection string as LearningKOEntities.
Select tables to be added to the model. In our case it’s Student Table.
- Step5: Now add a new controller to the Controller folder, right click controller folder and add a controller named Student. Since we have already created our Datamodel, we can choose for an option where CRUD actions are created by chosen Entity Framework Datamodel,
- Name your controller as StudentController,
- from Scaffolding Options, select "MVC controller with read/write actions and views, using Entity Framework".
- Select Model class as Student, that lies in our solution.
- Select Data context class as
LearningKOEntities that is added to outr solution when we added EF data model.
- Select Razor as rendering engine for views.
- Click Advanced options, Select Layout or master page and select _Layout.cshtml from the shared folder.
- Step6: We see out student controller prepared with all the CRUD operation actions as shown below,
7. using System;
8. using System.Collections.Generic;
9. using System.Data;
10. using System.Data.Entity;
11. using System.Linq;
12. using System.Web;
13. using System.Web.Mvc;
14.
15. namespace KnockoutWithMVC4.Controllers
16. {
17. public class StudentController : Controller
18. {
19. private LearningKOEntities db = new LearningKOEntities();
20.
21.
22.
23.
24. public ActionResult Index()
25. {
26. return View(db.Students.ToList());
27. }
28.
29.
30.
31.
32. public ActionResult Details(string id = null)
33. {
34. Student student = db.Students.Find(id);
35. if (student == null)
36. {
37. return HttpNotFound();
38. }
39. return View(student);
40. }
41.
42.
43.
44.
45. public ActionResult Create()
46. {
47. return View();
48. }
49.
50.
51.
52.
53. [HttpPost]
54. [ValidateAntiForgeryToken]
55. public ActionResult Create(Student student)
56. {
57. if (ModelState.IsValid)
58. {
59. db.Students.Add(student);
60. db.SaveChanges();
61. return RedirectToAction("Index");
62. }
63.
64. return View(student);
65. }
66.
67.
68.
69.
70. public ActionResult Edit(string id = null)
71. {
72. Student student = db.Students.Find(id);
73. if (student == null)
74. {
75. return HttpNotFound();
76. }
77. return View(student);
78. }
79.
80.
81.
82.
83. [HttpPost]
84. [ValidateAntiForgeryToken]
85. public ActionResult Edit(Student student)
86. {
87. if (ModelState.IsValid)
88. {
89. db.Entry(student).State = EntityState.Modified;
90. db.SaveChanges();
91. return RedirectToAction("Index");
92. }
93. return View(student);
94. }
95.
96.
97.
98.
99. public ActionResult Delete(string id = null)
100. {
101. Student student = db.Students.Find(id);
102. if (student == null)
103. {
104. return HttpNotFound();
105. }
106. return View(student);
107. }
108.
109.
110.
111.
112. [HttpPost, ActionName("Delete")]
113. [ValidateAntiForgeryToken]
114. public ActionResult DeleteConfirmed(string id)
115. {
116. Student student = db.Students.Find(id);
117. db.Students.Remove(student);
118. db.SaveChanges();
119. return RedirectToAction("Index");
120. }
121.
122. protected override void Dispose(bool disposing)
123. {
124. db.Dispose();
125. base.Dispose(disposing);
126. }
127. }
128. }
- 7. Step7: Open App_Start folder and, change the name of controller from Home to Student,
the code will become as,
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Student", action = "Index", id = UrlParameter.Optional }
);
}
- Step8: Now press F5 to run the application, and you’ll see the list of all students we added in to table Student while creating it is displayed. Since the CRUD operations are automatically written, we have action results for display list and other Edit, Delete and Create operations. Note that views for all the operations are created in Views Folder under Student Folder name.
Now you can perform all the operations on this list.
Since I have not provided any validation checks on model or creating an existing student id, the code may break, so I am calling Edit Action in create when we find that id already exists,
Now create new student ,
We see that the student is created successfully and added to the list,
In data base,
Similarly for Edit,
Change any field and press save.The change will be reflected in the list and data base,
For Delete,
Student Deleted.
And in database,
So, that’s it, our first job is completed i.e. to create an MVC application, and perform CRUD operations using Entity Framework 5. You can see that until now we have not written a single line of code. Yes that’s the magic of MVC and EF. Cheers!
IX) Knockout Application
Our first job is well done,now moving on to our primary target, i.e. KO. Since KO depends largely on MVVM pattern, we’ll take MVVM at client side, and use our controller to be as same just modified little bit for returning JSON logic. You can learn about MVVM pattern and KO theory in first part of this article series.
- Step1:
JQuery and Knockout.js files are very important to be in the solution’s script folder. Check to them and if you do not find them, then add the packages for jQuery and Knockout, in the same fashion as you added Entity Framework.Right click project, select "Manage nugget packages" and search for jQuery then install it , then search for knockout package and install it,
- Step2: Right click Scripts folder and a folder named ViewModel.Add four js files to that folder, and name them as CreateVM.js, EditVM.js, DeleteVM.js and StudentListVM.js respectively. These are View Model files added to communicate to Controller and render our View templates.
- Step3: Add some code to CreateVm.js as,
var urlPath = window.location.pathname;
$(function () {
ko.applyBindings(CreateVM);
});
var CreateVM = {
Domiciles: ko.observableArray(['Delhi', 'Outside Delhi']),
Genders: ko.observableArray(['Male', 'Female']),
Students: ko.observableArray([]),
StudentId: ko.observable(),
FirstName: ko.observable(),
LastName: ko.observable(),
Age: ko.observable(),
Batch: ko.observable(),
Address: ko.observable(),
Class: ko.observable(),
School: ko.observable(),
Domicile: ko.observable(),
Gender: ko.observable(),
SaveStudent: function () {
$.ajax({
url: '/Student/Create',
type: 'post',
dataType: 'json',
data: ko.toJSON(this),
contentType: 'application/json',
success: function (result) {
},
error: function (err) {
if (err.responseText == "Creation Failed")
{ window.location.href = '/Student/Index/'; }
else {
alert("Status:"+err.responseText);
window.location.href = '/Student/Index/';;
}
},
complete: function () {
window.location.href = '/Student/Index/';
}
});
}
};
On document load we apply bindings for CreateVM, then inside the view model method we initialize the observables to properties of Student, that will be bind to respective view.You can read more about observables in KO in first part of the series. There is a save function, that sends an ajax request to Student Controller’s Create method, and gets string result. data: ko.toJSON(this), means sending the object in JSON format to controller method.
Student/Create Controller Method
Modify the code of controller method of Create, to return JSON to the caller. The HTML templates bound with objects are actually bound to json properties, set in the methods of view model using Knockout Observables.
The work on observer pattern, so that when model is updated the views automatically gets updated and when views get updated the models update itself, this is called two way binding.
Controller Code
[HttpPost]
public string Create(Student student)
{
if (ModelState.IsValid)
{
if (!StudentExists(student))
db.Students.Add(student);
else
return Edit(student);
db.SaveChanges();
return "Student Created";
}
return "Creation Failed";
}
View Code
Change the code of the already created views to work with KO,
For create.cshtml,
<h2>Create</h2>
<fieldset>
<legend>Create Student</legend>
<div class="editor-label">
Student id
</div>
<div class="editor-field">
<input data-bind="value: StudentId" />
</div>
<div class="editor-label">
First Name
</div>
<div class="editor-field">
<input data-bind="value: FirstName" />
</div>
<div class="editor-label">
Last Name
</div>
<div class="editor-field">
<input data-bind="value: LastName" />
</div>
<div class="editor-label">
Age
</div>
<div class="editor-field">
<input data-bind="value: Age" />
</div>
<div class="editor-label">
Gender
</div>
<div class="editor-field">
<select data-bind="options: Genders, value: Gender, optionsCaption: 'Select Gender...'"></select>
</div>
<div class="editor-label">
Batch
</div>
<div class="editor-field">
<input data-bind="value: Batch" />
</div>
<div class="editor-label">
Address
</div>
<div class="editor-field">
<input data-bind="value: Address" />
</div>
<div class="editor-label">
Class
</div>
<div class="editor-field">
<input data-bind="value: Class" />
</div>
<div class="editor-label">
School
</div>
<div class="editor-field">
<input data-bind="value: School" />
</div>
<div class="editor-label">
Domicile
</div>
<div class="item ">
<select data-bind="options: Domiciles, value: Domicile, optionsCaption: 'Select Domicile...'"></select>
</div>
<p>
<button type="button" data-bind="click: SaveStudent">Save Student To Database</button>
</p>
</fieldset>
<div>
<a href="@Url.Action("Index", "Student")" >Back to List</a>
</div>
@section Scripts {
@Scripts.Render("~/Scripts/ViewModels/CreateVM.js")
}
You can see I have used data-bind attribute of HTML5 to bind the View elements to View Models properties like data-bind="value: StudentId" , the same applies to all the editable elements. Click button is bound to SaveStudent method of view model.
At the end of the page we have registered the CreateVM.js view model for this particular view by
@section Scripts {
@Scripts.Render("~/Scripts/ViewModels/CreateVM.js")
}
Tag.
- Step3: We do the same set of operations for all the views, View models and Controller method, the code is as below,
For Edit
View Model
Code added in StudentListVM for Edit View Model, since it only perform get when it loads.
Controller methods
public ActionResult Edit(string id=null)
{
Student student = db.Students.Find(id);
if (student == null)
{
return null;
}
JavaScriptSerializer serializer = new JavaScriptSerializer();
ViewBag.InitialData = serializer.Serialize(student);
return View();
}
[HttpPost]
public string Edit(Student student)
{
if (ModelState.IsValid)
{
db.Entry(student).State = EntityState.Modified;
db.SaveChanges();
return "Student Edited";
}
return "Edit Failed";
}
View
<h2>Edit</h2>
<fieldset>
<legend>Edit Student</legend>
<div class="editor-label">
Student id
</div>
<div class="editor-field">
<input data-bind="value: StudentId" readonly="readonly" />
</div>
<div class="editor-label">
First Name
</div>
<div class="editor-field">
<input data-bind="value: FirstName" />
</div>
<div class="editor-label">
Last Name
</div>
<div class="editor-field">
<input data-bind="value: LastName" />
</div>
<div class="editor-label">
Age
</div>
<div class="editor-field">
<input data-bind="value: Age" />
</div>
<div class="editor-label">
Gender
</div>
<div class="editor-field">
<select data-bind="options: Genders, value: Gender, optionsCaption: 'Select Gender...'"></select>
</div>
<div class="editor-label">
Batch
</div>
<div class="editor-field">
<input data-bind="value: Batch" />
</div>
<div class="editor-label">
Address
</div>
<div class="editor-field">
<input data-bind="value: Address" />
</div>
<div class="editor-label">
Class
</div>
<div class="editor-field">
<input data-bind="value: Class" />
</div>
<div class="editor-label">
School
</div>
<div class="editor-field">
<input data-bind="value: School" />
</div>
<div class="editor-label">
Domicile
</div>
<div class="editor-field">
<select data-bind="options: Domiciles, value: Domicile, optionsCaption: 'Select Domicile...'"></select>
</div>
<p>
<button type="button" data-bind="click: SaveStudent">Save Student To Database</button>
</p>
</fieldset>
<div>
<a href="@Url.Action("Index", "Student")">Back to List</a>
</div>
@section Scripts {
<script>
$(function () {
ko.applyBindings(EditVM);
});
var initialData = '@Html.Raw(ViewBag.InitialData)';
var parsedJSON = $.parseJSON(initialData);
var EditVM = {
Domiciles: ko.observableArray(['Delhi', 'Outside Delhi']),
Genders: ko.observableArray(['Male', 'Female']),
Students: ko.observableArray([]),
StudentId: ko.observable(parsedJSON.StudentId),
FirstName: ko.observable(parsedJSON.FirstName),
LastName: ko.observable(parsedJSON.LastName),
Age: ko.observable(parsedJSON.Age),
Batch: ko.observable(parsedJSON.Batch),
Address: ko.observable(parsedJSON.Address),
Class: ko.observable(parsedJSON.Class),
School: ko.observable(parsedJSON.School),
Domicile: ko.observable(parsedJSON.Domicile),
Gender: ko.observable(parsedJSON.Gender),
SaveStudent: function () {
$.ajax({
url: '/Student/Edit',
type: 'post',
dataType: 'json',
data: ko.toJSON(this),
contentType: 'application/json',
success: function (result) {
},
error: function (err) {
if (err.responseText == "Creation Failed")
{ window.location.href = '/Student/Index/'; }
else {
alert("Status:" + err.responseText);
window.location.href = '/Student/Index/';;
}
},
complete: function () {
window.location.href = '/Student/Index/';
}
});
}
};
</script>
}
For Delete
View Model
Code added in StudentListVM for Edit View Model, since it only perform get when it loads.
Controller methods
public ActionResult Delete(string id = null)
{
Student student = db.Students.Find(id);
if (student == null)
{
return null;
}
JavaScriptSerializer serializer = new JavaScriptSerializer();
ViewBag.InitialData = serializer.Serialize(student);
return View();
}
[HttpPost]
public string Delete(Student student)
{
Student studentDetail = db.Students.Find(student.StudentId);
db.Students.Remove(studentDetail);
db.SaveChanges();
return "Student Deleted";
}
View
@model KnockoutWithMVC4.Student
@{
ViewBag.Title = "Delete";
}
<h2>Delete Student</h2>
<h3>Are you sure you want to delete this?</h3>
<fieldset>
<legend>Delete</legend>
<div class="display-label">
Student Id
</div>
<div class="display-field">
<input data-bind="value: StudentId" />
</div>
<div class="display-label">
First Name
</div>
<div class="display-field">
<input data-bind="value: FirstName" />
</div>
<div class="display-label">
Last Name
</div>
<div class="display-field">
<input data-bind="value: LastName" />
</div>
<div class="display-label">
Age
</div>
<div class="display-field">
<input data-bind="value: Age" />
</div>
<div class="display-label">
Gender
</div>
<div class="display-field">
<input data-bind="value: Gender" />
</div>
<div class="display-label">
Batch
</div>
<div class="display-field">
<input data-bind="value: Batch" />
</div>
<div class="display-label">
Address
</div>
<div class="display-field">
<input data-bind="value: Address" />
</div>
<div class="display-label">
Class
</div>
<div class="display-field">
<input data-bind="value: Class" />
</div>
<div class="display-label">
School
</div>
<div class="display-field">
<input data-bind="value: School" />
</div>
<div class="display-label">
Domicile
</div>
<div class="display-field">
<input data-bind="value: Domicile" />
</div>
</fieldset>
<p>
<button type="button" data-bind="click: DeleteStudent">Delete Student</button> |
<a href="@Url.Action("Index", "Student")">Back to List</a>
</p>
@section Scripts {
<script>
$(function () {
ko.applyBindings(DeleteVM);
});
var initialData = '@Html.Raw(ViewBag.InitialData)';
var parsedJSON = $.parseJSON(initialData);
var DeleteVM = {
Domiciles: ko.observableArray(['Delhi', 'Outside Delhi']),
Genders: ko.observableArray(['Male', 'Female']),
Students: ko.observableArray([]),
StudentId: ko.observable(parsedJSON.StudentId),
FirstName: ko.observable(parsedJSON.FirstName),
LastName: ko.observable(parsedJSON.LastName),
Age: ko.observable(parsedJSON.Age),
Batch: ko.observable(parsedJSON.Batch),
Address: ko.observable(parsedJSON.Address),
Class: ko.observable(parsedJSON.Class),
School: ko.observable(parsedJSON.School),
Domicile: ko.observable(parsedJSON.Domicile),
Gender: ko.observable(parsedJSON.Gender),
DeleteStudent: function () {
$.ajax({
url: '/Student/Delete',
type: 'post',
dataType: 'json',
data: ko.toJSON(this),
contentType: 'application/json',
success: function (result) {
},
error: function (err) {
if (err.responseText == "Creation Failed")
{ window.location.href = '/Student/Index/'; }
else {
alert("Status:" + err.responseText);
window.location.href = '/Student/Index/';;
}
},
complete: function () {
window.location.href = '/Student/Index/';
}
});
}
};
</script>
}
For Index(To display list)
View Model
var urlPath = window.location.pathname;
$(function () {
ko.applyBindings(StudentListVM);
StudentListVM.getStudents();
});
var StudentListVM = {
Students: ko.observableArray([]),
getStudents: function () {
var self = this;
$.ajax({
type: "GET",
url: '/Student/FetchStudents',
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (data) {
self.Students(data);
},
error: function (err) {
alert(err.status + " : " + err.statusText);
}
});
},
};
self.editStudent = function (student) {
window.location.href = '/Student/Edit/' + student.StudentId;
};
self.deleteStudent = function (student) {
window.location.href = '/Student/Delete/' + student.StudentId;
};
function Students(data) {
this.StudentId = ko.observable(data.StudentId);
this.FirstName = ko.observable(data.FirstName);
this.LastName = ko.observable(data.LastName);
this.Age = ko.observable(data.Age);
this.Gender = ko.observable(data.Gender);
this.Batch = ko.observable(data.Batch);
this.Address = ko.observable(data.Address);
this.Class = ko.observable(data.Class);
this.School = ko.observable(data.School);
this.Domicile = ko.observable(data.Domicile);
}
Controller methods
public JsonResult FetchStudents()
{
return Json(db.Students.ToList(), JsonRequestBehavior.AllowGet);
}
View
@model IEnumerable<KnockoutWithMVC4.Student>
@{
ViewBag.Title = "Index";
}
<h2>Students List</h2>
<p>
<a href="@Url.Action("Create", "Student")" >Create Student</a>
</p>
<table>
<thead>
<tr>
<th>
Student Id
</th>
<th>
First Name
</th>
<th>
Last Name
</th>
<th>
Age
</th>
<th>
Gender
</th>
<th>
Batch
</th>
<th>
Address
</th>
<th>
Class
</th>
<th>
School
</th>
<th>
Domicile
</th>
<th></th>
</tr>
</thead>
<tbody data-bind="foreach: Students">
<tr>
<td data-bind="text: StudentId"></td>
<td data-bind="text: FirstName"></td>
<td data-bind="text: LastName"></td>
<td data-bind="text: Age"></td>
<td data-bind="text: Gender"></td>
<td data-bind="text: Batch"></td>
<td data-bind="text: Address"></td>
<td data-bind="text: Class"></td>
<td data-bind="text: School"></td>
<td data-bind="text: Domicile"></td>
<td>
<a data-bind="click: editStudent">Edit</a>
<a data-bind="click: deleteStudent">Delete</a>
</td>
</tr>
</tbody>
</table>
@section Scripts {
@Scripts.Render("~/Scripts/ViewModels/StudentListVM.js")
}
The return Json(db.Students.ToList(), JsonRequestBehavior.AllowGet); code returns the student object in json format, for binding to the view.
All set now, you can press F5 to run the application and we see, that application runs in the same manner as it executed before,
Now you can perform all the operations on this list.
Do not type anything else other than int for student id and Age, since validation checks are missing, they may cause error.
Now create new student ,
We see that the student is created successfully and added to the list,
In data base,
Similarly for Edit,
Change any field and press save.The change will be reflected in the list and data base,
For Delete,
Student Deleted.
And in database,
X) Knockout Attributes Glossary
. observable: Used to define model/entity properties. If these properties are bound with user interface and when value for these properties gets updated, automatically the UI elements bound with these properties will be updated with the new value instantaneously.
e.g. this.StudentId = ko.observable("1"); - => StudentId is the observable property. KO represent an object for the Knockout.js library.
The value of the observable is read as var id= this. StudentId ();
· observableArray: observableArray represents a collection of data elements which required notifications. It’s used to bind with the List kind of elements.
e.g this.Students = ko.observableArray([]);
· applyBindings: This is used to activate knockout for the current HTML document or a specific UI element in HTML document. The parameter for this method is the view-model which is defined in JavaScript. This ViewModel contains the observable, observableArray and various methods.
Various other types of binding are used in this article:
. click: Represents a click event handler added to the UI element so that JavaScript function is called.
. value: This represents the value binding with the UI element’s value property to the property defined into the ViewModel.
The value binding should be used with <input> , <select> , <textarea>
. visible: This is used to hide or unhide the UI element based upon the value passed to it’s binding.
. Text: This represent the text value of the parameter passed to the UI element.
XI) Conclusion
In this article of series Learning Knockout, we learned a lot of things about MVC, Entity Framework and Knockout.JS. We did practical hands on by creating a CRUD operations application too.
Therefore we can mark it as tasks done.
We’ll be covering more topics in my upcoming articles.
Note: few of the images in this article are taken via Google search.
Happy Coding :).
