Introduction

In this article, I will demonstrate how we can create sample CRUD (Create, Read, Update, Delete) operations using ASP.NET, Web API2, and Knockout.js. I hope you will like this.

Prerequisites

First, you must have Visual Studio 2015 (.NET Framework 4.5.2) and a SQL Server.

In this post, we are going to:

• Create an MVC application.
• Configure an Entity framework ORM to connect to a database.
• Implementing all the HTTP Services needed.
• Call Services using Knockout.js.

SQL Database Part

Here, you will find the scripts to create your database and table.

Create Database

USE [master]
GO

/****** Object:  Database [DBCustomer]    Script Date: 3/4/2017 3:23:57 PM ******/
CREATE DATABASE [DBCustomer]
 CONTAINMENT = NONE
 ON  PRIMARY 
( NAME = N'DBCustomer', FILENAME = N'c:\Program Files (x86)\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\DATA\DBCustomer.mdf' , SIZE = 3072KB , MAXSIZE = UNLIMITED, FILEGROWTH = 1024KB )
 LOG ON 
( NAME = N'DBCustomer_log', FILENAME = N'c:\Program Files (x86)\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\DATA\DBCustomer_log.ldf' , SIZE = 1024KB , MAXSIZE = 2048GB , FILEGROWTH = 10%)
GO

ALTER DATABASE [DBCustomer] SET COMPATIBILITY_LEVEL = 110
GO

IF (1 = FULLTEXTSERVICEPROPERTY('IsFullTextInstalled'))
begin
EXEC [DBCustomer].[dbo].[sp_fulltext_database] @action = 'enable'
end
GO

ALTER DATABASE [DBCustomer] SET ANSI_NULL_DEFAULT OFF 
GO

ALTER DATABASE [DBCustomer] SET ANSI_NULLS OFF 
GO

ALTER DATABASE [DBCustomer] SET ANSI_PADDING OFF 
GO

ALTER DATABASE [DBCustomer] SET ANSI_WARNINGS OFF 
GO

ALTER DATABASE [DBCustomer] SET ARITHABORT OFF 
GO

ALTER DATABASE [DBCustomer] SET AUTO_CLOSE OFF 
GO

ALTER DATABASE [DBCustomer] SET AUTO_CREATE_STATISTICS ON 
GO

ALTER DATABASE [DBCustomer] SET AUTO_SHRINK OFF 
GO

ALTER DATABASE [DBCustomer] SET AUTO_UPDATE_STATISTICS ON 
GO

ALTER DATABASE [DBCustomer] SET CURSOR_CLOSE_ON_COMMIT OFF 
GO

ALTER DATABASE [DBCustomer] SET CURSOR_DEFAULT  GLOBAL 
GO

ALTER DATABASE [DBCustomer] SET CONCAT_NULL_YIELDS_NULL OFF 
GO

ALTER DATABASE [DBCustomer] SET NUMERIC_ROUNDABORT OFF 
GO

ALTER DATABASE [DBCustomer] SET QUOTED_IDENTIFIER OFF 
GO

ALTER DATABASE [DBCustomer] SET RECURSIVE_TRIGGERS OFF 
GO

ALTER DATABASE [DBCustomer] SET  DISABLE_BROKER 
GO

ALTER DATABASE [DBCustomer] SET AUTO_UPDATE_STATISTICS_ASYNC OFF 
GO

ALTER DATABASE [DBCustomer] SET DATE_CORRELATION_OPTIMIZATION OFF 
GO

ALTER DATABASE [DBCustomer] SET TRUSTWORTHY OFF 
GO

ALTER DATABASE [DBCustomer] SET ALLOW_SNAPSHOT_ISOLATION OFF 
GO

ALTER DATABASE [DBCustomer] SET PARAMETERIZATION SIMPLE 
GO

ALTER DATABASE [DBCustomer] SET READ_COMMITTED_SNAPSHOT OFF 
GO

ALTER DATABASE [DBCustomer] SET HONOR_BROKER_PRIORITY OFF 
GO

ALTER DATABASE [DBCustomer] SET RECOVERY SIMPLE 
GO

ALTER DATABASE [DBCustomer] SET  MULTI_USER 
GO

ALTER DATABASE [DBCustomer] SET PAGE_VERIFY CHECKSUM  
GO

ALTER DATABASE [DBCustomer] SET DB_CHAINING OFF 
GO

ALTER DATABASE [DBCustomer] SET FILESTREAM( NON_TRANSACTED_ACCESS = OFF ) 
GO

ALTER DATABASE [DBCustomer] SET TARGET_RECOVERY_TIME = 0 SECONDS 
GO

ALTER DATABASE [DBCustomer] SET  READ_WRITE 
GO

Create Table

USE [DBCustomer]
GO

/****** Object:  Table [dbo].[Customer]    Script Date: 3/4/2017 3:24:49 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[Customer](
[CustID] [int] IDENTITY(1,1) NOT NULL,
[FirstName] [varchar](50) NULL,
[LastName] [varchar](50) NULL,
[Email] [varchar](50) NULL,
[Country] [varchar](50) NULL,
 CONSTRAINT [PK_Customer] PRIMARY KEY CLUSTERED 
(
[CustID] 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

SET ANSI_PADDING OFF
GO

Create Your MVC application

Open Visual Studio and select File >> New Project.

The "New Project" window will pop up. Select ASP.NET Web Application (.NET Framework), name your project, and click OK.

Next, a new window will pop up for selecting the template. We are going choose Web API template and click OK.

After creating our project, we are going to add the ADO.NET Entity Data Model.

Adding ADO.NET Entity Data Model

To add the ADO.NET Entity Framework, right click on the project name, click Add > Add New Item. A dialog box will pop up. Inside this box, select Visual C# Data then ADO.NET Entity Data Model, and enter a name for your Dbcontext model, such as CustomerModel, and finally click Add.

Next, we need to choose model contain for the EF Designer from the database.

As you can see below, we need to select a server name, then, via a drop down list, connect it to a database panel. You should choose your database name. Finally, click OK.

Now, the Entity Data Model Wizard window will pop up for choosing an object which we need to use. In our case, we are going to choose Customers table and click Finish. Finally, we see that the EDMX model generates a Customer class.

Create a Controller

Now, we are going to create a controller. Right click on the controllers folder > Add > Controller> selecting Web API 2 Controller with actions using Entity Framework > click Add.

In the snapshot given below, we are providing three important parameters:

• Model class: Customer represents the entity that should be used for CRUD operations.
• Data context class: used to establish a connection with the database.
• Finally, we need to name our controller (in this case Customers Controller).

As we already know, Web API is a framework that makes it easy to build HTTP services that reach a broad range of clients including browsers and mobile devices.

It has four methods:

• Get is used to select data.
• Post is used to create or insert data.
• Put is used to update data.
• Delete is used to delete data.

CustomersController.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;
using System.Web.Http.Description;
using CustomerApp;
using CustomerApp.Models;

namespace CustomerApp.Controllers
{
    public class CustomersController : ApiController
    {
        //DbContext
        private DBCustomerEntities db = new DBCustomerEntities();

        // GET: api/Customers
        public IQueryable<Customer> GetCustomers()
        {
            return db.Customers;
        }



        // PUT: api/Customers/5
        [ResponseType(typeof(void))]
        public IHttpActionResult PutCustomer(int id, Customer customer)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != customer.CustID)
            {
                return BadRequest();
            }

            db.Entry(customer).State = EntityState.Modified;

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!CustomerExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return StatusCode(HttpStatusCode.NoContent);
        }

        // POST: api/Customers
        [ResponseType(typeof(Customer))]
        public IHttpActionResult PostCustomer(Customer customer)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            db.Customers.Add(customer);
            db.SaveChanges();

            return CreatedAtRoute("DefaultApi", new { id = customer.CustID }, customer);
        }

        // DELETE: api/Customers/5
        [ResponseType(typeof(Customer))]
        public IHttpActionResult DeleteCustomer(int id)
        {
            Customer customer = db.Customers.Find(id);
            if (customer == null)
            {
                return NotFound();
            }

            db.Customers.Remove(customer);
            db.SaveChanges();

            return Ok(customer);
        }
        //GetCustomerByCountry: returns list of nb customers by country 
       [Route("Customers/GetCustomerByCountry")]
        public IList<CustomerData> GetCustomerByCountry()
        {
            List<string> countryList = new List<string>() { "Morocco", "India", "USA", "Spain" };
            IEnumerable<Customer> customerList = db.Customers;
            List <CustomerData> result = new List<CustomerData>();

            foreach (var item in countryList)
            {
                int nbCustomer = customerList.Where(c => c.Country == item).Count();
                result.Add(new CustomerData()
                {
                    CountryName = item,
                    value = nbCustomer
                });
            }

            if(result != null)
            {
                return result;
            }

            return null;
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                db.Dispose();
            }
            base.Dispose(disposing);
        }

        private bool CustomerExists(int id)
        {
            return db.Customers.Count(e => e.CustID == id) > 0;
        }
    }
}

Calling Services Using Knockout.js

First of all, we need to install Knockout.js. From the solution explorer panel, right click on references > Manage NuGet Packages…

Next, type Knockout.js in search text box, select the first line as below and click Install.

Now, we need to add a new JS file. Right click on scripts folder > Add > JavaScript File.

App.js

Here, we create our view model that contains all the business logic. Then, we bind it with ko.applyBindings(new viewModel()) which enables us to activate Knockout for the current HTML document.

As you can see in the below code, KO provides observables to bind to the model.

• Ko.observable(): used to define model properties which can notify the changes and update the model automatically.
• Ko.observableArray([]): used to bind list of elements.

var ViewModel = function () {

    var self = this;
    self.CustID = ko.observable();
    self.FirstName = ko.observable();
    self.LastName = ko.observable();
    self.Email = ko.observable();
    self.CountryList = ko.observableArray(['Morocco', 'India', 'USA', 'Spain']);
    self.Country = ko.observable();

    self.customerList = ko.observableArray([]);

    var CustomerUri = '/api/Customers/';



    function ajaxFunction(uri, method, data) {

        //self.errorMessage('');

        return $.ajax({

            type: method,
            url: uri,
            dataType: 'json',
            contentType: 'application/json',
            data: data ? JSON.stringify(data) : null

        }).fail(function (jqXHR, textStatus, errorThrown) {
            alert('Error : ' + errorThrown);
        });
    }


    // Clear Fields
    self.clearFields = function clearFields() {
        self.FirstName('');
        self.LastName('');
        self.Email('');
        self.Country('');
    }

    //Add new Customer
    self.addNewCustomer = function addNewCustomer(newCustomer) {

        var CustObject = {
            CustID: self.CustID(),
            FirstName: self.FirstName(),
            LastName: self.LastName(),
            Email: self.Email(),
            Country: self.Country()
        };
        ajaxFunction(CustomerUri, 'POST', CustObject).done(function () {

            self.clearFields();
            alert('Customer Added Successfully !');
            getCustomerList()
        });
    }

    //Get Customer List
    function getCustomerList() {
        $("div.loadingZone").show();
        ajaxFunction(CustomerUri, 'GET').done(function (data) {
            $("div.loadingZone").hide();
            self.customerList(data);
        });

    }

    //Get Detail Customer
    self.detailCustomer = function (selectedCustomer) {

        self.CustID(selectedCustomer.CustID);
        self.FirstName(selectedCustomer.FirstName);
        self.LastName(selectedCustomer.LastName);
        self.Email(selectedCustomer.Email);
        self.Country(selectedCustomer.Country);

        $('#Save').hide();
        $('#Clear').hide();

        $('#Update').show();
        $('#Cancel').show();

    };

    self.cancel = function () {

        self.clearFields();

        $('#Save').show();
        $('#Clear').show();

        $('#Update').hide();
        $('#Cancel').hide();
    }

    //Update Customer
    self.updateCustomer = function () {

        var CustObject = {
            CustID: self.CustID(),
            FirstName: self.FirstName(),
            LastName: self.LastName(),
            Email: self.Email(),
            Country: self.Country()
        };

        ajaxFunction(CustomerUri + self.CustID(), 'PUT', CustObject).done(function () {
            alert('Customer Updated Successfully !');
            getCustomerList();
            self.cancel();
        });
    }

    //Delete Customer
    self.deleteCustomer = function (customer) {

        ajaxFunction(CustomerUri + customer.CustID, 'DELETE').done(function () {

            alert('Customer Deleted Successfully');
            getCustomerList();
        })

    }

    //Chart Line function used to display a chart which represents nb of customers by country
    function chartLine() {

        ajaxFunction('http://localhost:50706/Customers/GetCustomerByCountry', 'GET').done(function (result) {
            console.log(result);
            Morris.Line({
                element: 'line-chart',
                data: result,
                xkey: 'CountryName',
                // A list of names of data record attributes that contain y-values.
                ykeys: ['value'],
                // Labels for the ykeys -- will be displayed when you hover over the
                // chart.
                labels: ['Value'],

                parseTime: false
            });


        });

    };

    chartLine();
    getCustomerList();

};

ko.applyBindings(new ViewModel());

Now, from the solution explorer panel, we are going to add an index.html file as shown below.

Index.html

<!DOCTYPE html>
<html>
<head>

    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <title>.: Customer App :. Web API2 &Aacute; KnockOutJS</title>
<meta charset="utf-8" />

    <!-- CSS -->
    <link href="Content/bootstrap.min.css" rel="stylesheet" />
    <link href="https://cdn.oesmith.co.uk/morris-0.5.1.css" rel="stylesheet" />



</head>
<body>

    <nav class="navbar navbar-default navbar-fixed-top">

        <div class="container-fluid">

            <div class="navbar-header">
                <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                <a class="navbar-brand" href="#">WEB API2 - KnockOutJS</a>
            </div> <!-- END HEADER NAV -->

        </div> <!-- END CONTAINER -->

    </nav><!-- END NAV-->

    <div class="container" style="margin-top: 7%;">


        <div class="row">

            <div class="col-md-4">

                <!-- FORM -->
                <div class="panel panel-default">

                    <div class="panel-heading"> <span class="glyphicon glyphicon glyphicon-tag" aria-hidden="true"></span> <b>Add New Customer</b></div>
                    <div class="panel-body">

                        <form>

                            <div class="form-group" style="display:none;">
                                <label for="CustomerID">Customer ID</label>
                                <input type="text" id="CustomerID" class="form-control" data-bind="value:CustID" placeholder="Customer ID" />
                            </div><!-- END CUSTOMER ID -->

                            <div class="form-group">
                                <label for="FirstName">First Name</label>
                                <input type="text" id="FirstName" class="form-control" data-bind="value:FirstName" placeholder="First Name" />
                            </div><!-- END FIRST NAME -->

                            <div class="form-group">
                                <label for="LastName">Last Name</label>
                                <input type="text" id="LastName" class="form-control" data-bind="value: LastName" placeholder="Last Name" />
                            </div><!-- END LAST NAME -->

                            <div class="form-group">
                                <label for="Email">Email</label>
                                <input type="email" id="Email" class="form-control" data-bind="value: Email" placeholder="Email" />
                            </div> <!-- END EMAIL -->

                            <div class="form-group">
                                <label for="Country">Country</label>
                                <select class="form-control" data-bind="options: CountryList, value: Country, optionsCaption: 'Select your Country ...' " ></select>
                            </div> <!-- END COUNTRY -->


                            <button type="button" class="btn btn-success" data-bind="click: addNewCustomer" id="Save">
                                <span class="glyphicon  glyphicon glyphicon-floppy-disk" aria-hidden="true"></span> Save
                            </button>

                            <button type="button" class="btn btn-info" data-bind="click: clearFields" id="Clear">
                                <span class="glyphicon  glyphicon glyphicon-refresh" aria-hidden="true"></span> Clear
                            </button>

                            <button type="button" class="btn btn-warning" data-bind="click:updateCustomer " style="display:none;" id="Update">
                                <span class="glyphicon  glyphicon glyphicon-pencil" aria-hidden="true"></span> Update Customer
                            </button>

                            <button type="button" class="btn btn-default" data-bind="click:cancel " style="display:none;" id="Cancel">
                                <span class="glyphicon  glyphicon glyphicon-remove" aria-hidden="true"></span> Cancel
                            </button>

                        </form> <!-- END FORM -->


                    </div> <!-- END PANEL BODY-->

                </div><!-- END PANEL-->

            </div> <!-- END  col-md-4 -->

            <div class="col-md-8">

                <div class="panel panel-default">

                    <div class="panel-heading"><span class="glyphicon  glyphicon glyphicon-stats" aria-hidden="true"></span><b> Charting Customer</b>   </div>

                    <div class="panel-body">


                        <!-- <img src="images/Chart.png" style="width:60%; margin:6px 70px;" /> -->

                        <div id="line-chart" style="height: 300px;"></div><br/><br/>

                    </div> <!-- END PANEL-BODY-->

                </div> <!-- END PANEL-->

            </div> <!-- END col-md-8-->

        </div>

        <div class="row">

            <div class="col-md-12">

                <div class="panel panel-default">

                    <div class="panel-heading">
                        <span class="glyphicon  glyphicon glyphicon-zoom-in" aria-hidden="true"></span>  <b>Customer List </b>
                        <div class="loadingZone" style="color: #000; display:block; float:right; display:none;"> <img src="images/ajax-loader.gif" /> Refresh Data ...</div>
                    </div>

                    <div class="panel-body">

                        <table class="table table-hover">

                            <thead>
                                <tr>
                                    <th><span class="glyphicon glyphicon glyphicon-eye-open" aria-hidden="true"></span></th>
                                    <th>#</th>
                                    <th>First Name</th>
                                    <th>Last Name</th>
                                    <th>Email</th>
                                    <th>Country</th>
                                    <th></th>
                                </tr>
                            </thead> <!-- END THEAD -->

                            <tbody data-bind="foreach: customerList">

                                <tr>

                                    <td> <button type="button" class="btn btn-default btn-xs" data-bind="click: $root.detailCustomer"> <span class="glyphicon glyphicon glyphicon-eye-open" aria-hidden="true"></span></button> </td>
                                    <td> <span data-bind="text: CustID"></span> </td>
                                    <td> <span data-bind="text: FirstName"></span></td>
                                    <td> <span data-bind="text: LastName"></span></td>
                                    <td> <span data-bind="text: Email"></span> </td>
                                    <td> <span data-bind="text: Country"></span> </td>

                                    <td>

                                        <button type="button" class="btn btn-danger btn-xs">
                                            <span class="glyphicon glyphicon glyphicon-trash" aria-hidden="true" data-bind="click: $root.deleteCustomer"></span>
                                        </button>
                                    </td>

                                </tr>



                            </tbody> <!-- END TBODY -->

                        </table> <!-- END TABLE -->


                    </div>

                </div>

            </div>

        </div>
    </div> <!-- END CONTAINER-->

    <!-- JS -->
    <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
    <script src="Scripts/jquery-1.10.2.min.js"></script>
    <!-- Include all compiled plugins (below), or include individual files as needed -->
    <script src="Scripts/bootstrap.min.js"></script>
    <script src="Scripts/knockout-3.4.0.js"></script>

    <script src="https://cdnjs.cloudflare.com/ajax/libs/raphael/2.1.0/raphael-min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/morris.js/0.5.1/morris.min.js"></script>
    <!-- app.js-->
    <script src="Scripts/app.js"></script>

</body>
</html>

In order to exchange data between an HTML page and JavaScript file, Knockout.js offers various types of binding that should be used within the data-bind attribute.

• Click: represents a click event handler to call a JavaScript function.
• Value: represents the value binding with UI elements to the property defined into view Model.
• Text: represents the text value to the UI element.
• Foreach: used to fetch an array.

Now you can run your application. Don’t forget to change the URL address as below.

http://localhost:55192/index.html

Let’s see the output

That’s all! Please send your feedback and queries via the comments section.