Part 2 - How to implement Basic CRUD Functionality with the Entity Framework and ASP.NET MVC4 application

Introduction

In this post, How to implement Basic CRUD Functionality with the Entity Framework and ASP.NET MVC4 application.
I have split the entire application split into following 3 parts for making things more simple and understandable specially for beginners.

Part 1 : Perform read functionality of CRUD Operation.
Part 2 : Perform create and update functionality of CRUD Operation.
Part 3 : Perform delete functionality of CRUD Operation.

Steps :

Step-1: Write function for fetch countries from database.

Here I have written the below function "GetCountry" into "Contacts" Controller.

            private List<Country> GetCountry()
            {
                using (MyDatabaseEntities dc = new MyDatabaseEntities())
                {
                    return dc.Countries.OrderBy(a => a.CountryName).ToList();
                }
            }

Step-2: Write function for fetch states from database.

Here I have written the below function "GetState" into "Contacts" Controller.

            private List<State> GetState(int countryID)
            {
                using (MyDatabaseEntities dc = new MyDatabaseEntities())
                {
                    return dc.States.Where(a => a.CountryID.Equals(countryID)).OrderBy(a => a.StateName).ToList();
                }
            }

Step-3: Write function for return state list of selected country in json format, which we will use for cascade dropdown.

Here I have written the below function "GetStateList" into "Contacts" Controller.

             public JsonResult GetStateList(int countryID)
            {
                using (MyDatabaseEntities dc = new MyDatabaseEntities())
                {
                
                    return new JsonResult { Data = GetState(countryID), JsonRequestBehavior = JsonRequestBehavior.AllowGet };
                }
            }

Step-4: Write function for fetch contact data from database.

Here I have written the below function "GetContact" into "Contacts" Controller.

            public Contact GetContact(int contactID)
            {
                Contact contact = null;
                using (MyDatabaseEntities dc = new MyDatabaseEntities())
                {
                    var v = (from a in dc.Contacts
                             join b in dc.Countries on a.CountryID equals b.CountryID
                             join c in dc.States on a.StateID equals c.StateID
                             where a.ContactID.Equals(contactID)
                             select new
                             {
                                 a,
                                 b.CountryName,
                                 c.StateName
                             }).FirstOrDefault();
                    if (v != null)
                    {
                        contact = v.a;
                        contact.CountryName = v.CountryName;
                        contact.StateName = v.StateName;
                    }
                    return contact;
                }
            }

Step-5: Add new action into your controller for get view for Save (Add and Edit) contact.

Here I have used "Save" Action. Please write this following code

            public ActionResult Save(int id = 0)
            {
                List<Country> country = GetCountry();
                List<State> states = new List<State>();
                if (id > 0)
                {
                    //Update
                    var c = GetContact(id);
                    if (c != null)
                    {
                        ViewBag.Countries = new SelectList(country, "CountryID", "CountryName", c.CountryID);
                        ViewBag.States = new SelectList(GetState(c.CountryID), "StateID", "StateName", c.StateID);
                    }
                    else
                    {
                        return HttpNotFound();
                    }
                    return View(c);
                }
                else
                {
                    //Create 
                    ViewBag.Countries = new SelectList(country, "CountryID", "CountryName");
                    ViewBag.States = new SelectList(states, "StateID", "StateName");
                    return View();
                }
            }

Step-6: Add view for the Action & design.

Right Click on Action Method (here right click on the action) > Add View... > Enter View Name > Select View Engine (Razor) > Check "Create a strong-typed view" > Select your model class > Add.
[N:B:Please Rebuild solution before add view.]

Step-7: Add following jquery code in the view for cascade dropdown (country > state).

Please write this following code

        <script>
        $(document).ready(function () {
            $('#CountryID').change(function () {
                var countryID = $(this).val();
                var $state = $('#StateID');
                $state.empty();
                $state.append($('<option></option>').val('').html('Please Wait...'));
 
                if (countryID =="") {
                    $state.empty();
                    $state.append($('<option></option>').val('').html('Select State'));
                    return;
                }
 
                $.ajax({
                    url: '/Contacts/GetStateList',
                    type: 'GET',
                    data: { 'countryID': countryID },
                    dataType: 'json',
                    success: function (d) {
                        $state.empty();
                        $state.append($('<option></option>').val('').html('Select State'));
                        $.each(d, function (i, val) {
                            $state.append($('<option></option>').val(val.StateID).html(val.StateName));
                        });
                    },
                    error: function () {
                        alert('Error');
                    }
                });
            });
        });
    </script>

Step-8: Add an another action for POST method for Save contact to the database.

Please write this following code

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Save(Contact c)
        {
            string message = "";
            bool status = false;
 
            //Save 
            if (ModelState.IsValid)
            {
                using (MyDatabaseEntities dc = new MyDatabaseEntities())
                {
                    if (c.ContactID > 0)
                    {
                        //Update
                        var v = dc.Contacts.Where(a => a.ContactID.Equals(c.ContactID)).FirstOrDefault();
                        if (v != null)
                        {
                            v.ContactPerson = c.ContactPerson;
                            v.ContactNo = c.ContactNo;
                            v.CountryID = c.CountryID;
                            v.StateID = c.StateID;
                        }
                        else
                        {
                            return HttpNotFound();
                        }
                    }
                    else
                    {
                        //Add new 
                        dc.Contacts.Add(c);
                    }
                    dc.SaveChanges();
                    status = true;
                    return RedirectToAction("Index");
                }
            }
            else
            {
                message = "Error! Please try again.";
                ViewBag.Countries = new SelectList(GetCountry(), "CountryID", "CountryName", c.CountryID);
                ViewBag.States = new SelectList(GetState(c.CountryID), "StateID", "StateName", c.StateID);
            }
            ViewBag.Message = message;
            ViewBag.Status = status;
            return View(c);
        }

Step-9: Run Application.

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