Model binding is one of the magic things in MVC framework. Model binding is ASP.NET MVC's mechanism for mapping HTTP request data directly into action method parameters and custom. We know that if the model property matches exactly with view, then MVC architecture automatically takes care of the model binding process. This is very simple and straight forward.
But, if the model property is not matched
exactly with the view? Then how do we bind model in time of data submission?
Then we will apply MVC Custom Model
Binding using IModelBinder
and DefaultModelBinder
Create database testdb
use testdb
-- create table Student….
create table Student
(
RollNo int primary key,
Name varchar(50),
Gender varchar(50) constraint
Gender_Constraint check(Gender
in ('Male','Female')),
DOB DateTime
)
Prior to custom binder concept, MVC
architecture used to automatically bind the data fields, when view and model
design matches.
But in this scenario we can see that the values
posted from the form are available in
FormCollection as well as Request.Form to model, view has seven controls
like(rollno,firstname,lastname,gender,day,month,year) and model
has four data fields like(RollNo,Name,Gender,Dob).
So we have to use custom model binder to manually bind the data fields.
First we will take MvcApplication and take
class which name is StudentBinder.cs in Model Folder
namespace
WebApplication2.Models
{
public class StudentBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
var request =
controllerContext.HttpContext.Request;
int _rollno = Convert.ToInt32(request.Form.Get("RollNo"));
string _fname =
request.Form.Get("FirstName");
string _lname =
request.Form.Get("LastName");
string _gender =
request.Form.Get("Gender");
int _day = Convert.ToInt32(request.Form.Get("Days"));
int _month =Convert.ToInt32(
request.Form.Get("Months"));
int _year = Convert.ToInt32(request.Form.Get("Years"));
return new Student { RollNo = _rollno,
Name = _fname+" "+_lname,
Gender = _gender, DOB = new DateTime(_year,_month,_day)
};
}
}
}
Then we can add Controller which
name is MyCollegeController.cs
using System;
using
System.Collections.Generic;
using System.Linq;
using System.Web;
// using this namesapce
using System.Web.Mvc;
using
WebApplication2.Models;
namespace
WebApplication2.Controllers
{
public class MyCollegeController : Controller
{
// GET: MyCollege
// database ....
testdbEntities database = new testdbEntities();
List<SelectListItem> days = new List<SelectListItem>();
List<SelectListItem> years = new List<SelectListItem>();
List<SelectListItem> months = new List<SelectListItem>();
string[] mon = new string[12] { "Jan", "Feb", "March", "Apr", "May", "June", "July", "Aug", "Sep", "Oct", "Nov", "Dec" };
//
this method for how to bind day,month
year on View……
public void DayMonthYear()
{
// this code for month ………………
for (int i = 0; i <
mon.Length; i++)
{
months.Add(new SelectListItem()
{
Value = (i + 1).ToString(),
Text = mon[i]
});
}
ViewBag.Months = months;
// this code for days ………………
for (int i = 0; i <= 31;
i++)
{
days.Add(new SelectListItem()
{
Value = i.ToString(),
Text = i.ToString()
});
}
ViewBag.Days = days;
// this code for years ………………
for (int i = 1975; i <= DateTime.Now.Year; i++)
{
years.Add(new SelectListItem()
{
Value = i.ToString(),
Text = i.ToString()
});
}
ViewBag.Years = years;
}
[HttpGet]
public ActionResult Index()
{
DayMonthYear();
return View();
}
[HttpPost]
public ActionResult Index([ModelBinder(typeof(StudentBinder))] Student entity )
{
try {
Student ss = new Student
{
RollNo = entity.RollNo,
Name = entity.Name,
Gender = entity.Gender,
DOB = entity.DOB
};
database.Students.Add(ss);
database.SaveChanges();
TempData["msg"] = "saved successfully";
DayMonthYear();
}
catch (Exception ex)
{
TempData["msg"] = ex.Message;
}
return View();
}
}
}
This code for
Index.cshtml…………………………………..
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Index</title>
</head>
<body>
<div>
@using (Html.BeginForm())
{
<table width="50%" border="1">
<tr><td>RollNo</td><td>@Html.TextBox("RollNo")</td></tr>
<tr><td>First Name</td><td>@Html.TextBox("FirstName")</td></tr>
<tr><td>Last Name</td><td>@Html.TextBox("LastName")</td></tr>
<tr>
<td>Gender</td>
<td>
Male:@Html.RadioButton("Gender", "Male")
Female: @Html.RadioButton("Gender", "Female")
</td>
</tr>
<tr>
<td>Date Of Birth</td>
<td>
@Html.DropDownList("Days", "Day")
@Html.DropDownList("Months", "month")
@Html.DropDownList("Years", "year")
</td>
</tr>
<tr><td colspan="2"><input type="submit" value="Save" />@TempData["msg"]</td></tr>
</table>
}
</div>
</body>
</html>
If you want to use Custom Model
Binding in your MvcApplication then you have to make
some changes in Global.asax
in your Application and
the code we
have changed is being
highlighted below by
yellow color
using System;
using
System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using
System.Web.Optimization;
using System.Web.Routing;
using
WebApplication2.Models;
namespace WebApplication2
{
public class MvcApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
ModelBinders.Binders.Add(typeof(Student), new StudentBinder());
}
}
}
Result
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