Part 18 - Updating data in mvc

Suggested Videos 
Part 15 - Updatemodel function in MVC
Part 16 - Difference between UpdateModel and TryUpdateModel
Part 17 - Editing a model in mvc



In this video we will discuss updating data in mvc. Please watch Part 17, before proceeding.


Step 1: Create a stored procedure to update employee data.
Create procedure spSaveEmployee      
@Id int,
@Name nvarchar(50),      
@Gender nvarchar (10),      
@City nvarchar (50),      
@DateOfBirth DateTime 
as      
Begin      
 Update tblEmployee Set
Name = @Name,
Gender = @Gender,
City = @City,
DateOfBirth = @DateOfBirth
 Where Id = @Id
End



Step 2: Add the following "SaveEmployee()" method to "EmployeeBusinessLayer" class in "BusinessLayer" project. This method is used to save employee data to the database table.
public void SaveEmmployee(Employee employee)
{
    string connectionString =
            ConfigurationManager.ConnectionStrings["DBCS"].ConnectionString;

    using (SqlConnection con = new SqlConnection(connectionString))
    {
        SqlCommand cmd = new SqlCommand("spSaveEmployee", con);
        cmd.CommandType = CommandType.StoredProcedure;

        SqlParameter paramId = new SqlParameter();
        paramId.ParameterName = "@Id";
        paramId.Value = employee.ID;
        cmd.Parameters.Add(paramId);

        SqlParameter paramName = new SqlParameter();
        paramName.ParameterName = "@Name";
        paramName.Value = employee.Name;
        cmd.Parameters.Add(paramName);

        SqlParameter paramGender = new SqlParameter();
        paramGender.ParameterName = "@Gender";
        paramGender.Value = employee.Gender;
        cmd.Parameters.Add(paramGender);

        SqlParameter paramCity = new SqlParameter();
        paramCity.ParameterName = "@City";
        paramCity.Value = employee.City;
        cmd.Parameters.Add(paramCity);

        SqlParameter paramDateOfBirth = new SqlParameter();
        paramDateOfBirth.ParameterName = "@DateOfBirth";
        paramDateOfBirth.Value = employee.DateOfBirth;
        cmd.Parameters.Add(paramDateOfBirth);

        con.Open();
        cmd.ExecuteNonQuery();
    }
}

Step 3: Copy and paste the following "Edit" controller action method in "EmployeeController.cs" file. 
[HttpPost]
public ActionResult Edit(Employee employee)
{
    if (ModelState.IsValid)
    {
        EmployeeBusinessLayer employeeBusinessLayer =
            new EmployeeBusinessLayer();
        employeeBusinessLayer.SaveEmmployee(employee);

        return RedirectToAction("Index");
    }
    return View(employee);
}

Please note:
1. This method is decorated with [HttpPost] attribute. So this method only responds to HTTP post request when updating data.
2. The "Edit" action method receives the modified "Employee" object. This object is then passed to SaveEmployee() method, which saves the employee details. After the employee details are saved, the user is redirected to "Index" action.
3. If there are model validation errors, none of the code in the IF block gets executed. In this case, the user stays on the "Edit" view. Since we are passing "Employee" object to the "Edit" view, the user gets to see the validation errors. This allows him to fix those errors and re-submit the view.