Working with Multiple Tables in ASP.NET MVC using Entity Framework

Back to: ASP.NET MVC Tutorial

Working with Multiple Tables in ASP.NET MVC using Entity Framework

In this article, I am going to discuss Working with Multiple tables in ASP.NET MVC applications using Entity Framework. Please read our previous article where we discussed Action Link HTML Helper in ASP.NET MVC application.  At the end of this article, you will understand how to work with multiple tables in ASP.NET MVC Application using Entity Framework.

Database tables used in this demo:

We are going to work with the below two tables i.e. Department and Employee.

Please use the below SQL script to create and populate Department and Employee tables with the required test data.

-- Create Department Table
Create table Department
(
  Id int primary key identity,
  Name nvarchar(50)
)
GO

-- Insert some test data into Department table
Insert into Department values('IT')
Insert into Department values('HR')
Insert into Department values('Marketing')
GO
<br>-- First Drop the Existing Employee table<br>DROP Table Employee;<br>
-- Create Employee Table
Create table Employee
(
  EmployeeId int Primary Key Identity(1,1),
  Name nvarchar(50),
  Gender nvarchar(10),
  City nvarchar(50),
  DepartmentId int
)
GO


-- Add Foreign Key into Employee Table Reference to the Department Table
Alter table Employee
add foreign key (DepartmentId)
references Department(Id)
GO

-- Insert Some Test data into Employee Table
Insert into Employee values('Pranaya','Male','Mumbai',1)
Insert into Employee values('Anurag','Male','Hyderabad',3)
Insert into Employee values('Priyanka','Female','Bangalore',3)
Insert into Employee values('Subrat','Male','Hyderabad',2)
Insert into Employee values('Sudhanshu','Male','Mumbai',1)
Insert into Employee values('Preety','Female','Bangalore',2)
Insert into Employee values('Sandeep','Male','Hyderabad',1)
Insert into Employee values('Sambit','Male','Bangalore',2)
Insert into Employee values('Hina','Female','Mumbai',1)
GO

Example to understand working with multiple tables in MVC Application:

Following is our business requirement.

1. We need to display all the departments from the Department table. The Department names should be rendered as hyperlinks. This is going to be our department list page.
2. On clicking the department name link, all the employees in that particular department should be displayed. The employee names also here going to be rendered as hyperlinks. This is going to be our employee list page.
3. When the user clicks on the employee name link the full details of that employee should be displayed in the browser. This is going to be our employee details page.
4. A link should also be provided on the employee full details page to navigate back to the Employee List page. Along the same lines, a link should also be provided on the employee list page to navigate back to the Departments’s list page.

The following image gives you the overall workflow of our requirement 

Note: We are going to work with the same example that we started in our previous two articles. So please read the below two articles before proceeding to this article.

Entity Framework in ASP.NET MVC

Generating hyperlinks using Action Link HTML helper

To implement the above example first we need to update the EmployeeDataModel.edmx file.

Update the EDMX file

Double click on the EmployeeDataModel.edmx file which is in the Models folder. Once you click on the edmx file the following screen will open.

Right-click anywhere in the edmx file and then click on the “update model from the database” option as shown in the below image.

Then choose the add button and then select the Department table as shown in the below image.

Next, choose the Refresh button and select the Employee table and click on the Finish button as shown in the below image.

Once you click on the Finish button, you will get an error saying Salary Property is not mapped. Simply select the Salary Property from the Employee Model of the edmx file, right-click on it, and then click on delete from the model as shown in the below image.

That’s it. Save the edmx file and build the solution. Let’s have a look of the files that are generated and modified by Entity Framework.

Department.cs (This file is added by Entity Framework)

namespace CRUD_OperationsInMVC.Models
{
    using System;
    using System.Collections.Generic;
    
    public partial class Department
    {
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
        public Department()
        {
            this.Employees = new HashSet<Employee>();
        }
    
        public int Id { get; set; }
        public string Name { get; set; }
    
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
        public virtual ICollection<Employee> Employees { get; set; }
    }
}

Employee.cs (This file is modified by Entity Framework)

namespace CRUD_OperationsInMVC.Models
{
    using System;
    using System.Collections.Generic;
    
    public partial class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Gender { get; set; }
        public string City { get; set; }
        public Nullable<int> DepartmentId { get; set; }
    
        public virtual Department Department { get; set; }
    }
}

EmployeeDataModel.Context.cs (This file is modified by Entity framework)

namespace CRUD_OperationsInMVC.Models
{
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Infrastructure;
    
    public partial class EmployeeDBContext : DbContext
    {
        public EmployeeDBContext()
            : base("name=EmployeeDBContext")
        {
        }
    
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }
    
        public virtual DbSet<Employee> Employees { get; set; }
        public virtual DbSet<Department> Departments { get; set; }
    }
}

These are the changes done by entity framework.

Add Department Controller

Right click on the “Controllers” folder and add a MVC5 Empty Controller with the name DepartmentController and then Copy and paste the following code into it.

namespace CRUD_OperationsInMVC.Controllers
{
    public class DepartmentController : Controller
    {
        public ActionResult Index()
        {
            EmployeeDBContext dbContext = new EmployeeDBContext();
            List<Department> listDepartments = dbContext.Departments.ToList();
            return View(listDepartments);
        }
    }
}

@using CRUD_OperationsInMVC.Models;
@model IEnumerable<Department>
<div style="font-family:Arial">
    @{
        ViewBag.Title = "Departments List";
    }

    <h2>Departments List</h2>
    <ul>
        @foreach (Department department in @Model)
        {
            <li>@Html.ActionLink(department.Name, "Index", "Employee", new { departmentId = department.Id }, null)</li>
        }
    </ul>
</div>

namespace CRUD_OperationsInMVC.Controllers
{
    public class EmployeeController : Controller
    {
        public ActionResult Index(int departmentId)
        {
            EmployeeDBContext dbContext = new EmployeeDBContext();
            List<Employee> employees = dbContext.Employees.Where(emp => emp.DepartmentId == departmentId).ToList();
            return View(employees);
        }
        public ActionResult Details(int id)
        {
            EmployeeDBContext dbContext = new EmployeeDBContext();
            Employee employee = dbContext.Employees.FirstOrDefault(x => x.EmployeeId == id);
            return View(employee);
        }
    }
}

@model IEnumerable<CRUD_OperationsInMVC.Models.Employee>
@using CRUD_OperationsInMVC.Models;
<div style="font-family:Arial">
    @{
        ViewBag.Title = "Employee List";
    }
    <h2>Employee List</h2>
    <ul>
        @foreach (Employee employee in @Model)
        {
            <li>@Html.ActionLink(employee.Name, "Details", new { id = employee.EmployeeId })</li>
        }
    </ul>
    @Html.ActionLink("Back to Department List", "Index", "Department")
</div>

@model CRUD_OperationsInMVC.Models.Employee
@{

    ViewBag.Title = "Employee Details";
}
<h2>Employee Details</h2>
<table style="font-family:Arial">
    <tr>
        <td>Employee ID:</td>
        <td>@Model.EmployeeId </td>
    </tr>
    <tr>
        <td>Name:</td>
        <td>@Model.Name</td>
    </tr>
    <tr>
        <td>Gender:</td>
        <td>@Model.Gender</td>
    </tr>
    <tr>
        <td>City:</td>
        <td>@Model.City</td>
    </tr>
</table>

<p>
   @Html.ActionLink("Back to Employee List", "Index", new { departmentId = @Model.DepartmentId })  
</p>

namespace CRUD_OperationsInMVC
{
    public class RouteConfig
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Department", action = "Index", id = UrlParameter.Optional }
            );
        }
    }
}