How to: Add and Modify Objects with Table-per-Type Inheritance (Entity Framework)

This topic uses the Entity Data Model (EDM) defined in the topic How to: Define a Model with Table-per-Type Inheritance (Entity Framework). It demonstrates how to add an instance of the derived type in a Table-per-Type inheritance hierarchy.

To create a project using Table-Per-Type inheritance

1. Create a console application project named SchoolDataClient and add references to System.Data.Entity and System.Runtime.Serialization.

2. Add a reference to the dll built from the inheritance hierarchy described in How to: Define a Model with Table-per-Type Inheritance (Entity Framework).

3. Add the schemas from the topic How to: Define a Model with Table-per-Type Inheritance (Entity Framework) to the same folder as the SchoolDataClient executable.

4. Add an application configuration file to the project with the following content.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <connectionStrings><add name="SchoolDataLibContainer" 
   connectionString=
   "metadata=res://*/SchoolDataLib.csdl|
   res://*/SchoolDataLib.ssdl|
   res://*/SchoolDataLib.msl;provider=System.Data.SqlClient;
   provider connection string=&quot;
   Data Source=localhost;
   Initial Catalog=SchoolData;Integrated Security=True;
   MultipleActiveResultSets=True&quot;" 
   providerName="System.Data.EntityClient" />
  </connectionStrings>
</configuration>

To add an instance of the derived type

1. Create an instance of the DeptEngineering type named newDept.

2. Initialize the data of properties of newDept.

3. Create a new instance of the Person type.

4. Assign the PersonCategory property to 3 to indicate the Administrator category.

5. Initialize the properties of newAdmin.

6. Assign the new Person to the Administrator property of newDept.

7. Add newDept and newAdmin to storage and save changes.

Example

Option Explicit On
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Xml
Imports System.Xml.Linq
Imports System.Text
Imports SchoolDataLib

Module Module1

    Sub Main()
        Try
            Using objectContext As SchoolDataLibContainer = 
                                       New SchoolDataLibContainer ()
                ' Display departments and administrators.
                For Each dept As Department In objectContext.Departments
                    Console.WriteLine("School: {0} Budget: {1}", _
                            dept.Name, dept.Budget)

                    ' Load associated contact reference if any.
                    dept.AdministratorReference.Load()
                    If dept.Administrator IsNot Nothing Then
                        Console.WriteLine("Administrator: {0} {1}", _
                            dept.Administrator.FirstName, _
                            dept.Administrator.LastName)
                    End If
                Next

                For Each eDept As DeptEngineering In _
                        objectContext.Departments.OfType(Of DeptEngineering)()
                    Console.WriteLine("{0} LabBudget: {1} FiberOp Budget: {2}", _
                        eDept.Name, eDept.LabBudget.ToString(), _
                        eDept.FiberOpticsBudget.ToString())
                Next

                Dim countDept As Integer = 0
                Dim newDept As DeptEngineering = New DeptEngineering()

                For Each dept As Department In objectContext.Departments
                    countDept = countDept + 1
                Next

                newDept.DepartmentID = countDept + 1
                newDept.Name = "Engineering School " + (countDept + 1).ToString()
                newDept.StartDate = DateTime.Now
                newDept.FiberOpticsBudget = 250000.0
                newDept.LabBudget = 400000.0
                newDept.Budget = newDept.FiberOpticsBudget + newDept.LabBudget

                ' Create new contact item to be 
                ' added as school administrator.
                Dim countPerson As Integer = 0
                For Each pers As Person In objectContext.People
                    countPerson = countPerson + 1
                Next

                Dim newAdmin As Administrator = New Administrator()
                newAdmin.PersonID = countPerson + 1
                newAdmin.FirstName = "Tony"
                newAdmin.LastName = "Allen"
                newAdmin.AdminDate = DateTime.Now - New TimeSpan(2000, 0, 0, 0)

                ' Assign the contact to Administrator property.
                newDept.Administrator = newAdmin

                ' Add admin and school to object context.
                objectContext.AddToPeople("People", newAdmin)
                objectContext.AddToDepartments("Departments", newDept)

                objectContext.SaveChanges()
            End Using

        Catch ex As System.Data.MappingException
            Console.WriteLine(ex.ToString())
        Catch ex As System.Data.CommandExecutionException
            Console.WriteLine(ex.ToString())
        Catch ex As System.Data.UpdateException
            Console.WriteLine(ex.ToString())
        End Try

    End Sub

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SchoolDataLib;

namespace SchoolDataClient
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                using (SchoolDataLibContainer objectContext =
                                      new SchoolDataLibContainer())
                {
                    DeptEngineering newDept =
                                         new DeptEngineering();

                    int countDept = 
                        objectContext.Departments.Count<Department>();
                    newDept.DepartmentID = countDept + 1;
                    newDept.Name = "Engineering School " +
                                          (countDept + 1).ToString();
                    newDept.StartDate = DateTime.Now;
                    newDept.FiberOpticsBudget = 250000.00M;
                    newDept.LabBudget = 400000.00M;
                    newDept.Budget = newDept.FiberOpticsBudget + 
                        newDept.LabBudget;

                    // Create new contact item to be 
                    // added as school administrator.
                    int countPerson = objectContext.People.Count<Person>();
                    Administrator newAdmin = new Administrator();
                    newAdmin.PersonID = countPerson + 1;
                    newAdmin.FirstName = "Jesper";
                    newAdmin.LastName = "Aaberg";
                    newAdmin.AdminDate = DateTime.Now - 
                                     new TimeSpan(2000, 0, 0, 0);

                    // Assign the contact to Administrator property.
                    newDept.Administrator = newAdmin;

                    // Add admin and school to object context.
                    objectContext.AddToPeople(newAdmin);
                    objectContext.AddToDepartments(newDept);

                    objectContext.SaveChanges();
                }
            }

            catch (System.Data.MappingException e)
            {
                Console.WriteLine(e.ToString());
            }
            
            catch (System.Data.UpdateException e)
            {
                Console.WriteLine(e.ToString());
            }
        }
    }
}

See Also

Tasks

How to: Define a Model with Table-per-Type Inheritance (Entity Framework)
How to: Create and Execute Object Queries using Table-per-Type Inheritance (Entity Framework)