Gil Fink's Blog : Entity Framework

VSLive Chicago Sessions Slide Decks and Demos

Gil Fink — Wed, 15 May 2013 23:13:15 GMT

VSLive Chicago Sessions Slide Decks and Demos

Just finished delivering three sessions in VSLive Chicago. It was nice meeting all the attendees and talking about technologies that I like like HTML5, OData and Entity Framework. Here is a list of the sessions that I delivered:

You can find the slide decks and demos in this link.

New Speaking Engagement – VSLive Chicago

Gil Fink — Thu, 24 Jan 2013 06:47:39 GMT

New Speaking Engagement – VSLive Chicago

Lately, I have been chosen to speak at VSLive Chicago conference. The conference will take place in May 13-16 at Hilton Chicago, USA. This is going to be the second time that I’m speaking in VSLive conferences and I’m very excited. In the conference I’ll have three sessions:

Working with Client-Side HTML5 Storage Technologies
HTML is the markup language that every web developer uses in order to structure and present content in the Internet. HTML5 is the standard that is being shaped and developed currently. It extends and improves the last HTML4 standard and takes it to the next level with support for multimedia, communication, semantics and more. In this session we will deep dive into the new storage options that HTML5 brings and how to use them. The session will discuss Web Storage, IndexedDB and AppCache APIs.
OData - Oh Yeah
Open Data Protocol (OData) is a protocol for exposing and consuming data on the web. The OData ecosystem is a growing community of data producers and consumers using the Open Data Protocol to exchange data. This session will explain what the Open Data Protocol (OData) is and how to create OData feeds using WCF Data Services.
Not Just a Designer: Code First and Entity Framework
Entity Framework 4 brought many new opportunities for building complex data driven applications. Code First is an Entity Framework capability that provides a code-centric experience for interacting with models and databases. This session will cover several Entity Framework features such as Code First, DbContext API and Migrations.

See you there!

Wrapping up the VSLive Redmond Week

Gil Fink — Sat, 11 Aug 2012 21:49:47 GMT

Wrapping up the VSLive Redmond Week

A few days ago I had the opportunity to deliver two sessions in the VSLive Redmond conference. In the conference I delivered two different sessions:

Working with Client-Side HTML5 Storages – slide deck and demos are available to download from this link.
Not Just a Designer: Code First in Entity Framework – slide deck and demos are available to download from this link.

I want to thank all of the attendees in both of the sessions. I had the opportunity to meet people who crave for new technologies like me so it was a cool experience.

Apart from the two sessions, I had a week full of meetings in Microsoft and probably in the near future I’ll be able to tell more about that. I also had the opportunity to speak in the vNEXT Seattle Developers Community. I had a 45 minutes session about “Using Communication and Messaging API in The HTML5 World”. Even though 45 minutes aren’t enough for the topic, I hope that the attendees had the opportunity to see things that they can expect to use in the near future.

All in all I had good times during the week.

Not Just a Designer: Code First in Entity Framework – VSLive Session Slide Deck and Demos

Gil Fink — Fri, 10 Aug 2012 08:45:10 GMT

Not Just a Designer: Code First in Entity Framework – VSLive Session Slide Deck and Demos

Today I had the pleasure of delivering another session in VSLive conference. The session that I delivered was about Code First in Entity Framework and I covered Code First, DbContext API and Entity Framework Migrations.

I want to thank all the attendees who came to my session and also to VSLive organizers for giving me the opportunity to speak in the conference. You can download the slide deck and demos from this link.

New Speaking Engagement – Visual Studio Live

Gil Fink — Thu, 12 Apr 2012 20:19:26 GMT

New Speaking Engagement – Visual Studio Live

Lately, I have been chosen to speak at the Visual Studio Live (VSLive) conference. The conference will take place in August 6-10 at Microsoft headquarters in Redmond, WA, USA. I’m going to have a ~16 hours flight to go there, but I’m not flying alone. Ido Flatow, one of my Sela Group colleagues which is a “veteran” VSLive speaker, is going to the conference also and will have two sessions (one about ASP.NET Web APIs and the other about Windows Azure).

I’ll have two sessions:

Working with Client-Side HTML5 Storages
HTML is the markup language that every web developer uses in order to structure and present content in the Internet. HTML5 is the standard that is being shaped and developed currently. It extends and improves the last HTML4 standard and takes it to the next level with support for multimedia, communication, semantics and more. In this session we will discuss the new storage options that HTML5 brings and how to use them.
Not Just a Designer: Code First and Entity Framework
Entity Framework 4 brought many new opportunities for building complex data driven applications. Code First is a new Entity Framework capability that provides a code-centric experience for interacting with models and databases. This session will cover several Entity Framework features such as Code First, and provide an overview for what to expect from Entity Framework vNext.

See you there!

Avoiding Circular Reference for Entity in JSON Serialization

Gil Fink — Mon, 17 Oct 2011 15:10:09 GMT

Avoiding Circular Reference for Entity in JSON Serialization

One problem that I was facing yesterday while working on an ASP.NET MVC application was a JSON serialization issue. The problem was a circular reference caused by the DataContractJsonSerializer because of relations between the entity and other entities. In this post I’ll show you how you can use a simple workaround in order to avoid the problem.

The JSON Serialization Error

Returning the output of the JSON method in an ASP.NET MVC controller with a JSON object graph based on an Entity Framework Code First object causes the following error – “A circular reference was detected while serializing an object of type ‘object name’”. Here is an example of a method that might cause the problem:

     public ActionResult Details(int id)

        using (var context = new DbEntities())

        {             

            var entity = context.Entities.

              Include(e => e.OtherEntities).

              FirstOrDefault(e => e.EntityId == id);

            return Json(entity, JsonRequestBehavior.AllowGet);

        }

    }

Pay attention that this is a fake method and isn’t a real method.

The error I was getting didn’t show up on the server side (nothing crashed). I found the error by inspecting Fiddler since the application kept on working but the client side callback wasn’t. Here is an example of the calling client side function which is using jQuery getJSON function:

    function getDetails() {

        $.getJSON('/ApplicationName/Details/' + Id, {}, function (data) {

            fillDetails(data);

        });

    }

The circular reference is a known problem that my colleague Ido wrote about in Microsoft Connect.
So how to avoid it?

The Workaround

Use a data projection to project only the relevant data that you need and send this data to the client side. This workaround will minimize the object that you are sending and also play a role as a ViewModel kind of object instead of an entity when it is available on the client side. Here is an example of using the workaround with the previous method:

    public ActionResult Details(int id)

    {

      using (var context = new DbEntities())

      {

        var entity = context.Entities.

          Include(g => g.OtherEntities).

          Select(e => new { 

            e.Id,

            e.Url,

            e.Name,

            e.OtherEntities

          }).

          FirstOrDefault(e => e.Id == id);

        return Json(entity, JsonRequestBehavior.AllowGet);

      }

    }

Summary

The circular reference issue might happen also in WCF script services or in other places while serializing Entity Framework’s entities into JSON representation. The simple workaround is to create a projection of the data that you need and serialize it into JSON representation. One of the gains of this method is minimizing the response size from the server.

Creating a Many To Many Mapping Using Code First

Gil Fink — Mon, 01 Aug 2011 14:17:19 GMT

Creating a Many To Many Mapping Using Code First

Today I got a question about how to create a many to many mapping using Entity Framework Code First. The question was how to create the mapping with an existing database. Here is an explanation how to achieve that.

Creating Many To Many Mapping

Sometimes there is a need to create a many to many relation in the database. When we want to achieve that we will create a relation table which will hold the primary key from every table in the many to many relation. Here is an example of a simple many to many relation that can exist in a database:

In Code First, when we want to create such a relation all we have to do is to create the relevant entities which will hold an ICollection in each side of the relation and create the relevant DbContext. Here is an example for a many to many relation in Code First:

       public class Person

      {

        public int PersonId { get; set; }

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public ICollection<Course> CoursesAttending { get; set; }

        public Person()

        {

          CoursesAttending = new HashSet<Course>();

        }

      }

      public class Course

      {

        public int CourseId { get; set; }

        public string Title { get; set; }

        public ICollection<Person> Students { get; set; }

        public Course()

        {

          Students = new HashSet<Person>();

        }

      }

      public class SchoolContext : DbContext

      {

        public DbSet<Course> Courses { get; set; }

        public DbSet<Person> People { get; set; }

        public SchoolContext()

          : base("MyDb")

        {

        }

      }

Simple as that. The problem starts when we have an existing database where the column names or the relation name aren’t generated by Code First convention engine. In the previous figure of the database, Code First will generate the column names – Person_PersonId and Course_CourseId which don’t match to the existing table.

Using Code First Fluent API to Create a Many To Many Relation Mapping

So we have a small problem with existing relation tables. We can solve the problem by overriding the OnModelCreating method and adding the mapping using Code First fluent API. Here is an example of such a mapping to solve the previous model’s problem:

      public class SchoolContext : DbContext

      {

        public DbSet<Course> Courses { get; set; }

        public DbSet<Person> People { get; set; }

        public SchoolContext()

          : base("MyDb")

        {

        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)

        {

          modelBuilder.Entity<Course>().

            HasMany(c => c.Students).

            WithMany(p => p.CoursesAttending).

            Map(

             m =>

             {

               m.MapLeftKey("CourseId");

               m.MapRightKey("PersonId");

               m.ToTable("PersonCourses");

             });

        }

      }

In the OnModelCreating you will use the HasMany to indicate that course has many students and WithMany to indicate that a person can attend a lot of courses. The Map method will tell Code First how to build the relation table with the relevant name (using ToTable mapping) and with the relevant keys (MapLeftKey and MapRightKey).

Summary

Creating a many to many relation with Code First is easy. You need to get used to the fluent API if you have an existing database but the API is self explanatory so it makes your job easier.

Microsoft Entity Framework June 2011 CTP was Released

Gil Fink — Fri, 01 Jul 2011 15:34:00 GMT

Microsoft Entity Framework June 2011 CTP was Released

Yesterday, ADO.NET team released a new EF CTP. If you attended my Sela Dev. Days EF4.1 tutorial day this week you heard about this release and the new features. Here is the list of new features to expect from EF4.2 that you can evaluate with the new EF CTP:

Runtime Features

The Enum data-type. At last we will have support for enums. You can use either the Entity Designer within Visual Studio to model entities that have Enum properties, or use the Code First workflow to define entities that have Enum objects as properties. You can use your Enum property just like any other scalar property, such as in LINQ queries and updates.
Geography and Geometry Spatial data-types which are natively supported by the Entity Framework.
Table-valued functions can be added to entity data models. A table-valued function is similar to a stored procedure, but the result of executing the table-valued function is composable, meaning you can use it as part of a LINQ query.
Stored procedures can now have multiple result sets in your entity data model.
The Entity Framework June 2011 CTP includes several SQL generation improvements.
LINQ queries are now automatically compiled and cached to improve query performance.

Entity Framework Designer Features

The Entity Designer now supports the creation of enums, spatial data-types and table-value functions from the designer surface.
You can now create multiple diagrams for each entity data model. Each diagram can contain entities and relationships to make visualizing your model easier.
The StoreGeneratedPattern for key columns can now be set on an entity Properties window and this value will propagate from your entity model down to the store definition.
Diagram information is now stored in a separate file from the edmx or entity code files.
Batch import for stored procedures as function imports. The result shape of each stored procedure will automatically become a new complex type in your entity model. This makes getting started with stored procedures very easy.
The Entity Designer surface now supports selection driven highlighting and entity shape coloring.

Mode Information About the CTP Release

For further information about the CTP you can go to this link. Pay attention for the Getting the Microsoft Entity Framework June 2011 CTP and the Getting Started sections in the announcement and also to the Uninstalling section.

Here are some CTP walkthroughs that were published in ADO.NET team blog:

Enjoy!

My Sela Dev-Days Experience

Gil Fink — Wed, 29 Jun 2011 01:21:02 GMT

My Sela Dev-Days Experience

Today I finished my Sela Dev. Days experience. Sela Dev. Days is a conference which include 5 days, 15 top experts, 25 session, and a whole lot of attendees (around 600 people registered for this week). If you are not familiar with Sela Dev. Days you can go to the conference’s site. In the conference I had three tutorial days in three different subjects:

ASP.NET MVC 3, EF Code First integration, and Razor: Oh My!
In this one day tutorial I co-operated with Sebastian Pederiva, a senior consultant in Sela. In the day we gave a crash dived into Microsoft Web Platform – including ASP.NET MVC 3, EF, Web Platform Installer, Razor view engine and more. At the beginning session I introduced Microsoft web platform and ASP.NET MVC. Then, I talked about building models and data access layers for MVC applications on top of Entity Framework and in particular with Code First. In the third session I talked about how to work with controllers and about the routing concept in ASP.NET. Sebastian talked about Razor and how to integrate AJAX into MVC applications using the jQuery library.
HTML 5
In this one day tutorial I talked about what to expect out of the coming HTML5 standards, the new HTML5 elements, how to migrate HTML4 applications to HTML5 (here I gave a case scenario and with the help of the attendees we migrated a blog web page to HTML5) and about some of the new HTML5 API such as Geolocation, Web Workers, Web Sockets, Canvas and more.
Entity Framework 4.1 and Code First
In this one day tutorial I co-operated with Ido Flatow, another senior architect in Sela. I delivered four sessions – introduction to ORMs and EF, querying and manipulating data using Entity Framework, Entity Framework internals and Code First. Ido gave a session about Entity Framework in distributed applications.

I want to thank all the attendees that joined me in the days I delivered.
All the demos can be downloaded from here.

How to Configure a Self Referencing Entity in Code First

Gil Fink — Fri, 03 Jun 2011 18:36:00 GMT

How to Configure a Self Referencing Entity in Code First

A few days ago a worker in Sela asked me how to configure a self referencing entity with EF Code First. In this post I’ll show you how to implement that configuration.

Self Reference Scenarios

There are a lot of scenarios that we will want to implement a self reference between an entity to itself. For example, we do that when we want to create hierarchies in our application - an employee entity that has a self reference to his/her manager is a very common scenario for that. When we want to create that behavior in a database all we have to do is to add a foreign key in the table that point to the table primary key and we are done. But how can we do that in EF Code First?

Configure a Self Reference in Code First

In EF Code First we can use the fluent API in order to configure a self reference. Lets jump into an example that will direct you how to make that configuration.
The first thing is the entity:

public class Employee{  #region Properties   public int EmployeeID { get; set; }  public string FirstName { get; set; }  public string LastName { get; set; }   public int? ManagerID { get; set; }  public Employee Manager { get; set; }   #endregion}

As you might notice there is nothing interesting in the entity itself – just a bunch of properties and the reference to the manager which is another employee.
After we have the entity lets create the context:

public class CompanyContext : DbContext{  #region Properties   public DbSet<Employee> Employees { get; set; }   #endregion   #region Ctor   public CompanyContext()    : base("Company")  {  }   #endregion   #region Methods   protected override void OnModelCreating(DbModelBuilder modelBuilder)  {    modelBuilder.Entity<Employee>().      HasOptional(e => e.Manager).      WithMany().      HasForeignKey(m => m.ManagerID);  }   #endregion}

In the context you need to implement the OnModelCreating method in order to configure the self reference. We start the configuration with the HasOptional method that indicate that the employee might have a manager (or else he/she is the CEO). Then, for the manager we configure a many side with the WithMany method. In the end we use the HasForeignKey method to indicate what is the foreign key (which is the ManagerID in the example). That is it.
In order to finish the example I’ve created a database initializer that inserts some data:

public class ExampleInitializer : DropCreateDatabaseIfModelChanges<CompanyContext>{  #region Methods   protected override void Seed(CompanyContext context)  {    var manager = new Employee    {      FirstName = "emp1",      LastName = "emp1",    };    var emp1 = new Employee    {      FirstName = "emp1",      LastName = "emp1",      Manager = manager    };    var emp2 = new Employee    {      FirstName = "emp2",      LastName = "emp2",      Manager = manager    };     context.Employees.Add(emp1);    context.Employees.Add(emp2);    context.SaveChanges();  }   #endregion}

and a console application that run the example:

class Program{  static void Main(string[] args)  {    Database.SetInitializer(new ExampleInitializer());     using (var context = new CompanyContext())    {      var query = context.Employees.Include(e => e.Manager).ToList();      foreach (var employee in query)      {        Console.WriteLine("{0} {1}", employee.EmployeeID, employee.ManagerID);      }    }  }}

Here is a figure of the output:

Summary

Lets sum up, the post includes a running example of how to configure a self reference entity with Code First. I hope it will help you if you get stuck with such a configuration.

Creating a Code First Database Initializer Strategy

Gil Fink — Mon, 30 May 2011 14:56:44 GMT

Creating a Code First Database Initializer Strategy

Yesterday I helped a colleague with his ASP.NET MVC 3 site deployment. That colleague implemented the data access layer using EF4.1 Code First. One of the restrictions that he had was that he didn’t have database permissions to create a new database and couldn’t use SQL Express or SQL CE in his application. Instead he had an empty database for his disposal in the hosting environment without a way to run SQL scripts… In such a situation the provided Code First database initializer strategies weren’t sufficient (he couldn’t drop or create the database and couldn’t run scripts). In the post I’ll show an example of how to create your own database initializer and show the strategy that helped my colleague to make his deployment.

The Database Initializer Interface

The first thing you have to get familiar with when you want to create your own database initializer is the IDatabaseInitializer generic interface. The IDatabaseInitializer interface is available in the EF4.1 EntityFramework dll in the System.Data.Entity namespace. It exposes only one method - InitializeDatabase:

       namespace System.Data.Entity

      {

        public interface IDatabaseInitializer<in TContext> where TContext : global::System.Data.Entity.DbContext

        {

          // Summary:

          //     Executes the strategy to initialize the database for the given context.

          // Parameters:

          //   context: The context.

          void InitializeDatabase(TContext context);

        }

      }

Creating Database Initializer Strategy

When you want to create your own strategy you will implement the IDatabaseInitializer interface and create your desired initialization behavior. Since all the colleague wanted was to drop the database tables during the application initialization and then to create all the relevant tables here is a sample code that can perform that:

1px solid;padding-top:4px;"> style="color:#0000ff;">public class DropCreateDatabaseTables : IDatabaseInitializer<Context> { #region IDatabaseInitializer<Context> Members "> public void InitializeDatabase(Context context) { bool dbExists; using (new TransactionScope(TransactionScopeOption.Suppress)) { dbExists = context.Database.Exists(); } if (dbExists) // remove all tables context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = \"DROP TABLE ?\""); "> // create all tables var dbCreationScript = ((IObjectContextAdapter)context).ObjectContext.CreateDatabaseScript(); context.Database.ExecuteSqlCommand(dbCreationScript); Seed(context); context.SaveChanges(); } else { throw new ApplicationException("No database instance") } } #endregion #region Methods protected virtual void Seed(Context context) { /// TODO: put here your seed creation } "> #endregion }

So what am I doing in the code sample?
At first I check that the the database exists if not an exception will be thrown. If the database exists I use a not documented SQL Server stored procedure which is sp_MSforeachtable in order to drop all the existing tables. After that, I get the context’s underlining ObjectContext in order to get the script that will generate the database using the CreateDatabaseScript method. Then, I run the script using the ExecuteSqlCommand method. After that I run the Seed method in order to enable the insertion of seed data into the database.

Another thing that you will need to do is to supply the relevant connection string for the existing database:

      <connectionStrings>

          <add name="Context" connectionString="Data Source=Server Name;Initial Catalog=Database Name;Persist Security Info=True;User ID=Username;Password=Password" providerName="System.Data.SqlClient"/>

      </connectionStrings>

Pay attention that when such a strategy is deployed whenever the application start over all the database tables will be recreated! This strategy should only run once.
After the deployment with the previous strategy, my colleague deployed the application again with the default Code First database initialization strategy!

Using the Database Initializer Strategy

In order to use the initialization strategy in an ASP.NET MVC application all you have to do is to set the initializer. The best place to do that is in the Global.asax file in the Application_Start handler. You will use the SetInitializer method that exists in the Database class to wire up the strategy. Here is a code sample that show how to wire up the previous strategy:

      protected void Application_Start()

      {

          AreaRegistration.RegisterAllAreas();

          RegisterGlobalFilters(GlobalFilters.Filters);

          RegisterRoutes(RouteTable.Routes);

          Database.SetInitializer(new DropCreateDatabaseTables());

      }

Summary

In the post I showed you how to create a new database initializer strategy. The provided strategy isn’t a silver bullet solution for the problem I mentioned in the post’s prefix. The ADO.NET team is working on a migration feature for EF Code First that might provide a solution for such a scenario. In the meantime the strategy presented here helped my colleague to solve his problem.

Sela Dev. Days 2011

Gil Fink — Fri, 20 May 2011 19:19:42 GMT

Sela Dev. Days 2011

Next month, June 26-30, Sela is going to have a mini conference – Sela Dev. Days. In the conference you will have the opportunity to meet Israel and world lead experts and learn about the new and coming Microsoft technologies that everyone will talk about in the next following years. The conference includes 25 one day workshop in subjects such as Silverlight 5, Parallel programing, Windows Phone Mango, ASP.NET MVC 3 and more.
In the conference I’m having the following three workshop days:

ASP.NET MVC 3, EF Code First integration, and Razor: Oh My!
ASP.NET MVC is a mature Microsoft web platform that enables the creation of quality web applications by using the MVC pattern. ASP.NET MVC 3 facilitates separation of concerns, total control over content generation using its built-in view engines and full support for test-driven development. In this one day tutorial you will get to know the framework and how to use it.
HTML 5
HTML is the markup language that every web developer uses to structure and present content in the Internet. HTML5 is the standard that is being shaped and developed currently. It extends and improves the last HTML4 standard and takes it to the next level with multimedia, communication support and more. In this one day tutorial you will get to know what is HTML5 and how you can use it even now in your web applications/sites.
Entity Framework 4.1 and Code First
Entity Framework is the new ORM and data access technology introduced by Microsoft. Entity framework provides an easy and efficient mapping from relational data into business entities. It is easy to use and it is integrated with many other Microsoft technologies. The ADO.NET Entity Framework is designed to enable developers to create data access applications by programming against a conceptual application model instead of programming directly against a relational storage schema. This one day tutorial will deep dive into EF4 and will also include an introduction to EF4.1 with Code First approach.

I recommend to attend all the workshops in the conference but these are the workshops that I would have chosen if I could attend the conference as an attendee:

I hope to see you there!

Not Just a Designer: Code First in Entity Framework Article on VS Magazine

Gil Fink — Tue, 03 May 2011 20:08:02 GMT

Not Just a Designer: Code First in Entity Framework Article on VS Magazine

Lately I wrote an article about Code First approach in Entity Framework 4.1 for Visual Studio Magazine. The article was published a few days ago and you can read it here.

Enjoy!

Spreading Inheritance Tree Mapping Across Assemblies in Code First

Gil Fink — Sun, 17 Apr 2011 20:09:43 GMT

Spreading Inheritance Tree Mapping Across Assemblies in Code First

Today I helped a client to solve a problem regarding EF4.1 Code First. The issue that they banged their heads with was an inheritance tree mapping in their model which is spread across two different assemblies. When they run the application they always got the same exception – “mapping and metadata information could not be found for entitytype ‘entity name’”. So they sent me a sample solution and I checked it and gave them the solution.

The Client Provided Model

In one class library there are the following two classes:

       namespace CodeFirstTest

      {

          public class Base

          {

              public int Id { get; set; }

          } 

          public class DeriveB : Base

          {

          }

      }

In another console application there is another derived class for the Base class:

      namespace CodeFirstTest

      {

          public class DeriveA : Base

          {

          }

      }

Also, in the same console application they have created the context:

      namespace CodeFirstTest

      {

        public class TheContext : DbContext

        {

          public TheContext()

          {

          }

          public DbSet<Base> MyModel { get; set; }

        }

      }

Running the following code will produce the “mapping and metadata information could not be found for entitytype ‘entity name’” exception:

      namespace CodeFirstTest

      {

        class Program

        {

          static void Main(string[] args)

          {

            Database.SetInitializer<TheContext>(new DropCreateDatabaseIfModelChanges<TheContext>());

            using (TheContext ctx = new TheContext())

            {

              var obj1 = new DeriveA();

              ctx.MyModel.Add(obj1);

              var obj2 = new DeriveB();

              ctx.MyModel.Add(obj2);

              obj2 = new DeriveB();

              ctx.MyModel.Add(obj2);

              ctx.SaveChanges();

            }

            using (TheContext ctx = new TheContext())

            {

              var res = ctx.MyModel.Where(b => b.Id == 2).SingleOrDefault();

            }

          }

        }

      }

The Solution

First I reproduced the exception and then tried to figure out what might be the mapping error that they get. Since the problem is in the entity type mapping then it must be caused by things like:

Type mismatches
Misspelled properties
Properties that are missing
More

The solution to the problem is to add mapping to all the entities in the context. In order to do that you will have to override the OnModelCreating method and map all the entities:

      protected override void OnModelCreating(DbModelBuilder modelBuilder)

      {

        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Base>();

        modelBuilder.Entity<DeriveA>();

        modelBuilder.Entity<DeriveB>();

      }

This solves the problem and produces the relevant database when the console application is running.

Summary

It took me a short period of time in order to find the mapping problem that my client had. The solution for the problem is simple but I would expect that Code First will supply the solution within. Maybe in vNext…

MIX11 Second Day Sessions Summary

Gil Fink — Thu, 14 Apr 2011 11:46:09 GMT

MIX11 Second Day Sessions Summary

Here is a summary of the sessions I attended in the second day of MIX11:

An Overview of the MS Web Stack of Love

In the session Scott Hanselman showed a lot of demos in the Microsoft web platform.
The things that Scott showed:

ASP.NET MVC 3 + new tools

Scaffolding

IIS Express
NuGet
EF4.1
Glimpse – a new open source package which is FireBug like tool for MVC framework.
Get the insight of the flow of your MVC application.

Knockout.js: Helping you build dynamic JavaScript UIs with MVVM and ASP.NET

Steve Sanderson presented a small introduction to knockout.js library. The library enables rich client-side interactivity, MVVM pattern and wide browser support. What it does is automatic dependency tracking, declarative binding and integrated templating. You can download the library from here.

Building Data-Centric N-Tier Applications with jQuery

Brad Olenick talked a little about what is coming in vNext for WCF Data Services which will include jQuery client, AppFabric integration and rich OData support. Then Brad presented the jQuery client for WCF Data Services – RIA/JS.

RIA/JS is available in two ways:

Scaffolding

Steve Sanderson explained what is scaffolding (generating code to make the process of development faster) and then deep dive into demos of GUI scaffolding, command-line scaffolding, T4 templates customization and more.

Reactive Extensions for JavaScript (RxJS)

Brat De Smet talked about a new JavaScript library that introduces JavaScript observable sequences and observers which help to implement the asynchronous programming with abstraction to scenarios like timers, XMLHTTPRequests, jQuery Ajax requests and more.

This is it for the second day of MIX11.