Introduction to MVC 4 04. Adding Model Classes

1. Introduction to MVC 404. Adding Model Classes NTPCUG Tom Perkins, Ph.D.

2. Classes built thus far … • Controller • Handles incoming browser requests • Retrieves data from Model classes • Specifies View templates to return HTML to the browser • View • Dynamically generates HTML requests • Now … Model classes • Represents the data in the application • Use business logic to enforce business rules for data

3. Entity Framework (EF) • .NET Framework data access technology • Code First paradigm • Create model objects by writing simple classes • Called “POCO” classes – “Plain Old CLR Objects” • Database is created “on the fly” from your classes

4. Creating Model Classes (Approach) • Create a class to represent a Movie entity • A database will be created using the Movie class to develop its schema • Each instantiation (object) of the class will correspond to a row in a database • Properties in the class will correspond to columns in the database

5. Entity Framework – CodeFirst Paradigm Class Database Class (object) maps to a row Class (object) Property xxx Property xxx Property xxx . . . Property xxx Properties map to Columns in the database

6. Add Model Classes Right-Click Select Select

7. Name the class Click

8. Add 5 properties to the Movie class … public class Movie { public int ID { get; set; } public string Title { get; set; } public DateTimeReleaseDate { get; set; } public string Genre { get; set; } public decimal Price { get; set; } } • Each object corresponds to a row in the table • Each property corresponds to a column in the table

9. Add the MovieDBContext class to the same Movie.cs file • MovieDBContext class handles • Fetching Movie entities from database • Storing Movie entities into database • Updating Movie entities in database • Derives from DBContext base class in Entity Framework public class MovieDBContext : DbContext { public DbSet<Movie> Movies { get; set; } }

10. Add the following using statement to the top of the file • Needed to reference (later) • DbContext • DbSet using System.Data.Entity;

11. The complete Movie.cs file using System; using System.Data.Entity; namespace MvcMovie.Models { public class Movie { public int ID { get; set; } public string Title { get; set; } public DateTimeReleaseDate { get; set; } public string Genre { get; set; } public decimal Price { get; set; } } public class MovieDBContext : DbContext { public DbSet<Movie> Movies { get; set; } } }

12. Connecting to a local SQL Server Compact Database • The MovieDBContext class just created handles: • Connecting to the database • Mapping Movie objects to database records • How to specify which database to connect to? • Add connection information to Web.config file • (Note) – use Web.config in the website root, not the Web.config in the Views folder.

13. Open the application root Web.config file Click

14. Add the following connection string to the <connectionStrings> element in the Web.config file: • Expanded view of connection string literal-Enter it with no spaces or carriage returns: <add name="MovieDBContext" connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\Movies.mdf;Integrated Security=True" providerName="System.Data.SqlClient" /> <add name="MovieDBContext" connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\Movies.mdf;Integrated Security=True" providerName="System.Data.SqlClient" />

15. The resulting Web.config file: <connectionStrings> <add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=aspnet-MvcMovie-2012213181139;Integrated Security=true" providerName="System.Data.SqlClient" /> </connectionStrings> Now, Build the application and correct any errors … <add name="MovieDBContext" connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\Movies.mdf;Integrated Security=True" providerName="System.Data.SqlClient" />

16. Module summary … • The Movies.cs class will • Represent Movie data • Store the Movie data in the database • Next – • Create a MoviesController class that will • Display the Movie data • Allow users to create new Movie listings