The document discusses Code First, an approach in Entity Framework for defining a model and mapping it to a database. It covers creating classes, adding attributes for database mapping, creating a data context, and initializing the database. Code First allows defining classes as normal and uses conventions to map them to database tables, while attributes and the fluent API provide control over the mapping.

1. 02 | Beginning Code First
Adam Tuliper | Technical Evangelist
Christopher Harrison | Content Developer

2. • Simple Code First
• Creating classes
• Creating Data Context
• Initializing the database
Code First

3. Simple Code First

4. public class Artist
{
public int ArtistID { get; set; }
public string Name { get; set; }
public string Bio { get; set; }
}

5. Code first classes…
are just classes

6. Code first class design tips
• Just design your classes the way you typically would
– (for the most part)
• Use standard conventions
– ID for the ID
• You can still control the database
– Attributes
– Fluent API

7. Creating classes

8. But what about my database?
• Code First often does the right thing
• But it does need a little guidance
• For example, strings become nvarchar(max)

9. Basic database control
• Data annotations can be used to provide additional context
– System.ComponentModel.DataAnnotations
– https://msdn.microsoft.com/en-
us/library/system.componentmodel.dataannotations(v=vs.110).aspx
• Not specific to Entity Framework
– Used by several other platforms, including MVC

10. Code First conventions
• Tables are automatically pluralized
• Tables are created in the dbo schema
• ID property is created as the primary key
– Identity or auto-count column

11. Table creation
• TableAttribute
– Schema
– Name
• ColumnAttribute
– Name

12. Strings
• Nullable nvarchar(max) is the default
• Attributes
– StringLengthAttribute
• MaximumLength
• MinimumLength
– RequiredAttribute

13. Numbers
• SQL data type is mapped to .NET data type
– long becomes BigInt
• RangeAttribute
– Maximum
– Minimum

14. Value types and nullability
• Dates and numbers are value types in .NET
• Value type properties must be marked as nullable
– Nullable<T>
– type?

15. DEMO
Attributes and database control
(warning... This demo is going to fail. Well, sort of.)

16. Creating the Data Context

17. Creating the Data Context
• Just like creating a normal class
– It's like it's called Code First 
public class MusicStoreDbContext : DbContext
{
public DbSet<Artist> Artists { get; set; }
}

18. DEMO
Creating the DbContext

19. The Find() method
• Regardless of the data type you're going to need to look the
object up by its key
• Rewriting that code over and over again becomes tedious
• The Find method will do that for you
• Accepts a parameter that maps to the key
• Returns the object if it's found
• Returns null if it isn't

20. DEMO
Creating a repository

21. Initializing the database

22. Testing requires a known starting state
• Entity Framework provides database initializers to create that
state
• Create a class that inherits from the appropriate option
– CreateDatabaseIfNotExists
– DropCreateDatabaseWhenModelChanges
– DropCreateDatabaseAlways
• Override the Seed method to create database content
• Register the method with Database.SetInitializer

23. DEMO
Initializing the database

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