02 beginning code first
- 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
- 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
- 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; } }
- 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
- 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
- 24. ©2013 Microsoft Corporation. All rights reserved. Microsoft, Windows, Office, Azure, System Center, Dynamics and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
Editor's Notes
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