![]() The classes defined within the source code become the model. If you attempt to insert multiple Users having the same UserName you'll get a DbUpdateException with the following message: Cannot insert duplicate key row in object 'dbo.Users' with unique index 'Index'.Īgain, column annotations are not available in Entity Framework prior to version 6.1. Code First Using the Entity Framework Code First modeling path, developers define the application domain model using source code rather than working directly with a designer or an XML-based configuration file. ![]() This will create the following SQL script: CREATE UNIQUE NONCLUSTERED INDEX ON. Property(x => x.Name).IsRequired().HasMaxLength(450).HasColumnAnnotation("Index", new IndexAnnotation(new As they are, the Blog and Post classes conveniently follow code first convention and require no tweaks to enable EF compatability. If you use Fluent: public class UserMap : EntityTypeConfiguration I’ll demonstrate Code First DataAnnotations with a simple pair of classes: Blog and Post. DataAnnotations are also understood by a number of. Your model will look like this now in EF CF 6.1+: public class User DataAnnotations is used to configure the classes which will highlight the most commonly needed configurations. ![]() You can solve this by setting a maximum string length on your model: SQL Server retains the 900-byte limit for the maximum total size of all index key columns." If your model field is a string, make sure it is not set to nvarchar(MAX) in SQL Server or you will see this error with Entity Framework Code First:Ĭolumn 'x' in table 'dbo.y' is of a type that is invalid for use as a key column in an index. You can find it in this namespace: using In this tutorial, you will add data annotations to restrict the length of the values provided for the FirstName, LastName, and MiddleName properties. In Entity Framework 6.1+ you can use this attribute on your model:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |