Entity Framework Auto Generate GUID with Code Examples

When building modern applications, managing unique identifiers for database records is crucial. One widely used method for this is using Globally Unique Identifiers (GUIDs). In this blog post, we will explore how to leverage Entity Framework to automatically generate GUIDs for your entities, saving you time and effort in managing primary keys.

What is a GUID?

A GUID, or Globally Unique Identifier, is a 128-bit number that guarantees uniqueness across all devices and systems worldwide. It is often represented as a string of 32 hexadecimal digits, separated by hyphens, for readability.

Benefits of Using GUIDs

Uniqueness: GUIDs are virtually guaranteed to be unique, even when generated independently on different systems.
No Collision Concerns: Unlike incremental integers, you don't have to worry about potential collisions when merging data from multiple sources.
Replication and Syncing: GUIDs simplify data replication and synchronization across distributed databases.
Security: GUIDs make it difficult for malicious actors to predict or guess the next identifier.

Generating GUIDs Automatically with Entity Framework

Entity Framework allows us to automatically generate GUIDs for specific properties using the DatabaseGenerated attribute combined with the Guid data type.

public class MyEntity
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid Id { get; set; }

    // Other properties...
}

In the example above, the Id property serves as the primary key and will be manually assigned a GUID, while the AutoGeneratedGuid property will be automatically assigned a new GUID by the database when inserting a new record.

Configuring GUID Generation in Code-First Migrations

When using Code-First Migrations, you need to configure the GUID generation behavior in the migration configuration file.

public Configuration : DbMigrationsConfiguration<MyDbContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = false;
        SetSqlGenerator("System.Data.SqlClient", new SqlServerMigrationSqlGenerator());
        CodeGenerator = new EntityModelCodeGenerator();
    }

    protected override void Seed(MyDbContext context)
    {
        // Seed data or other configuration...
    }
}

Generating GUIDs in Database-First Approach

If you're using the Database-First approach, you can set the GUID generation in the database itself. For Microsoft SQL Server, you can use the NEWID() function in the default value of the column.

CREATE TABLE MyEntities
(
    Id UNIQUEIDENTIFIER PRIMARY KEY,
    AutoGeneratedGuid UNIQUEIDENTIFIER DEFAULT NEWID(),
    -- Other columns...
)