Database.Migrate() creating database but not tables, EF & .NET Core 2

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06-10-2024

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EF Core 2: Database Migration Mysteriously Skipping Table Creation

You're excited to get your .NET Core 2 application up and running, but you hit a snag: Database.Migrate() successfully creates the database, but your tables are nowhere to be found! This common issue can be frustrating, but it's often resolved by understanding how Entity Framework Core (EF Core) handles database migrations.

The Scenario:

Imagine you have a simple .NET Core 2 application with a DbContext and some model classes:

public class MyDbContext : DbContext
{
    public DbSet<Product> Products { get; set; }

    public MyDbContext(DbContextOptions<MyDbContext> options) : base(options)
    {
    }
}

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}

You've created a migration using dotnet ef migrations add InitialCreate, and everything seems in order. Yet, when you run dotnet ef database update, the database is created, but no tables appear!

The Problem:

The issue lies in how EF Core handles migrations. While Database.Migrate() ensures the database exists, it doesn't automatically create the tables defined in your model classes. Instead, EF Core looks for existing migrations and applies them to the database.

Understanding the Solution:

To resolve this, you need to understand a few key points:

1. Initial Migration: Your first migration (InitialCreate) usually contains the table creation instructions. This is the starting point for your database structure.
2. Migration Application: Database.Migrate() looks for existing migrations in the Migrations folder. If it finds a migration matching the current database schema, it doesn't create new tables.
3. New Migration Required: If you've added new tables or modified existing ones, you need to create a new migration using dotnet ef migrations add <MigrationName> and then run dotnet ef database update.

Example:

Let's say you've added a new Customer model:

public class Customer
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

1. Create a new migration: dotnet ef migrations add AddCustomer
2. Apply the migration: dotnet ef database update

This process will add the Customer table to your database, ensuring your application's data model is synchronized with your database structure.

Additional Considerations:

• Database Existence: If the database already exists but has a different schema than your models, Database.Migrate() may fail. In such cases, you might need to manually create the tables or drop and recreate the database.
• Database Type: Some databases might have specific configuration options that influence table creation. Consult your database provider's documentation for details.

Conclusion:

Remember, Database.Migrate() doesn't magically create tables in EF Core. It's a tool for applying existing migrations to your database. By understanding this concept, you can effectively manage your database schema and avoid the pitfalls of missing table creation.