Persistence Ignorance

Persistence Ignorance is the principle that your domain objects should not know how they are saved to a database.

1. The EF Core Conflict

EF Core usually wants public setters and parameterless constructors. DDD wants private setters and rich constructors. To solve this, we use **Entity Configurations** in the Infrastructure layer. We use .HasField() and .UsePropertyAccessMode() to tell EF Core to use our private backing fields instead of our public properties.

2. Shadow Properties

Sometimes you need data for the database (like a Version column for concurrency) that the domain doesn't care about. You can define these as **Shadow Properties** in EF Core. They exist in the database and the DbContext, but they never appear in your C# Domain Entity. This keeps your domain pure.

3. Architect Insight

Q: "Should I use Data Annotations like [Key] in my Domain?"

Architect Answer: "NO. That is a violation of Clean Architecture because your Domain now depends on System.ComponentModel.DataAnnotations, which is a persistence detail. Always use the **Fluent API** in the Infrastructure layer's OnModelCreating to define your database schema. The Domain stays 100% POCO (Plain Old CLR Object)."