EF.Interception is small library that lets you intercept saving of entities in Entity Framework.

Install the plugin from NuGet: Install-Package EF.Interception.

To enable interception, derive your database context from InterceptionDbContext instead of DbContext:

public class MyDbContext : InterceptionDbContext
{
    // -- SNIP --
}

You can then add interceptors by calling AddInterceptor. An interceptor must derive from Interceptor<T>:

public class AuditInterceptor : Interceptor<IAuditEntity>
{
    public override void PreInsert(IContext<IAuditEntity> context)
    {
        context.Entity.CreatedAt = DateTime.UtcNow;
        context.Entity.ModifiedAt = DateTime.UtcNow;
    }

    public override void PreUpdate(IContext<IAuditEntity> context)
    {
        context.Entity.ModifiedAt = DateTime.UtcNow;
    }
}

public class MyDbContext : InterceptionDbContext
{
    public MyDbContext()
    {
        AddInterceptor(new AuditInterceptor());
    }
}

Interceptor<T> has six methods you can override:

• PreInsert
• PreUpdate
• PreDelete
• PostInsert
• PostUpdate
• PostDelete

All methods takes an IContext<T> which has three properties:

• Entity - The entity which is intercepted.
• State - The entity's current state. This can be altered.
• ValidationResult - The entity's validation result.