Read Only DbContext

Typically in a CQRS model, your read models are not meant to be used for creating or updating state in the database. They're meant to be read-only. In fact, you don't even want to take advantage of the EntityFramework change tracking.

There are 2 ways of doing read-only DbContexts; inheritance or using the registration methods that will configure without having to use inheritance.

ReadOnlyDbContext base class

The ReadOnlyDbContext base class gives you a base class that also inherits from the BaseDbContext to give you the common tools.

All you need to do for your DbContext is to inherit from it as shown below:

using Cratis.Applications.EntityFrameworkCore;

public class StoreDbContext : ReadOnlyDbContext
{
    public DbSet<Customer> Customers { get; set; }
}

Then you register it as you normally would:

services.AddDbContext<StoreDbContext>(opt => ...);

Register

The other option is to let you inherit from whatever base DbContext you want and then instead leverage the extension methods:

services.AddReadOnlyDbContext<StoreDbContext>(opt => ...);

Discover and register all in assemblies

For convenience you can get all types inheriting from DbContext automatically discovered and registered in one call.

services.AddReadModelDbContextsFromAssemblies(opt => 
{
    /* Configure any options */
},
[Assembly.GetExecutingAssembly()]);

Or if you want it to automatically configure it with the correct database:

services.AddReadModelDbContextsWithConnectionStringFromAssemblies(opt => 
{
    /* Configure any options */
},
".. your connection string..",
[Assembly.GetExecutingAssembly()]);