Is there any good solution for this example?
Seems like if I have a lot of modules like photo.module.ts I need to import DatabaseModule in every feature module.
Tried to put it in app.module.ts but it doesn't help. Maybe there are some solutions with forRoot static import?
As it says in the docs:
In this article, you'll learn how to create a DatabaseModule based on the TypeORM package from scratch using custom providers mechanism. As a consequence, this solution contains a lot of overhead that you can omit using ready to use and available out-of-the-box dedicated @nestjs/typeorm package.
So better use the @nestjs/typeorm package, see docs.
When you use the @nestjs/typeorm package, you have to import TypeOrmModule.forFeature([PhotoEntity]) for each feature module. In each feature module, you only want to register the entities that belong to that feature. This improves the encapsulation.
You tried to register a module in the AppModule and wondered why its providers weren't available in the feature modules. Note that a module always has to import a module itself so that it can access its exported providers. The only exception to this are global modules. When you annotate a module with the decorator @Global() then it will automatically be imported in all modules as long as it is imported at least once (e.g. in your AppModule).