EF Core .NET 6 - Access DbContext from singleton service
Hi,
I've started using EF Core (.NET 6) since a few weeks, but I'm a bit confused about the following aspects:
- I keep reading the dbContext should be scoped, and that make sense.
- If I want service A to access dbContext, service A needs to be scoped as well, it cannot be a singleton. And I could understand this: since a service in injected in the constructor, A needs to be re-instantiated every time it needs to access dbContext so that each time a new instance of dbContext is injected into it
- Controllers are transient (or scoped, not sure), so when a request come, the controller is instantiated passing to it a service A instance which in turn is instantiated on the fly passing an instance of dbcontext to it.
Until here everything makes sense.
I have a scenario where I have a long-running task (singleton service B) that periodically needs to write data to the database. How am I supposed to do this, since I cannot inject scoped service A into singleton service B?
From this post https://stackoverflow.com/a/58989132/7035167 it seems like I should have a factory of service A objects and, everytime B needs to access database, I should generate an instance of A, use it to write on database and then dispose it.
However it seems to me that this defeats the whole purpose of the dependency injection concept: from what I've understood, I should not instantiate an object that is injected somewhere else. Furthermore, if I was to instantiate service A, I should first instantiate dbContext too, and I think this is not the correct way of doing things.
I've started using EF Core (.NET 6) since a few weeks, but I'm a bit confused about the following aspects:
- I keep reading the dbContext should be scoped, and that make sense.
- If I want service A to access dbContext, service A needs to be scoped as well, it cannot be a singleton. And I could understand this: since a service in injected in the constructor, A needs to be re-instantiated every time it needs to access dbContext so that each time a new instance of dbContext is injected into it
- Controllers are transient (or scoped, not sure), so when a request come, the controller is instantiated passing to it a service A instance which in turn is instantiated on the fly passing an instance of dbcontext to it.
Until here everything makes sense.
I have a scenario where I have a long-running task (singleton service B) that periodically needs to write data to the database. How am I supposed to do this, since I cannot inject scoped service A into singleton service B?
From this post https://stackoverflow.com/a/58989132/7035167 it seems like I should have a factory of service A objects and, everytime B needs to access database, I should generate an instance of A, use it to write on database and then dispose it.
However it seems to me that this defeats the whole purpose of the dependency injection concept: from what I've understood, I should not instantiate an object that is injected somewhere else. Furthermore, if I was to instantiate service A, I should first instantiate dbContext too, and I think this is not the correct way of doing things.
Stack Overflow
I need to access my database in a Singleton class instantiated in my Startup class. It seems that injecting it directly results in a DbContext that is disposed.
I get the following error:
Cannot
I get the following error:
Cannot
