A question for core.Service

[FindBoat]

I got a quick question for core.Service. So what's the point to wrap sqlalchemy's methods into Service rather than call them directly in each application?

Also I didn't find a way to use some sqlalchemy's methods like (query.filter, concatenating multiple filter_by etc.) without calling directly model.query blabla. It seems that Service doesn't provide all methods of sqlalchemy.

[mattupstate]

@FindBoat Explained here

[FindBoat]

Thanks for the explanation. I think my second question is not answered. Actually I can't use some sqlalchemy's query method by calling Service methods. For instance, I want to query obj whose attr1=val1 and attr2=val2 or more complicated.
If I'm using obj.model.query, it seems to break the abstract of Service.

[mattupstate]

Nothing is stopping you from using the models directly, or creating a service method that abstracts the query you're trying to make. A hypothetical example:

class UserService(Service):

    def custom_method(self, email):
        return self.__model__.query.filter(self.__model__.email==email).all()

[FindBoat]

Well, I assume that Service abstracts external stuffs like sqlalchemy, and UserService should only call methods provided by Service. Thus in the future, suppose we want to migrate from sqlalchemy to something else, we only need to change the implementation of Service.

However, if we are calling sqlalchemy methods directly in UserService, it breaks the assumption above. Otherwise, what's the benefit to define a Service rather than using external stuffs directly.

[mattupstate]

Thats an assumption you have made for yourself. I've never suggested that custom service methods must use the methods provided by Service. It is by no means a complete abstraction on top of SQLAlchemy either. As described in the blog post, the service layer is to expose a logical API that encapsulates your platforms core logic. That service can then be used in multiple contexts such as a web app, or even a CLI if you wanted to build one on top of it.

[FindBoat]

I see. That make sense. Thank you very much Matt! Also thank you for sharing your insight on Flask.

[mattupstate]

No sweat! Appreciate the discussion.