Add SQLAlchemy and database boilerplate code

tofu_api/common/rest/__init__.py

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+from .base_blueprint import BaseBlueprint

tofu_api/common/rest/base_blueprint.py

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+from abc import ABC, abstractmethod
+from typing import Callable, Type, TYPE_CHECKING
+
+from flask import Blueprint
+from flask.views import View
+
+if TYPE_CHECKING:
+    from tofu_api.app import App
+
+__all__ = [
+    'BaseBlueprint',
+]
+
+
+class BaseBlueprint(Blueprint, ABC):
+    """
+    Base class for Flask blueprints.
+    """
+
+    # Reference to the application object
+    app: 'App'
+
+    @property
+    @abstractmethod
+    def name(self) -> str:
+        """
+        The name of the blueprint. Will be prepended to each endpoint name.
+        """
+        raise NotImplementedError
+
+    @property
+    @abstractmethod
+    def import_name(self) -> str:
+        """
+        The name of the blueprint package. Should be set to `__name__`.
+        """
+        raise NotImplementedError
+
+    @property
+    @abstractmethod
+    def url_prefix(self) -> str:
+        """
+        Prefix for all URLs.
+        """
+        raise NotImplementedError
+
+    def __init__(self, app: 'App'):
+        """
+        Initialize blueprint. Needs the Flask application object.
+        """
+        super().__init__(
+            name=self.name,
+            import_name=self.import_name,
+            url_prefix=self.url_prefix,
+        )
+        self.app = app
+        self.init_blueprint()
+
+    @abstractmethod
+    def init_blueprint(self) -> None:
+        """
+        Register child blueprints and URL rules.
+        """
+        raise NotImplementedError
+
+    @staticmethod
+    def create_view_func(view_cls: Type[View], *args, **kwargs) -> Callable:
+        """
+        Helper function to create a view function from a `View` class using `view_cls.as_view()`.
+        All arguments are passed to the constructor of the view class.
+        """
+        return view_cls.as_view(view_cls.__name__, *args, **kwargs)