[New Feature] Rest API implementation to showcase the OpenDBM features

rest_api/app/utils/app_exceptions.py

@@ -0,0 +1,51 @@
+from fastapi import Request
+from starlette.responses import JSONResponse
+
+
+class AppExceptionCase(Exception):
+    def __init__(self, status_code: int, context: dict):
+        self.exception_case = self.__class__.__name__
+        self.status_code = status_code
+        self.context = context
+
+    def __str__(self):
+        return (
+            f"<AppException {self.exception_case} - "
+            + f"status_code={self.status_code} - context={self.context}>"
+        )
+
+
+async def app_exception_handler(request: Request, exc: AppExceptionCase):
+    return JSONResponse(
+        status_code=exc.status_code,
+        content={
+            "app_exception": exc.exception_case,
+            "context": exc.context,
+        },
+    )
+
+
+class AppException(object):
+    class FooCreateItem(AppExceptionCase):
+        def __init__(self, context: dict = None):
+            """
+            Item creation failed
+            """
+            status_code = 500
+            AppExceptionCase.__init__(self, status_code, context)
+
+    class FooGetItem(AppExceptionCase):
+        def __init__(self, context: dict = None):
+            """
+            Item not found
+            """
+            status_code = 404
+            AppExceptionCase.__init__(self, status_code, context)
+
+    class FooItemRequiresAuth(AppExceptionCase):
+        def __init__(self, context: dict = None):
+            """
+            Item is not public and requires auth
+            """
+            status_code = 401
+            AppExceptionCase.__init__(self, status_code, context)