Your question touches on a common dilemma when designing Flask APIs: whether to use Flask-RESTful’s Resource-based approach or Flask’s route-based approach. Both are valid and have their place, depending on your use case and preferences.

Key Differences

1. Flask-RESTful (Resource):

   • Encourages object-oriented programming.
   • Suited for RESTful APIs where resources (entities like “users” or “orders”) map to URL endpoints.
   • Easily organizes logic for different HTTP methods (GET, POST, PUT, DELETE) using class methods.
   • Field ordering: Flask-RESTful does not sort JSON keys by default, which is why you observe unsorted fields.

   Example:

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   <code>class UserResource(Resource):

   def get(self):

   return {"name": "Alice", "age": 25} # Order preserved.

   </code>

   <code>class UserResource(Resource): def get(self): return {"name": "Alice", "age": 25} # Order preserved. </code>

   class UserResource(Resource):
       def get(self):
           return {"name": "Alice", "age": 25}  # Order preserved.
   

2. Route-based approach (@app.route):

   • Traditional and simpler to understand for Flask beginners.
   • Ideal for small applications or non-RESTful APIs where endpoints are procedural or one-off.
   • Field ordering: The jsonify function (implicitly used by Flask’s @app.route) sorts keys alphabetically by default when serializing to JSON.

   Example:

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   <code>@app.route("/user")

   def user():

   return {"age": 25, "name": "Alice"} # Alphabetically sorted as {"age": 25, "name": "Alice"}.

   </code>

   <code>@app.route("/user") def user(): return {"age": 25, "name": "Alice"} # Alphabetically sorted as {"age": 25, "name": "Alice"}. </code>

   @app.route("/user")
   def user():
       return {"age": 25, "name": "Alice"}  # Alphabetically sorted as {"age": 25, "name": "Alice"}.
   

Best Practices

1. When to Use Flask-RESTful:

   • Your application requires RESTful design principles.
   • You have multiple resources and endpoints that need organization.
   • You plan to expand the API or work in a team, and a class-based approach aids readability and maintainability.

2. When to Use Route-based:

   • The application is small, and adding Flask-RESTful is overkill.
   • Endpoints are limited in number and don’t require complex organization.
   • You prefer simplicity over the additional abstraction provided by Flask-RESTful.

Your Case

Since both methods lead to the same result and the only difference is the field ordering:

1. If you are building a RESTful API (e.g., for Azure integration or larger projects), stick with Flask-RESTful for its structure and scalability.
2. If this is a small utility or one-off endpoint, the route-based approach is perfectly fine.

About Field Ordering

The deviation in field ordering is due to:

• Flask-RESTful uses Python’s json library directly, which preserves insertion order for dictionaries.
• Route-based approach uses Flask’s jsonify, which applies sort_keys=True by default when dumping JSON.

If you want to control field ordering in the route-based approach, you can disable sorting like this:

from flask import jsonify

@app.route("/compute-route", methods=["GET"])
def execute():
    return jsonify(compute(request.args.to_dict())), 200, {"Content-Type": "application/json"}

Recommendation

For maintainability and scalability, especially when working with Azure or similar platforms, adopt Flask-RESTful with Resource. It aligns with REST API standards and keeps your code organized as the project grows.