如何在Flask API中返回一个通用的JSON对象？

Question

I'm building an API that returns JSON strings. My goal, however, is to have a common wrapper around results that contain various meta data attributes about the returned results, plus the return results.

• Total number of results (I don't allow a user to query for more than 1000 at a time, so they need to know if there is more so they can request the next set of results)
• Throttle time (tells the user to back off for a period of time before the next request - useful if the API is busy)
• Error code/Message
• Data user requested

My JSON object would look something like this:

{
    'total_results': 1001,
    'throttle': 0,
    'error_cd': 0,
    'message': 'Successful',
    'results': [
        # Data that is returned; Each end point can return a different "type"
        ]
}

The goal is to have my end points simply return the data that appears in results (not even in JSON format). My question is how can I provide a wrapper around this?

My initial idea was a decorator of some kind that runs jsonify , but can a decorator run AFTER a function? IE. Can I run the code in my route and THEN run decorator code?

Answer 1

What about just writing a wrapper function? I would probably do something like:

 @app.route('/api/blah/')
 def my_route():
     results = calculate_my_results()
     return jsonify(format_api_result(results))

 def format_api_result(data):
     # add in your extra metadata here, return a dictionary

A function seems to me to be the most straightforward and most flexible way to do what you want. It's a little extra code, but so's a decorator. And while you can certainly do this in a decorator, I don't think it adds much here except complexity.

If you do want to go the decorator route, check out this:

http://www.jeffknupp.com/blog/2013/11/29/improve-your-python-decorators-explained/

for a good explanation of how decorators work and how you control exactly when the wrapped function gets called.

Let me know if I misunderstood what you're trying to do.