Rolling back from flask-restplus reqparse to native flask request to parse inputs

Created: July 16, 2020  |  1 minute read

flask-restplus’ (or flask-restx) reqparse module is deprecated, so I decided to use the native flask request object to parse the incoming inputs.

After the try, I noticed some points to take care of. Before listing these points, I will show you how to use native flask request to parse the inputs.

The flask-restplus official doc suggests to use marshmallow to replace reqparse.

Parsing inputs with the native flask request

The native Flask Request object has many attributes. To parse the incoming inputs, we can mainly use:

from flask import request
request.args
request.json
request.data
request.form
request.headers
request.authorization

request is a global object always available in any active request contexts.

Point 1. Smart boolean type

flask-restplus’s boolean type is actually a smart boolean type, which can convert bool True, or string “True”, “tRue”, “1” etc., or int 1 to True, so as to False. This is very smart.

parser.add_argument('flag', type=inputs.boolean)

When I rolled back to using the flask.request, there’s no such smartness, so be careful how the API parsed the inputs with flask-restplus previously. If it accepted for example the string ‘false’ as smart boolean, which will be converted to boolean False with flask-restplus, once migrated to the native flask.request.json, the string ‘false’ is considered as a boolean True.

>>> bool("false")
True

So maybe as a quick backward compatible workaround, we can reuse the smart boolean source code.

Point 2. Optional inputs

flask-restplus can define an optional input like this:

parser.add_argument('name', required=False, help="Name cannot blank!")

If user doesn’t provide name in the inputs, the reqparse will render it as {"name": None}, which means the optional input has None as its default value.

But in the native flask.request.json, we won’t see this input at all if it was not provided. So if the API backend must need the input name, we must add some protection.

Tests

In the end, I would just like to suggest everyone to write as many tests as we can to cover all the use cases.

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