I'm trying to pass sorted dictionary to jsonify() function and then use it from within JS code to take out values. What I see there is that even though I pass correct values, they are reordered by jsonify for some reason.

json_data = {
    "11": {
        "j_id": "out",
    },
    "aa": {
        "j_id": "in",
    },
    "bb": {
        "j_id": "out",
    },
}

jkeys=json_data.keys()
sorted_json = sorted(jkeys, key=lambda x: json_data[x]['j_id'], reverse=False)

new_sorted=OrderedDict()
for rec in sorted_json:
    new_sorted[rec]=json_data[rec]

print('sort dict: {}'.format(new_sorted))

The output is correct and I can see proper values which in my case should be: aa, 11, bb

>>> from collections import OrderedDict
>>>
>>> json_data = {
...     "11": {
...         "j_id": "out",
...     },
...     "aa": {
...         "j_id": "in",
...     },
...     "bb": {
...         "j_id": "out",
...     },
... }
>>>
>>> jkeys=json_data.keys()
>>> sorted_json = sorted(jkeys, key=lambda x: json_data[x]['j_id'], reverse=False)
>>>
>>> new_sorted=OrderedDict()
>>> for rec in sorted_json:
...     new_sorted[rec]=json_data[rec]
...
>>> print('sort dict: {}'.format(new_sorted))
sort dict: OrderedDict([('aa', {'j_id': 'in'}), ('11', {'j_id': 'out'}), ('bb', {'j_id': 'out'})])

Unfortunately, when I pass this to jsonify() function and then for example console.log() output of flask data, the orderd becomes like that: 11, aa, bb. Additionally to that, I've done some research and found this stackoverflow answer, leading to some good documentation notes which clearly states that setting JSON_SORT_KEYS to False is not recommended way. Then I checked this github issue and it seems that problem is not fully resolved in flask.

What would be the best way to fix it in my case?

Add this config line to your code after the app definition:

app = Flask(__name__)
app.config['JSON_SORT_KEYS'] = False