Get request data from the front end to flask is handled perfectly fine at the local host but not in the server

Question

I am using this code to send data to the front end and then redirect it to another function.

@app.route('/get_destination_data', methods=['GET', 'POST'])
def get_destination_data():
    data = request.get_json()
    return jsonify({'redirect': url_for("show_destination_info", city_info=data)})

@app.route('/show_destination_info/<city_info>', methods=['GET', 'POST'])
def show_destination_info(city_info):
    return render_template('city-info.html', data=eval(city_info),
                           lists=UserLists.query.filter_by(user_id=current_user.id).all())

The second function is supposed to receive the date thru the url which gets converted to dictionary. This works perfectly fine in the local host. The data which I receive is a string that looks like this {'city_name': 'London', 'country_name': 'United Kingdom', 'id': 27456, 'state_prov': 'England'} and is easy to handle later.

In the server however I am getting this error message:

[2023-08-20 09:34:00,431] ERROR in app: Exception on /show_destination_info/%7B'city_name':%20'London',%20'country_name':%20'United%20Kingdom',%20'id':%2027456,%20'state_prov':%20'England'%7D [GET]
Traceback (most recent call last):
  File "/home/rabotataco/virtualenv/cgi-bin/www/3.9/lib/python3.9/site-packages/flask/app.py", line 2190, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/rabotataco/virtualenv/cgi-bin/www/3.9/lib/python3.9/site-packages/flask/app.py", line 1486, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/rabotataco/virtualenv/cgi-bin/www/3.9/lib/python3.9/site-packages/flask/app.py", line 1484, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/rabotataco/virtualenv/cgi-bin/www/3.9/lib/python3.9/site-packages/flask/app.py", line 1469, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "/home/rabotataco/virtualenv/cgi-bin/www/3.9/lib/python3.9/site-packages/flask_login/utils.py", line 290, in decorated_view
    return current_app.ensure_sync(func)(*args, **kwargs)
  File "/home/rabotataco/cgi-bin/www/proj1/routes_user.py", line 175, in show_destination_info
    return render_template('user_city-info.html', data=eval(city_info),
  File "<string>", line 1
    %7B'city_name':%20'London',%20'country_name':%20'United%20Kingdom',%20'id':%2027456,%20'state_prov':%20'England'%7D
    ^
SyntaxError: invalid syntax

the next to the last line is actually the header which is same as the one in my localhost but for some reason same code in the server cant handle this type of data.

could somebody help me please? What would be the possible solution here?

Answer 1

I found a solution that works for me. I am not sure if this is the right approach but it does trick. The problem is that URLs are not always decoded as expected in WSGI environment. this is why I'm getting the url as it is and slice only the part I need.

@app.route('/get_destination_data', methods=['GET', 'POST'])
def get_destination_data():
    wholeurl = request.url
    baseurl = request.base_url
    data = {'redirect': '/show_destination_info'+wholeurl[len(baseurl):]}
    return data


@app.route('/show_destination_info', methods=['GET', 'POST'])
def show_destination_info():
    data = request.values
    return render_template('city_info.html', data=data)