[FIXED] Cannot Receive Unicode Value from input on Python-Flask

Issue

My Sample Python Script is like this:

# -*- coding: utf-8 -*-
from flask import *

app = Flask(__name__)


@app.route('/', methods=['GET','POST'])
def checkName():
    if request.method=='POST':
        namekh = request.form['KhmerName']

        print "Khmer name is ",namekh
        if isinstance(namekh.encode('utf8'), unicode):
            return render_template('hello.html', Name=namekh)
        else:
            namekh = 'Please enter khmer character only'
            return render_template('hello.html', Name=namekh)


    return render_template('hello.html')

if __name__ == '__main__':

    app.run(debug=True)

From script above, I tried to received input value from form element name KhmerName on submit and check if it is a Unicode Character or not. Then I send it to display at my html markup hello.html.

The html is look like this:

{% if Name %}
    <p>Hello, {{Name}} wellcome to mysite</p>
{% endif %}
<form class="form-horizontal" action='' method='POST'>
  <div class="form-group">
    <label for="KhmerName" class="col-sm-2 control-label">Khmer Name:</label>
    <div class="col-sm-10">
      <input type="text" class="form-control" id="KhmerName" name="KhmerName" placeholder="KhmerName">
    </div>
  </div>
  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <button type="submit" class="btn btn-default">Submit</button>
    </div>
  </div>
</form>

However, my problem is that if KhmerName is kind of None-Character is it working fine, yet it is an Unicode Character, it will return an error message

UnicodeEncodeError: 'charmap' codec can't encode characters in position 0-4: character maps to <undefined>

Traceback (most recent call last)
File "C:\Python27\lib\site-packages\flask\app.py", line 1997, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Python27\lib\site-packages\flask\app.py", line 1985, in wsgi_app
response = self.handle_exception(e)
File "C:\Python27\lib\site-packages\flask\app.py", line 1540, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Python27\lib\site-packages\flask\app.py", line 1982, in wsgi_app
response = self.full_dispatch_request()
File "C:\Python27\lib\site-packages\flask\app.py", line 1614, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Python27\lib\site-packages\flask\app.py", line 1517, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "C:\Python27\lib\site-packages\flask\app.py", line 1612, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Python27\lib\site-packages\flask\app.py", line 1598, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "F:\python\check Unicode\hello.py", line 12, in hello_world
print "Khmer name is ",namekh
File "C:\Python27\lib\encodings\cp437.py", line 12, in encode
return codecs.charmap_encode(input,errors,encoding_map)
UnicodeEncodeError: 'charmap' codec can't encode characters in position 0-4: character maps to <undefined>

What I did to check the Unicode here is by using isinstance(namekh.encode('utf8'), unicode), so it should working (return true) because the type of namekh was already an unicode type if an input value was an unicode character. Yet, I had no idea why it return an error like above.

Solution

I have test on a demo project. The type of variable return from request.form["key"] is unicode. So you needn't transform it to unicode from str use decode. I also test សួរស្តីរ on the demo project, it can be printed. From the code you provide. You might want to only allow the khmer character. I think you use regex to test the input.

REGEX_KHMER = u"[\u1780-\u17dd\u17e0-\u17e9\u17f0-\u17f9]+"

if re.match(REGEX_KHMER, namekh):

    return correctly

else:

    return enter khmer character only

Answered By - stamaimer