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Editorial Team
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Asked: 2026-05-12T07:54:57+00:00

What I am trying to do is pretty simple: yet something has clearly gone

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What I am trying to do is pretty simple: yet something has clearly gone awry.

On the Front-End:

function eval() {
    var x = 'Unchanged X'
    $.get("/",  { entry: document.getElementById('entry').value },
          function(data){
            x = data;
          }
      );

       $("#result").html(x);
    }

On the Back-End:

class MainHandler(webapp.RequestHandler):

  def get(self):
      path = os.path.join(os.path.dirname(__file__), 'index.html')
      if self.request.get('entry') != '':
          #self.response.out.write({'evalresult': self.request.get('entry')})
          self.response.out.write(request.get('entry'))
      else:
          self.response.out.write(template.render(path, {'result': 'Welcome!!'}))



   def main():
      application = webapp.WSGIApplication([('/', MainHandler)],
                                       debug=True)
      wsgiref.handlers.CGIHandler().run(application)

Yet, apparently the function is never being called and #result gets set to ‘Unchanged X’. What am I missing?

NOTE: The callback is NOT being called. I have verified this by placing an alert(“Test”) within the callback function. Any ideas anyone?

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1 Answer

  1. Editorial Team

    First we have the silly mistake:

    <font size="3" face="Trebuchet MS">Speak Your Mind:&nbsp;&nbsp;</font><input type="text"     
size="60" id="entry"/> <img valign="bottom" src='/assets/cognifyup.png' 
onMouseOver="over()" onMouseOut="out()" onMouseDown="out(); evaluate();" 
onMouseUp="over()"><br><br>

    Semicolons are required after the calls to over() and out() (roger that? — sorry couldn’t resist)

    Secondly (the much more subtle problem):

    If we ever need intend to translate the get() into a getJSON() call, (which you might have noted was my original intent from the commented python code that returns a dict), then we need to wrap a str() call around self.request.get('entry'). Hence,

    self.response.out.write({'evalresult': self.request.get('entry')})

    becomes:

    self.response.out.write({'evalresult': str(self.request.get('entry'))})

    As strings from an HTML field translate to unicode text in Python, at the back-end, we apparently need to convert it to a Python string (as getJSON() apparently doesn’t like Python’s representation of a unicode string — any ideas why this this is the case anyone?).

    At any rate, the original problem has been solved. In conclusion: any JSON object with a Python unicode string will not be accepted as a valid JSON object and will fail silently — a nasty gotcha that I can see biting anyone using JQuery with Python on the server-side.

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