Can't include more than one input in webapp2 form
Question
I tried adding an input (text) field to a working example ( https://realpython.com/python-web-applications/ ), and it broke. My Python code is:
import webapp2
def convert_temp(cel_temp):
if cel_temp == "":
return ""
try:
far_temp = float(cel_temp) * 9 / 5 + 32
far_temp = round(far_temp, 3) # round to three decimal places
return str(far_temp)
except ValueError: # user entered non-numeric temperature
return "invalid input"
class MainPage(webapp2.RequestHandler):
def get(self):
cel_temp = self.request.get("cel_temp")
far_temp = convert_temp(cel_temp)
self.response.headers["Content-Type"] = "text/html"
self.response.write("""
<html>
<head><title>Temperature Converter</title></head>
<body>
<form action="/" method="get">
<fieldset>
Celsius temperature: <input type="text" name="cel_temp" value={}><br>
Dummy: <input type="text" name="dummy" value={}>
<input type="submit" value="Convert"><br>
Fahrenheit temperature: {}
</fieldset>
</form>
</body>
</html>""".format(cel_temp, far_temp))
routes = [('/', MainPage)]
my_app = webapp2.WSGIApplication(routes, debug=True)
The new line is the one beginning with "Dummy". The code worked until I put that in, now it throws an internal server error. I'm not getting any clues from looking at HTML doco, so I'm not sure what to try from here.
1 answers
solution1
0 2018-10-13 17:46:59
It's because of the way format works. You need to supply the correct number of arguments at the end, so that you match all the {} with one parameter each. I didn't test it, but this should work, note the empty string as the third argument which should match the third {} :
self.response.write("""
<html>
<head><title>Temperature Converter</title></head>
<body>
<form action="/" method="get">
<fieldset>
Celsius temperature: <input type="text" name="cel_temp" value={}><br>
Dummy: <input type="text" name="dummy" value={}>
<input type="submit" value="Convert"><br>
Fahrenheit temperature: {}
</fieldset>
</form>
</body>
</html>""".format(cel_temp, far_temp, "")
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