TypeError: cannot concatenate 'str' and 'NoneType' objects

[nandhu678]

for district in query:
			self.response.out.write('<tr><td bgcolor="#ffffff" style="font-family:arial;font-size:12px">')
			self.response.out.write(district.Dis_Id)
			self.response.out.write('</td><td bgcolor="#ffffff" style="font-family:arial;font-size:12px">')
			self.response.out.write(district.Dis_Name)
			self.response.out.write('</td><td bgcolor="#ffffff" style="font-family:arial;font-size:12px"><a href="#"onclick="editdistrict(\''+district.Dis_Id+'\');">Edit</a>/<a href="#"onclick="districtdelete(\''+district.Dis_Id+'\');">Delete</a>')

Error:::

Traceback (most recent call last):
  File "D:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 515, in __call__
    handler.post(*groups)
  File "D:\Documents and Settings\purnachandra\Desktop\duplicate\cyberabadpolice.py", line 1102, in post
    self.response.out.write('</td><td bgcolor="#ffffff" style="font-family:arial;font-size:12px"><a href="#"onclick="editdistrict(\''+district.Dis_Id+'\');">Edit</a>/<a href="#"onclick="districtdelete(\''+district.Dis_Id+'\');">Delete</a>')
TypeError: cannot concatenate 'str' and 'NoneType' objects

[Markus]

Please see: http://bytes.com/topic/python/answer...netype-objects

[bvdet]

Apparently the district attribute Dis_Id has no value. The NoneType object is accessed through the built-in name None. Test for a value before attempting the string addition to avoid the error.