When I was doing some API testing using Python Mechanize, I struck an internal server error. I tried to find the root cause of the error and I realized that Python’s urllib is doing something weird when encoding strings. It is replacing double quotes with single quotes. I spent more than hour to debug this issue before I realized what was wrong. So I am writing this post to help testers to find the solution for this HTTP error and not spend much time on this.<\/p>\n
Let us see an example of the problem:<\/p>\n
\r\n Import urllib\r\n a = {\"name\":\"tester\",\"company\":{\"id\":\"1\",\"work\":\"QA\"}}\r\n data = urllib.urlencode(a)\r\n print data\r\n<\/pre>\n\nExpected output:<\/b>company=%7B%22work%22%3A+%22QA%22%2C+%22id%22%3A+%221%22%7D&name=tester
\nActual output: <\/b>company=%7B%27work%27%3A+%27QA%27%2C+%27id%27%3A+%271%27%7D&name=tester\n<\/p>\n
Here you can see that , %7B%27 etc are urlencoded parameters. When I check in encoding reference, encoded value of single quote is %27 and double quote is %22.So urllib seems to have replaced the %22 with %27.<\/p>\n
Due to this, the server can\u2019t recognize what I am sending in request and it throws an internal server error. In the interest of time, I simply replaced %27 with %22 in the encoded string.<\/p>\n
\r\nImport urllib\r\na = {\"name\":\"tester\",\"company\":{\"id\":\"1\",\"work\":\"QA\"}}\r\ndata = urllib.urlencode(a)\r\nd1 = data.replace(\u2018%27\u2019,\u2019%22\u2019)\r\nprint d1\r\n<\/pre>\nOutput:<\/b>company=%7B%22work%22%3A+%22QA%22%2C+%22id%22%3A+%221%22%7D&name=tester<\/p>\n
Now you can see that %27 is replaced by %22.<\/p>\n
This is the solution I used to get over the internal server error. But it seems like an ugly hack. If any one of you find a better solution for this problem please let me know.<\/p>\n