form= cgi.FieldStorage()
print form
Prints: FieldStorage(None, None, 'age=10&name=joe').
How do I get the data from that form?
I can't use form[FieldKey], because there is no field key.
form['age'] returns a blank string
I'm using Python 2.7.
This is not an answer. I don't know what's wrong. However, I don't have Python 2 on this computer. I've just run some code on repl.it.
Here's what happens.
It works as it's meant to. Apparently there's something peculiar about your setup. If I think of anything I'll come back.
This happens when FieldStorage parses "plain" POST data, as opposed to a form for example. If the content-type of the HTTP request is application/x-www-form-urlencoded however, it will know what to do.
This is the HTML file that has a single send button, once it is clicked, the name and age data are sent to the proc.py script, after the header is set to what the Python CGI library likes.
<html><body>
<button type="button" onclick="sendData()">Send</button>
<div id="content">No reponse from script yet.</div>
<script>
function sendData() {
var http = new XMLHttpRequest();
http.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById('content').innerHTML = this.responseText;
}
};
http.open('POST', '/cgi-bin/proc.py', true);
http.setRequestHeader('content-type', 'application/x-www-form-urlencoded');
http.send('age=10&name=joe');
}
</script>
</body></html>
And proc.py spits these value back:
#!/usr/bin/env python
import cgi
data = cgi.FieldStorage()
print 'Content-type: text/html\n'
print data['name'].value
print '<br />'
print data['age'].value
Other answers have explained why there was a problem with the request and how to fix it, but I think it might be helpful to better understand the FieldStorage object so you can recover from a bad request.
I was mostly able to duplicate your state using this:
from cgi import FieldStorage
from StringIO import StringIO
f = FieldStorage(
fp=StringIO("age=10&name=joe"),
headers={"content-length": 15, "content-type": "plain/text"},
environ={"REQUEST_METHOD": "POST"}
)
print(f) # FieldStorage(None, None, 'age=10&name=joe')
This will fail as expected:
f["age"] # TypeError: not indexable
f.keys() # TypeError: not indexable
So FieldStorage didn't parse the query string because it didn't know it should, but you can make FieldStorage manually parse it:
f.fp.seek(0) # we reset fp because FieldStorage exhausted it
# if f.fp.seek(0) fails we can also do this:
# f.fp = f.file
f.read_urlencoded()
f["age"] # 10
f.keys() # ["age", "name"]
If you ever need to get the original body from FieldStorage, you can get it from the FieldStorage.file property, the file property gets set when FieldStorage parses what it thinks is a plain body:
f.file.read() # "age=10&name=joe"
Hope this helps other fellow searchers who stumble on this question in the future.
You can try
import cgi
form = cgi.FieldStorage()
print form.getvalue("age")
as described in the more general thread How are POST and GET variables handled in Python?