- Form Input
- The ServiceRequest object has the following methods:
hasInputs(self, *keys) - tests if a field or fields in the form were filled.getInputs(self, key=None) - which given a key will return a list of all the values associated with this key. If none exits it will return an empty list. When getInputs() is called a cgi.FieldStorage object is returned.getInput(self, key, default=None, index=None) returns the given form field value as a string. If there are multiple values under the same key, it will return the first in the list, unless index is given. If no value is found will return "", unless default is given.
Here is an example: [http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=input - mod_python test]
#!/usr/bin/env python2.1
from pso.service import ServiceHandler, OK
def testInput(serviceRequest):
if serviceRequest.hasInput("submit"):
name = serviceRequest.getInput("name")
options = ",".join(serviceRequest.getInputs("option"))
print """<pre>
name: %s,
options: %s
</pre>""" % (name, options)
else:
print """
<form >
<input name="name">
<input name="option" value="alpha" type="checkbox">alpha
<input name="option" value="omega" type="checkbox">omega
<input type="hidden" name="test" value="input">
<input type="submit" name="submit" value="submit">
</form>
"""
return OK
if __name__ == '__main__':
ServiceHandler().run(testInput)
- server, request header & environment variables
pso emulates the CGI standard, and these variables are available through ServiceRequest.getEnvrion(self, key=None, default=None)that takes a key and either returns a string or default. If no key is given a dictionary is returned of these variables.
#!/usr/bin/env python2.1
from pso.service import ServiceHandler, OK
def testEnviron(serviceRequest):
print "<ul>"
for keyValue in serviceRequest.getEnviron().items():
print "<li>%s: %s" % keyValue
print "</ul>"
return OK
if __name__ == '__main__':
ServiceHandler().run(testEnviron)
- Handling cookies
-
- You get cookies using ServiceRequest.getCookies(self) that returns a dictionary of cookies and their values.
- You get a cookie using ServiceRequest.getCookie(self, key, default=None) which returns the cookie value requested by key otherwise returns default.
- Cookies can be set by using setCookie(self, key, value, **attrs) sets cookie key to value. **attrs is a key word parameter through which you can pass the cookie attributes as defined in RCF2109:
- Comment
- Domain
- Max-Age
- Path
- Secure
- Version
- expires?... Used by netscape et al. This takes a string date such as "Mon, 12 Nov 2002 13:04:56 GMT", as defined in RFC2068 section 3.3.1 [also RCF822 and RCF1123]
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=cookie - mod_python test ]
#!/usr/bin/env python2.1
from pso.service import ServiceHandler, OK
def testCookie(serviceRequest):
if not serviceRequest.getCookie("MyTest"):
print 'setting cookie "MyTest" to "is Tasty" reload to see this cookie'
serviceRequest.setCookie('MyTest','is Tasty')
print"<ul>"
for cookieValue in serviceRequest.getCookies().items():
print "<li>%s: %s" % cookieValue
print "</ul>"
return OK
__name__ == '__main__':
ServiceHandler().run(testCookie)
- File Uploads
pso makes file uploading very easy. It offers the method ServiceRequest.getFile(self, key) that returns a PSOFields object, a subclass of cgi.Field. The return object has all some additional member fields:
filename - the original file's name
file - a file object holding the actual file
tempname - is None until the member method keep()
is called.
The returned fields object has also some new methods:
keep() - For each uploaded file the python standard cgi
library opens a temporary file and immediately deletes (unlinks) it. The
trick (on Unix!) is that the file can still be used, but it can't be opened
by any other process, and it will automatically be deleted when it is closed
or when the current process terminates. keep() gives this temporary a new temporary name. This is especially useful for forms that have a confirmation screen.save(pathName) - renames an uploaded file.
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=upload - mod_python test ]
#!/usr/bin/env python2.1
def testUpload(serviceRequest):
if serviceRequest.hasInputs('file'):
file = serviceRequest.getFile('file')
file.keep()
print """
<form >
Save As: <input name="saveAs" type="text" >
<input name="tempfile" type="hidden" value="%s">
<input name="test" type="hidden" value="upload">
</form> """ % file.tempname
elif serviceRequest.hasInputs('saveAs'):
tempFile = serviceRequest.getInput('tempfile')
saveAs = serviceRequest.getInput( 'saveAs')
import os
print "renaming", tempFile, 'to', '/tmp/'+saveAs
os.rename(tempFile, '/tmp/'+saveAs)
print """
DONE - Thankyou
"""
else:
print """
<form enctype="multipart/form-data" method="POST">
file: <input name="file" type="file" >
<input name="test" type="hidden" value="upload">
<input name="action" type="submit" value="Upload">
</form>"""
return OK
if __name__ == '__main__':
ServiceHandler().run(testUpload)
- Redirection
- Redirection is essential and pso makes this easy. Just call ServiceRequest.redirect(someUrl) and your script will terminate and redirect the client's browser.
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=redirect - mod_python test ]
#!/usr/bin/env python2.1
from pso.service import ServiceHandler,OK
def testRedirect(serviceRequest):
url = serviceRequest.getInput('url')
if not url:
print """
<form >
Redirect to : <input name="url" type="text" size=40">
<input name="test" type="hidden" value="redirect">
</form>"""
else:
serviceRequest.redirect(url)
return OK
if __name__ == '__main__':
ServiceHandler().run(testRedirect)
- Status
- By default
pso always sets the return status to 200. When invoking redirect, pso will set the status code to either 301 or 302. To set the code explicitly you have a choice of invoking:
-
sendStatus(self, status) - this immediately sends the status code and terminates you handler.
-
setStatus(self, status) - this sets the status code but your request handler will continue execution.
For a complete list of these codes you should refer to [ rfc2616 sec6.1.1].
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=status - mod_python test ]
#!/usr/bin/env python2.1
from pso.service import ServiceHandler,OK
def testStatus(serviceRequest):
import time
print time.asctime()
if not serviceRequest.hasInput('status'):
print """
<form>
<input name="status" type="text" size=3" maxsize=3>
<input name="test" type="hidden" value="status">
</form>"""
else:
status = serviceRequest.getInput('status', '204')
serviceRequest.sendStatus(status)
return OK
if __name__ == '__main__':
ServiceHandler().run(testRedirect)
- Target and other http headers
pso sets many headers (status, content_type, cookie), and it is easy to do using :
-
setHeaderOut(self, key, value) - replaces the header entry with the same key.
-
addHeaderOut(self, key, value) - adds the header entry.
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=headerOut - mod_python test ]
#!/usr/bin/env python2.1
from pso.service import ServiceHandler,OK
def testHeaderOut(serviceRequest):
if serviceRequest.hasInputs('url','target'):
serviceRequest.setHeaderOut('Window-target', serviceRequest.getInput('target'))
print "<ul>"
table = serviceRequest.getHeadersOut()
for k in table.keys():
print "<li>",k, table[k]
print "</ul>"
print serviceRequest.getInput('message')
else:
print """
WIndow target seems to only work with netscape, please try and let us know.
<form>
target: <input name="target" type="text" >
message: <input name="message" type="text" size=50 >
<input type="hidden" name="test" value="headerOut">
<input name="action" type="submit" value="write to target">
</form>"""
__name__ == '__main__':
ServiceHandler().run(testHeaderOut)
- sys.stdout
- When using psosys.stdout is buffered until the termination of the
request handler or the invocation of ServiceRequest.send_http_header(
self, content_type='text/html'). This system allows you to use print
without worrying about when you set the headers, cookies or when you what
to redirect. Buffering can damage a performance on very large return screens,
yet it can simplify the program logic, and in most cases web services try
to fit their return results on one screen. When you want top stop buffering
just send the headers, using the method send_http_header. If you
want write directly to the sys.stdout before sending the headers
you can use:
requestService.write(someString)
- sys.stderr and logging
- By default
the output to sys.stderr is posted to the httpd log, but this can be easily
changed using the following httpd directive:
| CGI | mod_python |
|---|
SetEnv PSOLog=/path/to/some/Log |
PythonOption PSOLog=/path/to/some/Log |
pso.ServiceRequest also has a member function log(self, *listToPost)
that will post a line to the log starting with a timestamp then followed
by the parameters in listToPost.
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=error - mod_python test ]
#!/usr/bin/env python2.1
from pso.service import ServiceHandler, OK
class ErrorToBeLogged(Exception): pass
class ErrorForTraceBack(Exception): pass
def testError(serviceRequest):
print "<pre>"
try:
raise ErrorToBeLogged()
except ErrorToBeLogged, e:
serviceRequest.log('just caught this error:', e.__class__, "<br>")
try:
raise ErrorForTraceBack()
except:
import traceback
traceback.print_exc()
import os
print os.popen("tail -50 /tmp/psotestlog").read()
return OK
__name__ == '__main__':
ServiceHandler().run(testError)
- building urls
- Any web request handler will be building many urls. This is tedious and error prone so
pso.ServiceRequest offers
a set of member methods to make things easy for you:
-
baseUri(self) - TODO.
-
buildUri(self, parts, clean, **kws) - TODO.
-
serviceUri(self, clean=1, **kws) - TODO.
-
uriParts(self) -TODO.
- Session Handling
- By default every
pso request has a session object. getSession() retrieves it. It is a mutable dictionary whose contents is saved between invocations of the request handler. The document Easy mod_python session handling using pso.session or Easy CGI session handling using pso.session describe session handling with pso in greater detail.
Here is an example:
[http://www.0x01.com/~thanos/pso/tests/guide/testGuide.cgi?test=session - mod_python test ]
#!/usr/bin python2.1
from pso.service import ServiceHandler, OK
def testSession(serviceRequest):
session = serviceRequest.pso().session
try:
session['reloads'] +=1
except:
session['reloads'] =0
print "<br>hello World! ~ Your number of reloads: %(reloads)d ~ Try Reload !" % session
print "<br>session: %s" % session.__dict__
return OK
if __name__ == '__main__':
ServiceHandler().run(testSession)