Hex dump: WSGI Wiki Application

For my WSGI talk at the Sydney Python Meetup I decided that showing a simple "hello world" or echo WSGI application would not hammer home why WSGI is so good. So I decided to create a WSGI wiki app. Also to show what is needed to convert an existing Python CGI script I decided to base it on Ian Bicking's CGI wiki in the Web Framework Shootout. So after about 80 minutes work this is what I came up with and was able to run under isapi_wsgi. It still needs some final touches but it works.


import cgi, os
import cgitb; cgitb.enable()
import Wiki


# There's several different actions that may occur -- we
# may just display the page, we may edit it, save the edits
# that were submitted, or show a preview.  We define each of
# these as a function:

def printPage(page):
    pp = []
    if not page.exists():
        pp.append("This page does not yet exist.  Create it:")
        pp.append(printEdit(page))
    else:
        pp.append(page.html)
        pp.append('<hr noshade>')
        pp.append('<a href="%s?edit=yes">Edit this page</a>'               % page.name)
    return "".join(pp)

def printEdit(page, text=None):
    # The text argument is used in previews -- you want the
    # textarea to be loaded with the same text they submitted.
    pe = []
    if text is None:
        # This isn't a preview, so we get the page's text.
        text = page.text
    pe.append('<h1>Edit %s</h1>' % page.title)
    pe.append('<form action="%s" method="POST">' % page.name)
    pe.append('<textarea name="text" rows=10 cols=50 style="width: 90%%">'           '%s</textarea><br>' % cgi.escape(text))
    pe.append('<input type="submit" name="save" value="Save">')
    pe.append('<input type="submit" name="preview" value="Preview">')
    pe.append('</form>')
    return "".join(pe)

def printSave(page, form):
    ps = []
    page.text = form['text'].value
    ps.append(printPage(page))
    return "".join(ps)

def printPreview(page, form):
    ps = []
    ps.append('<h1>Preview %s</h1>' % page.title)
    ps.append(page.preview(form['text'].value))
    ps.append('<hr noshade>')
    ps.append(printEdit(page, form['text'].value))
    return "".join(ps)

def application(environ, start_response):
    # PATH_INFO contains the portion of the URL that comes after
    # script name.  For all actions, this is the page we are using.
    pagename = environ['PATH_INFO'][1:]
    if len(pagename) == 0:
        pagename = "frontpage"
    page = Wiki.WikiPage(pagename)
    form = cgi.FieldStorage(fp=environ['wsgi.input'],environ=environ)
    start_response('200 OK', [('Content-type','text/html')])
    response = []
    response.append("<html><head><title>%s</title>" % page.title)
    response.append(page.css)
    response.append("</head><body>")
    # Here we use fields to determine what action we should take:
    # edit, save, preview, or display
    if form.has_key('edit'):
        response.append(printEdit(page))
    elif form.has_key('save'):
        response.append(printSave(page, form))
    elif form.has_key('preview'):
        response.append(printPreview(page, form))
    else:
        response.append("<h1>%s</h1>" % page.title)
        response.append(printPage(page))
    response.append("</body></html>")
    return response

Hex dump

Tuesday, March 08, 2005

WSGI Wiki Application

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