python-peps/pep-0222.txt

PEP: 222
Title: Web Library Enhancements
Version: $Revision$
Author: akuchlin@mems-exchange.org (Andrew Kuchling)
Status: Active
Type: Standards Track
Python-Version: 2.1
Created: 18-Aug-2000
Post-History:


Abstract

    This PEP proposes a set of enhancements to the CGI development
    facilities in the Python standard library.  Enhancements might be
    new features, new modules for tasks such as cookie support, or
    removal of obsolete code.

    The intent is to incorporate the proposals emerging from this
    document into Python 2.1, due to be released in the first half of
    2001.


Proposed Changes

    This section lists changes that have been suggested, but about
    which no firm decision has yet been made.  In the final version of
    this PEP, this section should be empty, as all the changes should
    be classified as accepted or rejected.

    fcgi.py : A new module adding support for the FastCGI protocol

    Better debugging support for CGIs from the Unix command line.
    Using Perl's CGI.pm [1], if you run a script from the command
    line, you can enter name=value pairs on standard input.
    cgimodel [2] provides this already.

    Should the existing cgi.py be deprecated and everything moved into
    a 'web' or 'cgi' package?  That would allow removing some
    backward-compatibility cruft.

    cgi.py: keep_blank_values should be on by default. The 'if
    form.has_key()/if form[key].value' nested syntax is unnecessarily
    convoluted.

    cgi.py: We should not be told to create our own subclass just so
    we can handle file uploads. As a practical matter, I have yet to
    find the time to do this right, so I end up reading cgi.py's temp
    file into, at best, another file. Some of our legacy code actually
    reads it into a second temp file, then into a final destination!
    And even if we did, that would mean creating yet another object
    with its __init__ call and associated overhead.

    cgi.py: Delete the references to self.lines for file uploads

    cgi.py: Ideally, the pseudo-dictionary syntax would go away. It
    seems to me that the main reason it is there is to accomodate

        form['field'].file syntax. How about the following:
        form['field'] = '' #no values for key
        form['field'] = 'string' #one value in submission for key
        form['field'] = ['string', 'string', ....] #multiple values
        form['field'] = {'fileName':'remote/path',
                      'binaryValue':'@UIHJBV29489erht...'} #one file
        form['field'] = [{'fileName':'remote/path',
                      'binaryValue':'@UIHJBV29489erht...'},
                     {'fileName':'another/path',
                      'binaryValue':'7r7w7@@@@'}] #multiple files

    cgi.py: I'd prefer "input" or "submission" for the suggested
    FieldStorage() name. The html page into which the data represented
    by FieldStorage() is input is commonly known as a "form", which
    means that when someone refers to "the form" you aren't always
    sure what they are talking about.

    cgi.py: Allow a combination of query data and POST data.
    Currently, if there is POST data, then any query data encoded in
    the URL is ignored.  It would be more convenient if the data from
    those two sources were merged into one dictionary. (XXX but is
    this standard at all?)

    cgi.py: Currently, query data with no `=' are ignored.  Even if
    keep_blank_values is set, queries like `...?value=&...' are
    returned with blank values but queries like `...?value&...' are
    completely lost.  It would be great if such data were made
    available through the FieldStorage interface, either as entries
    with None as values, or in a separate list.

    Utility function: build a query string from a list of 2-tuples

    Higher-level frameworks: add something like Webware or Zope's
    HTTPReqest/HTTPResponse objects.

    An HTML templating module.  (But which one?  There's no clear, or
    even vague, indication of which templating module to enshrine.)

    Dictionary-related utility classes: NoKeyErrors (returns an empty
    string, never a KeyError), PartialStringSubstitution (returns 
    the original key string, never a KeyError)


    
New Modules

    This section lists details about entire new packages or modules
    that should be added to the Python standard library.


Major Changes to Existing Modules

    This section lists details of major changes to existing modules,
    whether in implementation or in interface.  The changes in this
    section therefore carry greater degrees of risk, either in
    introducing bugs or a backward incompatibility.
    

Minor Changes to Existing Modules

    This section lists details of minor changes to existing modules.
    These changes should have relatively small implementations, and
    have little risk of introducing incompatibilities with previous
    versions.


Rejected Changes

    The changes listed in this section were proposed for Python 2.1,
    but were rejected as unsuitable.  For each rejected change, a
    rationale is given describing why the change was deemed
    inappropriate.

    * None yet


Proposed Interface

    XXX open issues: naming convention (studlycaps or underline-separated?);
    no interface for file uploads yet; need to look at all the various 
    packages to see if there's anything else missing; need to look at 
    the cgi.parse*() functions and see if they can be simplified, too.
        
    Parsing functions: carry over most of the parse* functions from cgi.py
    
    # The Response class borrows most of its methods from Zope's
    # HTTPResponse class.
    
    class Response:
        """
        Attributes:
        status: HTTP status code to return
        headers: dictionary of response headers
        body: string containing the body of the HTTP response
        """
        
        def __init__(self, status=200, headers={}, body=""):
            pass
    
        def setStatus(self, status, reason=None):
            "Set the numeric HTTP response code"
            pass
    
        def setHeader(self, name, value):
            "Set an HTTP header"
            pass
    
        def setBody(self, body):
            "Set the body of the response"
            pass
    
        def setCookie(self, name, value,
                      path = XXX,  # What to use as defaults?
                      comment = XXX, 
                      domain = XXX, 
                      max-age = XXX,
                      expires = XXX,
                      secure = XXX
                      ):
            "Set a cookie"
            pass
    
        def expireCookie(self, name):
            "Remove a cookie from the user"
            pass
    
        def redirect(self, url):
            "Redirect the browser to another URL"
            pass
    
        def __str__(self):
            "Convert entire response to a string"
            pass
    
        def dump(self):
            "Return a string representation useful for debugging"
            pass
            
        # XXX methods for specific classes of error:serverError, badRequest, etc.?
    
    
    class Request:
    
        """
        Attributes:
        .headers : dictionary containing HTTP headers
        .cookies : dictionary of cookies
        .form    : data from the form
        .env     : environment dictionary
        """
        
        def __init__(self, environ=os.environ, stdin=sys.stdin,
                     keep_blank_values=0, strict_parsing=0):
            """Initialize the request object, using the provided environment
            and standard input."""
            pass
    
        # Should people just use the dictionaries directly?
        def getHeader(self, name, default=None):
            pass
    
        def getCookie(self, name, default=None):
            pass
    
        def getField(self, name, default=None):
            pass
    
        def getURL(self, n=0, query_string=0):
            """Return the URL of the current request, chopping off 'n' path
            components from the right.  Eg. if the URL is
            "http://foo.com/bar/baz/qux", n=2 would return
            "http://foo.com/bar".  Does not include the query string (if
            any)
            """

        def getBaseURL(self, n=0):
            """Return the base URL of the current request, adding 'n' path
            components to the end to recreate more of the whole URL.  
            
            Eg. if the request URL is
            "http://foo.com/q/bar/baz/qux", n=0 would return
            "http://foo.com/", and n=2 "http://foo.com/q/bar".
            
            Returned URL does not include the query string, if any.
            """
        
        def dump(self):
            "String representation suitable for debugging output"
            pass
    
        # Possibilities?
        def getBrowser(self):
            "Returns Mozilla/IE/Lynx/Opera/whatever"
    
        def isSecure(self):
            "Return true if this is an SSLified request"
            
        
    def wrapper(func, logfile=None):
        """
        Calls the function 'func', passing it the arguments
        (request, response, logfile).  Exceptions are trapped and
        sent to the file 'logfile'.  
        """
        pass

    
Copyright
    
    This document has been placed in the public domain.


References and Footnotes

    [1] CGI.pm:

    [2]   http://www.embl-heidelberg.de/~chenna/pythonpages/



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