view roundup/cgi/TAL/XMLParser.py @ 5630:07abc8d36940

Add etag support to rest interface to prevent multiple users from overwriting other users changes. All GET requests for an object (issue, user, keyword etc.) or a property of an object (e.g the title of an issue) return the etag for the object in the ETag header as well as the @etag field in the returned object. All requests that change existing objects (DELETE, PUT or PATCH) require: 1 A request include an ETag header with the etag value retrieved for the object. 2 A submits a form that includes the field @etag that must have the value retrieved for the object. If an etag is not supplied by one of these methods, or any supplied etag does not match the etag calculated at the time the DELETE, PUT or PATCH request is made, HTTP error 412 (Precondition Failed) is returned and no change is made. At that time the client code should retrieve the object again, reconcile the changes and can try to send a new update. The etag is the md5 hash of the representation (repr()) of the object retrieved from the database.
author John Rouillard <rouilj@ieee.org>
date Fri, 01 Mar 2019 22:57:07 -0500
parents 14a61eabcea8
children
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##############################################################################
#
# Copyright (c) 2001, 2002 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE
#
##############################################################################
# Modifications for Roundup:
# 1. commented out zLOG references
# 2. use roundup.anypy.urllib_
"""
Generic expat-based XML parser base class.
"""

#import zLOG

class XMLParser:

    ordered_attributes = 0

    handler_names = [
        "StartElementHandler",
        "EndElementHandler",
        "ProcessingInstructionHandler",
        "CharacterDataHandler",
        "UnparsedEntityDeclHandler",
        "NotationDeclHandler",
        "StartNamespaceDeclHandler",
        "EndNamespaceDeclHandler",
        "CommentHandler",
        "StartCdataSectionHandler",
        "EndCdataSectionHandler",
        "DefaultHandler",
        "DefaultHandlerExpand",
        "NotStandaloneHandler",
        "ExternalEntityRefHandler",
        "XmlDeclHandler",
        "StartDoctypeDeclHandler",
        "EndDoctypeDeclHandler",
        "ElementDeclHandler",
        "AttlistDeclHandler"
        ]

    def __init__(self, encoding=None):
        self.parser = p = self.createParser()
        # Make sure we don't get fed unicode strings in Python 2 as we
        # can't handle those
        if hasattr(self.parser, 'returns_unicode'):
            self.parser.returns_unicode = False
        if self.ordered_attributes:
            try:
                self.parser.ordered_attributes = self.ordered_attributes
            except AttributeError:
                #zLOG.LOG("TAL.XMLParser", zLOG.INFO, 
                #         "Can't set ordered_attributes")
                self.ordered_attributes = 0
        for name in self.handler_names:
            method = getattr(self, name, None)
            if method is not None:
                try:
                    setattr(p, name, method)
                except AttributeError:
                    #zLOG.LOG("TAL.XMLParser", zLOG.PROBLEM,
                    #         "Can't set expat handler %s" % name)
                    pass

    def createParser(self, encoding=None):
        global XMLParseError
        try:
            from Products.ParsedXML.Expat import pyexpat
            XMLParseError = pyexpat.ExpatError
            return pyexpat.ParserCreate(encoding, ' ')
        except ImportError:
            from xml.parsers import expat
            XMLParseError = expat.ExpatError
            return expat.ParserCreate(encoding, ' ')

    def parseFile(self, filename):
        self.parseStream(open(filename))

    def parseString(self, s):
        self.parser.Parse(s, 1)

    def parseURL(self, url):
        import roundup.anypy.urllib_
        self.parseStream(roundup.anypy.urllib_.urlopen(url))

    def parseStream(self, stream):
        self.parser.ParseFile(stream)

    def parseFragment(self, s, end=0):
        self.parser.Parse(s, end)

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