Merge github.com:web2py/web2py

gluon/cache.py

@@ -11,7 +11,7 @@ Basic caching classes and methods
 
 - Cache - The generic caching object interfacing with the others
 - CacheInRam - providing caching in ram
-- CacheInDisk - provides caches on disk
+- CacheOnDisk - provides caches on disk
 
 Memcache is also available via a different module (see gluon.contrib.memcache)
 
@@ -130,22 +130,27 @@ class CacheInRam(CacheAbstract):
     meta_storage = {}
 
     def __init__(self, request=None):
-        self.locker.acquire()
+        self.initialized = False
         self.request = request
+
+    def initialize(self):
+        if self.initialized: return
+        else: self.initialized = True
+        self.locker.acquire()
+        request = self.request
         if request:
             app = request.application
         else:
             app = ''
         if not app in self.meta_storage:
-            self.storage = self.meta_storage[app] = {CacheAbstract.cache_stats_name: {
-                'hit_total': 0,
-                'misses': 0,
-            }}
+            self.storage = self.meta_storage[app] = {
+                CacheAbstract.cache_stats_name: {'hit_total': 0, 'misses': 0}}
         else:
             self.storage = self.meta_storage[app]
         self.locker.release()
 
     def clear(self, regex=None):
+        self.initialize()
         self.locker.acquire()
         storage = self.storage
         if regex is None:
@@ -154,10 +159,7 @@ class CacheInRam(CacheAbstract):
             self._clear(storage, regex)
 
         if not CacheAbstract.cache_stats_name in storage.keys():
-            storage[CacheAbstract.cache_stats_name] = {
-                'hit_total': 0,
-                'misses': 0,
-            }
+            storage[CacheAbstract.cache_stats_name] = {'hit_total': 0,'misses': 0}
 
         self.locker.release()
 
@@ -172,6 +174,7 @@ class CacheInRam(CacheAbstract):
         3) would work unless we deepcopy no storage and retrival which would make things slow.
         Anyway. You can deepcopy explicitly in the function generating the value to be cached.
         """
+        self.initialize()
 
         dt = time_expire
         now = time.time()
@@ -200,6 +203,7 @@ class CacheInRam(CacheAbstract):
         return value
 
     def increment(self, key, value=1):
+        self.initialize()
         self.locker.acquire()
         try:
             if key in self.storage:
@@ -226,58 +230,65 @@ class CacheOnDisk(CacheAbstract):
     Values stored in disk cache must be pickable.
     """
 
-    speedup_checks = set()
+    def _close_shelve_and_unlock(self):
+        try:
+            if self.storage:
+                self.storage.close()
+        finally:
+            if self.locker and self.locked:
+                portalocker.unlock(self.locker)
+                self.locker.close()
+                self.locked = False
 
-    def _open_shelf_with_lock(self):
+    def _open_shelve_and_lock(self):
         """Open and return a shelf object, obtaining an exclusive lock
         on self.locker first. Replaces the close method of the
         returned shelf instance with one that releases the lock upon
         closing."""
-        def _close(self):
-            try:
-                shelve.Shelf.close(self)
-            finally:
-                portalocker.unlock(self.locker)
-                self.locker.close()
-
-        storage, locker, locker_locked = None, None, False
+        
+        storage = None
+        locker = None
+        locked = False
         try:
-            locker = open(self.locker_name, 'a')
+            locker = locker = open(self.locker_name, 'a')
             portalocker.lock(locker, portalocker.LOCK_EX)
-            locker_locked = True
-            storage = shelve.open(self.shelve_name)
-            storage.close = _close.__get__(storage, shelve.Shelf)
-            storage.locker = locker
-        except Exception:
-            logger.error('corrupted cache file %s, will try to delete and recreate it!' % (self.shelve_name))
+            locked = True
+            try:
+                storage = shelve.open(self.shelve_name)
+            except:
+                logger.error('corrupted cache file %s, will try rebuild it' \
+                                 % (self.shelve_name))
+                storage = None
+            if not storage and os.path.exists(self.shelve_name):
+                os.unlink(self.shelve_name)
+                storage = shelve.open(self.shelve_name)
+            if not CacheAbstract.cache_stats_name in storage.keys():
+                storage[CacheAbstract.cache_stats_name] = {'hit_total':0, 'misses': 0}
+            storage.sync()
+        except Exception, e:
             if storage:
                 storage.close()
                 storage = None
-
-            try:
-                os.unlink(self.shelve_name)
-                storage = shelve.open(self.shelve_name)
-                storage.close = _close.__get__(storage, shelve.Shelf)
-                storage.locker = locker
-                if not CacheAbstract.cache_stats_name in storage.keys():
-                    storage[CacheAbstract.cache_stats_name] = {
-                        'hit_total': 0,
-                        'misses': 0,
-                    }
-                storage.sync()
-            except (IOError, OSError):
-                logger.warn('unable to delete and recreate cache file %s' % self.shelve_name)
-                if storage:
-                        storage.close()
-                        storage = None
-                if locker_locked:
-                    portalocker.unlock(locker)
-                if locker:
-                    locker.close()
+            if locked:
+                portalocker.unlock(locker)
+                locker.close()
+            locked = False
+            raise RuntimeError, 'unable to create/re-create cache file %s' % self.shelve_name
+        self.locker = locker
+        self.locked = locked
+        self.storage = storage
         return storage
 
-    def __init__(self, request, folder=None):
+    def __init__(self, request=None, folder=None):
+        self.initialized = False
         self.request = request
+        self.folder = folder
+ 
+    def initialize(self):
+        if self.initialized: return
+        else: self.initialized = True
+        folder = self.folder
+        request = self.request
 
         # Lets test if the cache folder exists, if not
         # we are going to create it
@@ -291,93 +302,54 @@ class CacheOnDisk(CacheAbstract):
         self.locker_name = os.path.join(folder,'cache.lock')
         self.shelve_name = os.path.join(folder,'cache.shelve')
 
-        speedup_key = (folder,CacheAbstract.cache_stats_name)
-        if not speedup_key in self.speedup_checks or \
-                not os.path.exists(self.shelve_name):
-            try:
-                storage = self._open_shelf_with_lock()
-                try:
-                    if not CacheAbstract.cache_stats_name in storage:
-                        storage[CacheAbstract.cache_stats_name] = {
-                            'hit_total': 0,
-                            'misses': 0,
-                        }
-                        storage.sync()
-                finally:
-                    storage.close()
-                self.speedup_checks.add(speedup_key)
-            except ImportError:
-                pass # no module _bsddb, ignoring exception now so it makes a ticket only if used
-
     def clear(self, regex=None):
-        storage = self._open_shelf_with_lock()
+        self.initialize()
+        storage = self._open_shelve_and_lock()
         try:
             if regex is None:
                 storage.clear()
             else:
                 self._clear(storage, regex)
-            if not CacheAbstract.cache_stats_name in storage.keys():
-                storage[CacheAbstract.cache_stats_name] = {
-                    'hit_total': 0,
-                    'misses': 0,
-                }
             storage.sync()
         finally:
-            storage.close()
+            self._close_shelve_and_unlock()
 
     def __call__(self, key, f,
                 time_expire = DEFAULT_TIME_EXPIRE):
+        self.initialize()
         dt = time_expire
-
-        storage = self._open_shelf_with_lock()
+        storage = self._open_shelve_and_lock()
         try:
             item = storage.get(key, None)
+            storage[CacheAbstract.cache_stats_name]['hit_total'] += 1
             if item and f is None:
                 del storage[key]
-
-            storage[CacheAbstract.cache_stats_name] = {
-                'hit_total': storage[CacheAbstract.cache_stats_name]['hit_total'] + 1,
-                'misses': storage[CacheAbstract.cache_stats_name]['misses']
-            }
-
-            storage.sync()
+                storage.sync()
+            now = time.time()
+            if f is None:
+                value = None
+            elif item and (dt is None or item[0] > now - dt):
+                value = item[1]
+            else:
+                value = f()
+                storage[key] = (now, value)
+                storage[CacheAbstract.cache_stats_name]['misses']+=1
+                storage.sync()
         finally:
-            if storage:
-                storage.close()
-
-        now = time.time()
-        if f is None:
-            return None
-        if item and (dt is None or item[0] > now - dt):
-            return item[1]
-        value = f()
-
-        storage = self._open_shelf_with_lock()
-        try:
-            storage[key] = (now, value)
-
-            storage[CacheAbstract.cache_stats_name] = {
-                'hit_total': storage[CacheAbstract.cache_stats_name]['hit_total'],
-                'misses': storage[CacheAbstract.cache_stats_name]['misses'] + 1
-            }
-
-            storage.sync()
-        finally:
-            if storage:
-                storage.close()
+            self._close_shelve_and_unlock()
 
         return value
 
     def increment(self, key, value=1):
-        storage = self._open_shelf_with_lock()
+        self.initialize()
+        storage = self._open_shelve_and_lock()
         try:
             if key in storage:
                 value = storage[key][1] + value
             storage[key] = (time.time(), value)
             storage.sync()
         finally:
-            if storage:
-                storage.close()
+            self._close_shelve_and_unlock()
         return value
 
 class CacheAction(object):
@@ -423,10 +395,9 @@ class Cache(object):
             the global request object
         """
         # GAE will have a special caching
-
         if have_settings and settings.global_settings.web2py_runtime_gae:
             from contrib.gae_memcache import MemcacheClient
-            self.ram=self.disk=MemcacheClient(request)
+            self.ram = self.disk = MemcacheClient(request)
         else:
             # Otherwise use ram (and try also disk)
             self.ram = CacheInRam(request)
@@ -489,7 +460,6 @@ class Cache(object):
             cache_model(prefix + key, f, time_expire)
 
 
-
 def lazy_cache(key=None,time_expire=None,cache_model='ram'):
     """
     can be used to cache any function including in modules,

gluon/compileapp.py

@@ -387,6 +387,7 @@ def build_environment(request, response, session, store_current=True):
 
     t = environment['T'] = translator(request)
     c = environment['cache'] = Cache(request)
+
     if store_current:
         current.globalenv = environment
         current.request = request

gluon/contrib/gae_memcache.py

@@ -44,7 +44,7 @@ class MemcacheClient(Client):
         obj = self.get(key)
         if obj:
             value = obj[1] + value
-        self.set((time.time(), value))
+        self.set(key, (time.time(), value))        
         return value
 
     def clear(self, key = None):

gluon/contrib/redis_session.py

@@ -0,0 +1,198 @@
+"""
+Developed by niphlod@gmail.com
+"""
+
+import redis
+from redis.exceptions import ConnectionError
+from gluon import current
+from gluon.storage import Storage
+import cPickle as pickle
+import time
+import re
+import logging
+import thread
+
+logger = logging.getLogger("web2py.session.redis")
+
+locker = thread.allocate_lock()
+
+def RedisSession(*args, **vars):
+    """
+    Usage example: put in models
+
+    sessiondb = RedisSession('localhost:6379',db=0, debug=True)
+    session.connect(request, response, db = sessiondb)
+
+    Simple slip-in storage for session
+    """
+
+    locker.acquire()
+    try:
+        if not hasattr(RedisSession, 'redis_instance'):
+            RedisSession.redis_instance = RedisClient(*args, **vars)
+    finally:
+        locker.release()
+    return RedisSession.redis_instance
+
+
+class RedisClient(object):
+
+    meta_storage = {}
+    MAX_RETRIES = 5
+    RETRIES = 0
+
+    def __init__(self, server='localhost:6379', db=None, debug=False, session_expiry=False):
+        """session_expiry can be an integer, in seconds, to set the default expiration
+           of sessions. The corresponding record will be deleted from the redis instance,
+           and there's virtually no need to run sessions2trash.py
+        """
+        self.server = server
+        self.db = db or 0
+        host,port = (self.server.split(':')+['6379'])[:2]
+        port = int(port)
+        self.debug = debug
+        if current and current.request:
+            self.app = current.request.application
+        else:
+            self.app = ''
+        self.r_server = redis.Redis(host=host, port=port, db=self.db)
+        self.tablename = None
+        self.session_expiry = session_expiry
+
+    def get(self, what, default):
+        return self.tablename
+
+    def Field(self, fieldname, type='string', length=None, default=None,
+              required=False,requires=None):
+        return None
+
+    def define_table(self,tablename,*fields,**args):
+        if not self.tablename:
+            self.tablename = MockTable(self, self.r_server, tablename, self.session_expiry)
+        return self.tablename
+
+    def __getitem__(self, key):
+        return self.tablename
+
+    def __call__(self, where=''):
+        q = self.tablename.query
+        return q
+
+    def commit(self):
+        #this is only called by session2trash.py
+        pass
+
+class MockTable(object):
+
+    def __init__(self, db, r_server, tablename, session_expiry):
+        self.db = db
+        self.r_server = r_server
+        self.tablename = tablename
+        #set the namespace for sessions of this app
+        self.keyprefix = 'w2p:sess:%s' % tablename.replace('web2py_session_', '')
+        #fast auto-increment id (needed for session handling)
+        self.serial = "%s:serial" % self.keyprefix
+        #index of all the session keys of this app
+        self.id_idx = "%s:id_idx" % self.keyprefix
+        #remember the session_expiry setting
+        self.session_expiry = session_expiry
+
+    def getserial(self):
+        #return an auto-increment id
+        return "%s" % self.r_server.incr(self.serial, 1)
+
+    def __getattr__(self, key):
+        if key == 'id':
+            #return a fake query. We need to query it just by id for normal operations
+            self.query = MockQuery(field='id', db=self.r_server, prefix=self.keyprefix, session_expiry=self.session_expiry)
+            return self.query
+        elif key == '_db':
+            #needed because of the calls in sessions2trash.py and globals.py
+            return self.db
+
+    def insert(self, **kwargs):
+        #usually kwargs would be a Storage with several keys:
+        #'locked', 'client_ip','created_datetime','modified_datetime'
+        #'unique_key', 'session_data'
+        #retrieve a new key
+        newid = self.getserial()
+        key = "%s:%s" % (self.keyprefix, newid)
+        #add it to the index
+        self.r_server.sadd(self.id_idx, key)
+        #set a hash key with the Storage
+        self.r_server.hmset(key, kwargs)
+        if self.session_expiry:
+            self.r_server.expire(key, self.session_expiry)
+        return newid
+
+class MockQuery(object):
+    """a fake Query object that supports querying by id
+       and listing all keys. No other operation is supported 
+    """
+    def __init__(self, field=None, db=None, prefix=None, session_expiry=False):
+        self.field = field
+        self.value = None
+        self.db = db
+        self.keyprefix = prefix
+        self.op = None
+        self.session_expiry = session_expiry
+
+    def __eq__(self, value, op='eq'):
+        self.value = value
+        self.op = op
+
+    def __gt__(self, value, op='ge'):
+        self.value = value
+        self.op = op
+
+    def select(self):
+        if self.op == 'eq' and self.field == 'id' and self.value:
+            #means that someone wants to retrieve the key self.value
+            rtn = self.db.hgetall("%s:%s" % (self.keyprefix, self.value))
+            if rtn == dict():
+                #return an empty resultset for non existing key
+                return []
+            else:
+                return [Storage(rtn)]
+        elif self.op == 'ge' and self.field == 'id' and self.value == 0:
+            #means that someone wants the complete list
+            rtn = []
+            id_idx = "%s:id_idx" % self.keyprefix
+            #find all session keys of this app
+            allkeys = self.db.smembers(id_idx)
+            for sess in allkeys:
+                val = self.db.hgetall(sess)
+                if val == dict():
+                    if self.session_expiry:
+                        #clean up the idx, because the key expired
+                        self.db.srem(id_idx, sess)
+                        continue
+                    else:
+                        continue
+                val = Storage(val)
+                #add a delete_record method (necessary for sessions2trash.py)
+                val.delete_record = RecordDeleter(self.db, sess, self.keyprefix)
+                rtn.append(val)
+            return rtn
+        else:
+            raise Exception("Operation not supported")
+
+    def update(self, **kwargs):
+        #means that the session has been found and needs an update
+        if self.op == 'eq' and self.field == 'id' and self.value:
+            return self.db.hmset("%s:%s" % (self.keyprefix, self.value), kwargs)
+
+class RecordDeleter(object):
+    """Dumb record deleter to support sessions2trash.py"""
+    
+    def __init__(self, db, key, keyprefix):
+        self.db, self.key, self.keyprefix = db, key, keyprefix
+        
+    def __call__(self):
+        id_idx = "%s:id_idx" % self.keyprefix
+        #remove from the index
+        self.db.srem(id_idx, self.key)
+        #remove the key itself
+        self.db.delete(self.key)
+        
+    

gluon/dal.py

@@ -3981,8 +3981,8 @@ class DatabaseStoredFile:
         self.data += data
 
     def close_connection(self):
-        self.db.executesql("DELETE FROM web2py_filesystem WHERE path='%s'" \
-                               % self.filename)
+        self.db.executesql(
+            "DELETE FROM web2py_filesystem WHERE path='%s'" % self.filename)
         query = "INSERT INTO web2py_filesystem(path,content) VALUES ('%s','%s')"\
             % (self.filename, self.data.replace("'","''"))
         self.db.executesql(query)
@@ -4007,7 +4007,7 @@ class UseDatabaseStoredFile:
         return DatabaseStoredFile(self.db,filename,mode)
 
     def file_close(self, fileobj):
-        fileobj.close()
+        fileobj.close_connection()
 
     def file_delete(self,filename):
         query = "DELETE FROM web2py_filesystem WHERE path='%s'" % filename

gluon/globals.py

@@ -417,7 +417,7 @@ class Response(Storage):
         return handler(request, self, methods)
 
     def toolbar(self):
-        from html import DIV, SCRIPT, BEAUTIFY, TAG, URL
+        from html import DIV, SCRIPT, BEAUTIFY, TAG, URL, A
         BUTTON = TAG.button
         admin = URL("admin","default","design",
                     args=current.request.application)
@@ -438,19 +438,21 @@ class Response(Storage):
             dbstats = [] # if no db or on GAE
             dbtables = {}
         u = web2py_uuid()
+        backtotop = A('Back to top', _href="#totop-%s" % u)
         return DIV(
             BUTTON('design',_onclick="document.location='%s'" % admin),
             BUTTON('request',_onclick="jQuery('#request-%s').slideToggle()"%u),
-            DIV(BEAUTIFY(current.request),_class="hidden",_id="request-%s"%u),
-            BUTTON('session',_onclick="jQuery('#session-%s').slideToggle()"%u),
-            DIV(BEAUTIFY(current.session),_class="hidden",_id="session-%s"%u),
             BUTTON('response',_onclick="jQuery('#response-%s').slideToggle()"%u),
-            DIV(BEAUTIFY(current.response),_class="hidden",_id="response-%s"%u),
+            BUTTON('session',_onclick="jQuery('#session-%s').slideToggle()"%u),
             BUTTON('db tables',_onclick="jQuery('#db-tables-%s').slideToggle()"%u),
-            DIV(BEAUTIFY(dbtables),_class="hidden",_id="db-tables-%s"%u),
             BUTTON('db stats',_onclick="jQuery('#db-stats-%s').slideToggle()"%u),
-            DIV(BEAUTIFY(dbstats),_class="hidden",_id="db-stats-%s"%u),
+            DIV(BEAUTIFY(current.request), backtotop,_class="hidden",_id="request-%s"%u),
+            DIV(BEAUTIFY(current.session), backtotop, _class="hidden",_id="session-%s"%u),
+            DIV(BEAUTIFY(current.response), backtotop, _class="hidden",_id="response-%s"%u),
+            DIV(BEAUTIFY(dbtables), backtotop, _class="hidden",_id="db-tables-%s"%u),
+            DIV(BEAUTIFY(dbstats), backtotop, _class="hidden",_id="db-stats-%s"%u),
             SCRIPT("jQuery('.hidden').hide()")
+            ,_id="totop-%s" % u
             )
 
 class Session(Storage):
@@ -482,7 +484,7 @@ class Session(Storage):
         if not masterapp:
             masterapp = request.application
         response.session_id_name = 'session_id_%s' % masterapp.lower()
-
+        
         # Load session data from cookie
         cookies = request.cookies
             

gluon/main.py

@@ -88,7 +88,7 @@ from contenttype import contenttype
 from dal import BaseAdapter
 from settings import global_settings
 from validators import CRYPT
-from cache import Cache
+from cache import CacheInRam
 from html import URL, xmlescape
 from utils import is_valid_ip_address
 from rewrite import load, url_in, thread as rwthread, \
@@ -148,7 +148,7 @@ def get_client(env):
 def copystream_progress(request, chunk_size= 10**5):
     """
     copies request.env.wsgi_input into request.body
-    and stores progress upload status in cache.ram
+    and stores progress upload status in cache_ram
     X-Progress-ID:length and X-Progress-ID:uploaded
     """
     env = request.env
@@ -164,16 +164,16 @@ def copystream_progress(request, chunk_size= 10**5):
         copystream(source, dest, size, chunk_size)
         return dest
     cache_key = 'X-Progress-ID:'+request.vars['X-Progress-ID']
-    cache = Cache(request)
-    cache.ram(cache_key+':length', lambda: size, 0)
-    cache.ram(cache_key+':uploaded', lambda: 0, 0)
+    cache_ram = CacheInRam(request)  # same as cache.ram because meta_storage
+    cache_ram(cache_key+':length', lambda: size, 0)
+    cache_ram(cache_key+':uploaded', lambda: 0, 0)
     while size > 0:
         if size < chunk_size:
             data = source.read(size)
-            cache.ram.increment(cache_key+':uploaded', size)
+            cache_ram.increment(cache_key+':uploaded', size)
         else:
             data = source.read(chunk_size)
-            cache.ram.increment(cache_key+':uploaded', chunk_size)
+            cache_ram.increment(cache_key+':uploaded', chunk_size)
         length = len(data)
         if length > size:
             (data, length) = (data[:size], size)
@@ -184,8 +184,8 @@ def copystream_progress(request, chunk_size= 10**5):
         if length < chunk_size:
             break
     dest.seek(0)
-    cache.ram(cache_key+':length', None)
-    cache.ram(cache_key+':uploaded', None)
+    cache_ram(cache_key+':length', None)
+    cache_ram(cache_key+':uploaded', None)
     return dest
 
 
@@ -425,19 +425,23 @@ def wsgibase(environ, responder):
                 # ##################################################
                 app = request.application ## must go after url_in!
 
-                http_host = env.http_host.split(':',1)[0]
-                local_hosts = [http_host,'::1','127.0.0.1',
-                               '::ffff:127.0.0.1']
-                if not global_settings.web2py_runtime_gae:
-                    try:
-                        local_hosts.append(socket.gethostname())
-                    except TypeError:
-                        pass
-                    try:
-                        local_hosts.append(
-                            socket.gethostbyname(http_host))
-                    except (socket.gaierror,TypeError):
-                        pass
+                if not global_settings.local_hosts:
+                    local_hosts = ['127.0.0.1','::ffff:127.0.0.1']
+                    if not global_settings.web2py_runtime_gae:
+                        try:
+                            local_hosts.append(socket.gethostname())
+                        except TypeError:
+                            pass
+                        try:
+                            if env.server_name:
+                                local_hosts += [
+                                    env.server_name,
+                                    socket.gethostbyname(env.server_name)]
+                        except (socket.gaierror,TypeError):
+                            pass
+                    global_settings.local_hosts = local_hosts
+                else:
+                    local_hosts = global_settings.local_hosts
                 client = get_client(env)
                 x_req_with = str(env.http_x_requested_with).lower()
                 

gluon/rocket.py

@@ -1466,7 +1466,7 @@ class Worker(Thread):
                     except UnicodeDecodeError:
                         self.err_log.warning('Invalid request header: '+repr(l))
 
-                if l.strip() == '':
+                if l.strip().replace('\0','') == '':
                     break
                 elif l[0] in ' \t' and lname:
                     # Some headers take more than one line

gluon/settings.py

@@ -6,6 +6,7 @@ License: LGPLv3 (http://www.gnu.org/licenses/lgpl.html)
 
 import os
 import sys
+import socket
 import platform
 from storage import Storage
 
@@ -37,4 +38,3 @@ global_settings.is_jython = \
     str(sys.copyright).find('Jython') > 0
 
 
-

gluon/sqlhtml.py

@@ -1059,7 +1059,7 @@ class SQLFORM(FORM):
 
             xfields.append((row_id,label,inp,comment))
             self.custom.dspval[fieldname] = dspval or nbsp
-            self.custom.inpval[fieldname] = inpval or ''
+            self.custom.inpval[fieldname] = inpval if not inpval is None else ''
             self.custom.widget[fieldname] = inp
 
         # if a record is provided and found, as is linkto

gluon/tools.py

@@ -4576,6 +4576,7 @@ class Wiki(object):
         self.env['component'] = Wiki.component
         if render == 'markmin': render=self.markmin_render
         elif render == 'html': render=self.html_render
+        self.render = render
         self.auth = auth
         if self.auth.user:
             self.force_prefix = force_prefix % self.auth.user
@@ -4702,6 +4703,8 @@ class Wiki(object):
                                )
         elif zero=='_cloud':
             return self.cloud()
+        elif zero == '_preview':
+            return self.preview(self.render)
 
     def first_paragraph(self,page):
         if not self.can_read(page):
@@ -4782,7 +4785,29 @@ class Wiki(object):
         elif form.accepted:
             current.session.flash = 'page created'
             redirect(URL(args=slug))
-        return dict(content=form)
+        script = """
+        $(function() {
+            if (!$('#wiki_page_body').length) return;
+            var pagecontent = $('#wiki_page_body');
+            var prevbutton = $('<button class="btn nopreview">Preview</button>');
+            var preview = $('<div id="preview"></div>').hide();
+            var table = $('form');
+            prevbutton.insertBefore(table);
+            prevbutton.on('click', function(e) {
+                e.preventDefault();
+                if (prevbutton.hasClass('nopreview')) {
+                    prevbutton.addClass('preview').removeClass('nopreview').html('Edit Source');
+                    preview.insertBefore(table);
+                    web2py_ajax_page('post', '%(url)s', {body : $('#wiki_page_body').val()}, 'preview');
+                    table.fadeOut('medium', function() {preview.fadeIn()});
+                } else {
+                    prevbutton.addClass('nopreview').removeClass('preview').html('Preview');
+                    preview.fadeOut('medium', function() {table.fadeIn()});
+                }
+            })
+        })
+        """ % dict(url=URL(args=('_preview')))
+        return dict(content=TAG[''](form, SCRIPT(script)))
 
     def editmedia(self,slug):
         auth = self.auth
@@ -4977,6 +5002,9 @@ class Wiki(object):
                                      vars=dict(q=item.wiki_tag.name))))
             items.append(' ')
         return dict(content = DIV(_class='w2p_cloud',*items))
+    def preview(self, render):
+        request = current.request
+        return render(request.post_vars)
 
 if __name__ == '__main__':
     import doctest