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web.py 0.2 API documentation




Guido van Rossum sez: don’t use this function.
render(template, terms=None, asTemplate=False, base=None, isString=False):
Renders a template, caching where it can.

template is the name of a file containing the a template in the templates/ folder, unless isString, in which case it’s the template itself.

terms is a dictionary used to fill the template. If it’s None, then the caller’s local variables are used instead, plus context, if it’s not already set, is set to context.

If asTemplate is False, it outputs the template directly. Otherwise, it returns the template object.

If the template is a potential base template (that is, something other templates) can extend, then base should be a string with the name of the template. The template will be cached and made available for future calls to render.

Requires Cheetah.

class WebSafe(Filter)


Supports Firebird, MySQL, PostgreSQL, and SQLite.

class UnknownParamstyle(Exception)
raised for unsupported db paramstyles

(currently supported: qmark, numeric, format, pyformat)

Returns the appropriate string to be used to interpolate a value with the current web.ctx.db_module or simply %s if there isn’t one.
>>> aparam()
reparam(string_, dictionary)
Takes a string and a dictionary and interpolates the string using values from the dictionary. Returns an SQLQuery for the result.
>>> reparam("s = $s", dict(s=True))
<sql: "s = 't'">
converts obj to its proper SQL version
>>> sqlify(None)
>>> sqlify(True)
>>> sqlify(3)
class SQLQuery
You can pass this sort of thing as a clause in any db function. Otherwise, you can pass a dictionary to the keyword argument vars and the function will call reparam for you.
class SQLLiteral
Protects a string from sqlquote.
>>> insert('foo', time=SQLLiteral('NOW()'), _test=True)
<sql: 'INSERT INTO foo (time) VALUES (NOW())'>
Ensures a is quoted properly for use in a SQL query.
>>> 'WHERE x = ' + sqlquote(True) + ' AND y = ' + sqlquote(3)
<sql: "WHERE x = 't' AND y = 3">
class UnknownDB(Exception)
raised for unsupported dbms
connect(dbn, **keywords)
Connects to the specified database.

dbn currently must be “postgres”, “mysql”, or “sqlite”.

If DBUtils is installed, connection pooling will be used.

class TransactionError(Exception): pass class transaction:
A context that can be used in conjunction with “with” statements to implement SQL transactions. Starts a transaction on enter, rolls it back if there’s an error; otherwise it commits it at the end.
Start a transaction.
Commits a transaction.
Rolls back a transaction.
query(sql_query, vars=None, processed=False, _test=False)
Execute SQL query sql_query using dictionary vars to interpolate it. If processed=True, vars is a reparam-style list to use instead of interpolating.
>>> query("SELECT * FROM foo", _test=True)
<sql: 'SELECT * FROM foo'>
>>> query("SELECT * FROM foo WHERE x = $x", vars=dict(x='f'), _test=True)
<sql: "SELECT * FROM foo WHERE x = 'f'">
>>> query("SELECT * FROM foo WHERE x = " + sqlquote('f'), _test=True)
<sql: "SELECT * FROM foo WHERE x = 'f'">
Converts the arguments for use in something like a WHERE clause.
>>> sqllist(['a', 'b'])
'a, b'
>>> sqllist('foo')
>>> sqllist(u'foo')
sqlors(left, lst)
left is a SQL clause like tablename.arg = ` and lst is a list of values. Returns a reparam-style pair featuring the SQL that ORs together the clause for each item in the lst.
>>> sqlors('foo = ', [])
<sql: '2+2=5'>
>>> sqlors('foo = ', [1])
<sql: 'foo = 1'>
>>> sqlors('foo = ', 1)
<sql: 'foo = 1'>
>>> sqlors('foo = ', [1,2,3])
<sql: '(foo = 1 OR foo = 2 OR foo = 3)'>
sqlwhere(dictionary, grouping=' AND ')
Converts a dictionary to an SQL WHERE clause SQLQuery.
>>> sqlwhere({'cust_id': 2, 'order_id':3})
<sql: 'order_id = 3 AND cust_id = 2'>
>>> sqlwhere({'cust_id': 2, 'order_id':3}, grouping=', ')
<sql: 'order_id = 3, cust_id = 2'>
select(tables, vars=None, what='*', where=None, order=None, group=None, limit=None, offset=None, _test=False):
Selects what from tables with clauses where, order, group, limit, and offset. Uses vars to interpolate. Otherwise, each clause can be a SQLQuery.
>>> select('foo', _test=True)
<sql: 'SELECT * FROM foo'>
>>> select(['foo', 'bar'], where="foo.bar_id = bar.id", limit=5, _test=True)
<sql: 'SELECT * FROM foo, bar WHERE foo.bar_id = bar.id LIMIT 5'>
insert(tablename, seqname=None, _test=False, **values)
Inserts values into tablename. Returns current sequence ID. Set seqname to the ID if it’s not the default, or to False if there isn’t one.
>>> insert('foo', joe='bob', a=2, _test=True)
<sql: "INSERT INTO foo (a, joe) VALUES (2, 'bob')">
update(tables, where, vars=None, _test=False, **values)
Update tables with clause where (interpolated using vars) and setting values.
>>> joe = 'Joseph'
>>> update('foo', where='name = $joe', name='bob', age=5,
...   vars=locals(), _test=True)
<sql: "UPDATE foo SET age = 5, name = 'bob' WHERE name = 'Joseph'">
delete(table, where=None, using=None, vars=None, _test=False)
Deletes from table with clauses where and using.
>>> name = 'Joe'
>>> delete('foo', where='name = $name', vars=locals(), _test=True)
<sql: "DELETE FROM foo WHERE name = 'Joe'">


A replacement for internalerror that presents a nice page with lots of debug information for the programmer.

(Based on the beautiful 500 page from Django, designed by Wilson Miner.)

emailerrors(email_address, olderror)
Wraps the old internalerror handler (pass as olderror) to additionally email all errors to email_address, to aid in debugging production websites.

Emails contain a normal text traceback as well as an attachment containing the nice debugerror page.


attrget(obj, attr, value=None)
class Form
init(self, *inputs, **kw) inputs is a list of form objects. The only keyword accepted is “validators” which is a list of Validator objects.
class Input(object)
init(self, name, *validators, **attrs) name is the name of the object. It is the default value for the “description” attribute for the HTML form element. The keywords, stored in the dictionary attrs, accepted are: “description”, “value”, “pre”, “post”, “id”, and “class_”
class Textbox(Input)
class Password(Input)
class Textarea(Input)
class Dropdown(Input)
class Radio(Input)
class Checkbox(Input)
class Button(Input)
class Hidden(Input)
class File(Input)
class Validator
class regexp(Validator)


Sorry, this function is really difficult to explain. Maybe some other time.
Outputs an Expires header for delta from now. delta is a timedelta object or a number of seconds.
Outputs a Last-Modified header for datetime.
modified(date=None, etag=None)
redirect(url, status='301 Moved Permanently')
Returns a status redirect to the new URL. url is joined with the base URL so that things like redirect("about") will work properly.
A 302 Found redirect.
A 303 See Other redirect.
A 307 Temporary Redirect redirect.
Converts a standard CGI-style string response into header and output calls.
Same as urllib.urlencode, but supports unicode strings.
>>> urlencode({'text':'foo bar'})
changequery(query=None, **kw)
Imagine you’re at /foo?a=1&b=2. Then changequery(a=3) will return /foo?a=3&b=2 – the same URL but with the arguments you requested changed.
url(path=None, **kw)
Makes url by concatinating web.ctx.homepath and path and the query string created using the arguments.
A function decorator to run a long-running function as a background thread. GOTCHA in postgres: Until the foreground task ends, any db access by background task will necessarily get old data from before the foreground task started because psycopg2 begins a transaction in the foreground task until it quits.
class Reloader
Before every request, checks to see if any loaded modules have changed on disk and, if so, reloads them.
Outputs basic profiling information at the bottom of each response.


runbasic(func, server_address=("", 8080))
Runs a simple HTTP server hosting WSGI app func. The directory static/ is hosted statically.

Based on WsgiServer from Colin Stewart.

runsimple(func, server_address=("", 8080))
Runs CherryPy WSGI server hosting WSGI app func. The directory static/ is hosted statically.


returns True if address is a valid IPv4 address
returns True if port is a valid IPv4 port
validip(ip, defaultaddr="", defaultport=8080)
returns (ip_address, port) from string ip_addr_port
returns either (ip_address, port) or “/path/to/socket” from string_
>>> validaddr('/path/to/socket')
>>> validaddr('8000')
('', 8000)
>>> validaddr('')
('', 8080)
>>> validaddr('')
('', 8000)
>>> validaddr('fff')
Traceback (most recent call last):
ValueError: fff is not a valid IP address/port
Quotes a string for use in a URL.
>>> urlquote('://?f=1&j=1')
>>> urlquote(None)
>>> urlquote(u'\u203d')
Formats a datetime object for use in HTTP headers.
>>> import datetime
>>> httpdate(datetime.datetime(1970, 1, 1, 1, 1, 1))
'Thu, 01 Jan 1970 01:01:01 GMT'
Parses an HTTP date into a datetime object.
>>> parsehttpdate('Thu, 01 Jan 1970 01:01:01 GMT')
datetime.datetime(1970, 1, 1, 1, 1, 1)
Encodes text for raw use in HTML.
>>> htmlquote("<'&\\">")
Decodes text that’s HTML quoted.
>>> htmlunquote('&lt;&#39;&amp;&quot;&gt;')
Converts val so that it’s safe for use in UTF-8 HTML.
>>> websafe("<'&\\">")
>>> websafe(None)
>>> websafe(u'\u203d')


handle(mapping, fvars=None)
Call the appropriate function based on the url to function mapping in mapping. If no module for the function is specified, look up the function in fvars. If fvars is empty, using the caller’s context.

mapping should be a tuple of paired regular expressions with function name substitutions. handle will import modules as necessary.

Returns a 405 Method Not Allowed error for cls.
Returns a method that takes one argument and calls the method named prefix+arg, calling notfound() if there isn’t one. Example:
urls = ('/prefs/(.*)', 'prefs')
class prefs:
    GET = autodelegate('GET_')
    def GET_password(self): pass
    def GET_privacy(self): pass

GET_password would get called for /prefs/password while GET_privacy for GET_privacy gets called for /prefs/privacy.

If a user visits /prefs/password/change then GET_password(self, '/change') is called.

webpyfunc(inp, fvars, autoreload=False)
If inp is a url mapping, returns a function that calls handle.
run(inp, fvars, *middleware)
Starts handling requests. If called in a CGI or FastCGI context, it will follow that protocol. If called from the command line, it will start an HTTP server on the port named in the first command line argument, or, if there is no argument, on port 8080.

input is a callable, then it’s called with no arguments. Otherwise, it’s a mapping object to be passed to handle(...).

Caveat: So that reloader will work correctly, input has to be a variable, it can’t be a tuple passed in directly.

middleware is a list of WSGI middleware which is applied to the resulting WSGI function.


class ParseError(Exception): pass class Parser:
class TemplateParser(Parser)
class Stowage(storage)
class WTF(AssertionError): pass class SecurityError(Exception):
The template seems to be trying to do something naughty.
class Template
class Handle
class Fill(Handle)
class render
frender(fn, *a, **kw)
r”"”Doctest for testing template module.
>>> t = Template
>>> t('1')()
>>> t('$def with ()\n1')()
>>> t('$def with (a)\n$a')(1)
>>> t('$def with (a=0)\n$a')(1)
>>> t('$def with (a=0)\n$a')(a=1)
>>> t('$if 1: 1')()
>>> t('$if 1:\n    1')()
>>> t('$if 0: 0\n$elif 1: 1')()
>>> t('$if 0: 0\n$elif None: 0\n$else: 1')()
>>> t('$if (0 < 1) and (1 < 2): 1')()
>>> t('$for x in [1, 2, 3]: $x')()
>>> t('$for x in []: 0\n$else: 1')()
>>> t('$def with (a)\n$while a and a.pop(): 1')([1, 2, 3])
>>> t('$while 0: 0\n$else: 1')()
>>> t('$ a = 1\n$a')()
>>> t('$# 0')()
>>> t('$def with (d)\n$for k, v in d.iteritems(): $k')({1: 1})
>>> t('$def with (a)\n$(a)')(1)
>>> t('$def with (a)\n$a')(1)
>>> t('$def with (a)\n$a.b')(storage(b=1))
>>> t('$def with (a)\n$a[0]')([1])
>>> t('${0 or 1}')()
>>> t('$ a = [1]\n$a[0]')()
>>> t('$ a = {1: 1}\n$a.keys()[0]')()
>>> t('$ a = []\n$if not a: 1')()
>>> t('$ a = {}\n$if not a: 1')()
>>> t('$ a = -1\n$a')()
>>> t('$ a = "1"\n$a')()
>>> t('$if 1 is 1: 1')()
>>> t('$if not 0: 1')()
>>> t('$if 1:\n    $if 1: 1')()
>>> t('$ a = 1\n$a')()
>>> t('$ a = 1.\n$a')()
>>> t('$({1: 1}.keys()[0])')()
>>> t('$for x in [1, 2, 3]:\n\t$x')()
'    1\n    2\n    3\n'
>>> t('$def with (a)\n$:a')(1)
>>> t('$def with (a)\n$a')(u'\u203d')
>>> t(u'$def with (a)\n$a $:a')(u'\u203d')
'\xe2\x80\xbd \xe2\x80\xbd\n'
>>> t(u'$def with ()\nfoo')()
>>> def f(x): return x
>>> t(u'$def with (f)\n$:f("x")')(f)
>>> t(u'$def with (f)\n$:f(x="x")')(f)
>>> x = t('$var foo: bar')()
>>> str(x)
>>> x.foo

see also template.py doc


class Storage(dict)
A Storage object is like a dictionary except obj.foo can be used in addition to obj['foo'].
>>> o = storage(a=1)
>>> o.a
>>> o['a']
>>> o.a = 2
>>> o['a']
>>> del o.a
>>> o.a
Traceback (most recent call last):
AttributeError: 'a'
storify(mapping, *requireds, **defaults)
Creates a storage object from dictionary mapping, raising KeyError if d doesn’t have all of the keys in requireds and using the default values for keys found in defaults.

For example, storify({'a':1, 'c':3}, b=2, c=0) will return the equivalent of storage({'a':1, 'b':2, 'c':3}).

If a storify value is a list (e.g. multiple values in a form submission), storify returns the last element of the list, unless the key appears in defaults as a list. Thus:

>>> storify({'a':[1, 2]}).a
>>> storify({'a':[1, 2]}, a=[]).a
[1, 2]
>>> storify({'a':1}, a=[]).a
>>> storify({}, a=[]).a

Similarly, if the value has a value attribute, storify will return _its_ value, unless the key appears in defaults` as a dictionary.

>>> storify({'a':storage(value=1)}).a
>>> storify({'a':storage(value=1)}, a={}).a
<Storage {'value': 1}>
>>> storify({}, a={}).a
rstrips(text, remove)
removes the string remove from the right of text
>>> rstrips("foobar", "bar")
lstrips(text, remove)
removes the string remove from the left of text
>>> lstrips("foobar", "foo")
strips(text, remove)
removes the string remove from the both sides of text  »> strips(“foobarfoo”, “foo”) ‘bar’
Encodes text in utf-8.
 » utf8(u’\u1234’) # doctest doesn’t seem to like utf-8 ‘\xe1\x88\xb4’
>>> utf8('hello')
>>> utf8(42)
class TimeoutError(Exception): pass def timelimit(timeout):
A decorator to limit a function to timeout seconds, raising TimeoutError if it takes longer.
>>> import time
>>> def meaningoflife():
...     time.sleep(.2)
...     return 42
>>> timelimit(.1)(meaningoflife)()
Traceback (most recent call last):
TimeoutError: took too long
>>> timelimit(1)(meaningoflife)()

Caveat: The function isn’t stopped after timeout seconds but continues executing in a separate thread. (There seems to be no way to kill a thread.)

inspired by http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/473878

class Memoize
‘Memoizes’ a function, caching its return values for each input.
>>> import time
>>> def meaningoflife():
...     time.sleep(.2)
...     return 42
>>> fastlife = memoize(meaningoflife)
>>> meaningoflife()
>>> timelimit(.1)(meaningoflife)()
Traceback (most recent call last):
TimeoutError: took too long
>>> fastlife()
>>> timelimit(.1)(fastlife)()
re_subm(pat, repl, string)
Like re.sub, but returns the replacement and the match object.
>>> t, m = re_subm('g(oo+)fball', r'f\\1lish', 'goooooofball')
>>> t
>>> m.groups()
group(seq, size)
Returns an iterator over a series of lists of length size from iterable.
>>> list(group([1,2,3,4], 2))
[1, 2], [3, 4](/1, 2], [3, 4)
class IterBetter
Returns an object that can be used as an iterator but can also be used via getitem (although it cannot go backwards – that is, you cannot request iterbetter[0] after requesting iterbetter[1]).
>>> import itertools
>>> c = iterbetter(itertools.count())
>>> c[1]
>>> c[5]
>>> c[3]
Traceback (most recent call last):
IndexError: already passed 3

dictreverse({1: 2, 3: 4}) {2: 1, 4: 3}

dictfind(dictionary, element)
Returns a key whose value in dictionary is element or, if none exists, None.
>>> d = {1:2, 3:4}
>>> dictfind(d, 4)
>>> dictfind(d, 5)
dictfindall(dictionary, element)
Returns the keys whose values in dictionary are element or, if none exists, [].
>>> d = {1:4, 3:4}
>>> dictfindall(d, 4)
[1, 3]
>>> dictfindall(d, 5)
dictincr(dictionary, element)
Increments element in dictionary, setting it to one if it doesn’t exist.
>>> d = {1:2, 3:4}
>>> dictincr(d, 1)
>>> d[1]
>>> dictincr(d, 5)
>>> d[5]
Returns a dictionary consisting of the keys in the argument dictionaries. If they share a key, the value from the last argument is used.
>>> dictadd({1: 0, 2: 0}, {2: 1, 3: 1})
{1: 0, 2: 1, 3: 1}
listget(lst, ind, default=None)
Returns lst[ind] if it exists, default otherwise.
>>> listget(['a'], 0)
>>> listget(['a'], 1)
>>> listget(['a'], 1, 'b')
intget(integer, default=None)
Returns integer as an int or default if it can’t.
>>> intget('3')
>>> intget('3a')
>>> intget('3a', 0)
datestr(then, now=None)
Converts a (UTC) datetime object to a nice string representation.
>>> from datetime import datetime, timedelta
>>> d = datetime(1970, 5, 1)
>>> datestr(d, now=d)
'0 microseconds ago'
>>> for t, v in {
...   timedelta(microseconds=1): '1 microsecond ago',
...   timedelta(microseconds=2): '2 microseconds ago',
...   -timedelta(microseconds=1): '1 microsecond from now',
...   -timedelta(microseconds=2): '2 microseconds from now',
...   timedelta(microseconds=2000): '2 milliseconds ago',
...   timedelta(seconds=2): '2 seconds ago',
...   timedelta(seconds=2*60): '2 minutes ago',
...   timedelta(seconds=2*60*60): '2 hours ago',
...   timedelta(days=2): '2 days ago',
... }.iteritems():
...     assert datestr(d, now=d+t) == v
>>> datestr(datetime(1970, 1, 1), now=d)
'January  1'
>>> datestr(datetime(1969, 1, 1), now=d)
'January  1, 1969'
>>> datestr(datetime(1970, 6, 1), now=d)
'June  1, 1970'
Removes all non-digit characters from string.
>>> numify('800-555-1212')
>>> numify('800.555.1212')
denumify(string, pattern)
Formats string according to pattern, where the letter X gets replaced by characters from string.
>>> denumify("8005551212", "(XXX) XXX-XXXX")
'(800) 555-1212'
Formats a numified datestring properly.
class CaptureStdout
Captures everything func prints to stdout and returns it instead.
>>> def idiot():
...     print "foo"
>>> capturestdout(idiot)()

WARNING: Not threadsafe!

class Profile
Profiles func and returns a tuple containing its output and a string with human-readable profiling information.
>>> import time
>>> out, inf = profile(time.sleep)(.001)
>>> out
>>> inf[:10].strip()
'took 0.0'
tryall(context, prefix=None)
Tries a series of functions and prints their results. context is a dictionary mapping names to values; the value will only be tried if it’s callable.
>>> tryall(dict(j=lambda: True))
j: True
   True: 1

For example, you might have a file test/stuff.py with a series of functions testing various things in it. At the bottom, have a line:

if __name__ == "__main__": tryall(globals())

Then you can run python test/stuff.py and get the results of all the tests.

class ThreadedDict
Takes a dictionary that maps threads to objects. When a thread tries to get or set an attribute or item of the threadeddict, it passes it on to the object for that thread in dictionary.
autoassign(self, locals)
Automatically assigns local variables to self.
>>> self = storage()
>>> autoassign(self, dict(a=1, b=2))
>>> self
<Storage {'a': 1, 'b': 2}>

Generally used in __init__ methods, as in:

def __init__(self, foo, bar, baz=1): autoassign(self, locals())
Converts an integer to base 36 (a useful scheme for human-sayable IDs).
>>> to36(35)
>>> to36(119292)
>>> int(to36(939387374), 36)
>>> to36(0)
>>> to36(-393)
Traceback (most recent call last):
ValueError: must supply a positive integer
Converts text to HTML following the rules of Markdown, but blocking any outside HTML input, so that only the things supported by Markdown can be used. Also converts raw URLs to links.

(requires markdown.py)

sendmail(from_address, to_address, subject, message, headers=None, **kw)
Sends the email message message with mail and envelope headers for from from_address_ to to_address with subject. Additional email headers can be specified with the dictionary `headers.

If web.config.smtp_server is set, it will send the message to that SMTP server. Otherwise it will look for /usr/lib/sendmail, the typical location for the sendmail-style binary.


Return a 400 Bad Request error.
Returns a 404 Not Found error.
Returns a 410 Gone error.
Returns a 500 Internal Server error.
header(hdr, value, unique=False)
Adds the header hdr: value with the response.

If unique is True and a header with that name already exists, it doesn’t add a new one.

Appends string_ to the response.
input(*requireds, **defaults)
Returns a storage object with the GET and POST arguments. See storify for how requireds and defaults work.
Returns the data sent with the request.
setcookie(name, value, expires="", domain=None, secure=False)
Sets a cookie.
cookies(*requireds, **defaults)
Returns a storage object with all the cookies in it. See storify for how requireds and defaults work.
Prints a prettyprinted version of args to stderr.
Loads a new context for the thread.

You can ask for a function to be run at loadtime by adding it to the dictionary loadhooks.

Unloads the context for the thread.

You can ask for a function to be run at loadtime by adding it ot the dictionary unloadhooks.

wsgifunc(func, *middleware)
Returns a WSGI-compatible function from a webpy-function.
A storage object containing various information about the request:
`environ` (aka `env`)
   : A dictionary containing the standard WSGI environment variables.

   : The domain (`Host` header) requested by the user.

   : The base path for the application.

   : The IP address of the requester.

   : The HTTP method used.

   : The path request.
   : If there are no query arguments, the empty string. Otherwise, a `?` followed
     by the query string.

   : The full path requested, including query arguments (`== path + query`).

### Response Data

`status` (default: "200 OK")
   : The status code to be used in the response.

   : A list of 2-tuples to be used in the response.

   : A string to be used as the response. ## wsgi.py
runfcgi(func, addr=('localhost', 8000))
Runs a WSGI function as a FastCGI server.
runscgi(func, addr=('localhost', 4000))
Runs a WSGI function as an SCGI server.
Runs a WSGI-compatible func using FCGI, SCGI, or a simple web server, as appropriate based on context and sys.argv.