Werkzeug provides some subclasses of common Python objects to extend them with additional features. Some of them are used to make them immutable, others are used to change some semantics to better work with HTTP.
General Purpose
Changed in version 0.6: The general purpose classes are now pickleable in each protocol as long
as the contained objects are pickleable. This means that the
FileMultiDict
won’t be pickleable as soon as it contains a
file.
class werkzeug.datastructures.TypeConversionDict
Works like a regular dict but the get()
method can perform
type conversions. MultiDict
and CombinedMultiDict
are subclasses of this class and provide the same feature.
New in version 0.5.
get(key, default=None, type=None)
Return the default value if the requested data doesn’t exist.
If [UNKNOWN NODE title_reference] is provided and is a callable it should convert the value,
return it or raise a ValueError
if that is not possible. In
this case the function will return the default as if the value was not
found:
- key – The key to be looked up.
- default – The default value to be returned if the key can’t be looked up. If not further specified [UNKNOWN NODE title_reference] is returned.
- type – A callable that is used to cast the value in the
MultiDict
. If aValueError
is raised by this callable the default value is returned.
class werkzeug.datastructures.ImmutableTypeConversionDict
Works like a TypeConversionDict
but does not support
modifications.
New in version 0.5.
copy()
Return a shallow mutable copy of this object. Keep in mind that
the standard library’s copy()
function is a no-op for this class
like for any other python immutable type (eg: tuple
).
class werkzeug.datastructures.MultiDict(mapping=None)
A MultiDict
is a dictionary subclass customized to deal with
multiple values for the same key which is for example used by the parsing
functions in the wrappers. This is necessary because some HTML form
elements pass multiple values for the same key.
MultiDict
implements all standard dictionary methods.
Internally, it saves all values for a key as a list, but the standard dict
access methods will only return the first value for a key. If you want to
gain access to the other values, too, you have to use the [UNKNOWN NODE title_reference] methods as
explained below.
Basic Usage:
[UNKNOWN NODE doctest_block]It behaves like a normal dict thus all dict functions will only return the first value when multiple values for one key are found.
From Werkzeug 0.3 onwards, the [UNKNOWN NODE title_reference] raised by this class is also a
subclass of the BadRequest
HTTP exception and will
render a page for a 400 BAD REQUEST
if caught in a catch-all for HTTP
exceptions.
A MultiDict
can be constructed from an iterable of
(key, value)
tuples, a dict, a MultiDict
or from Werkzeug 0.2
onwards some keyword parameters.
MultiDict
. Either a
regular dict, an iterable of (key, value)
tuples
or [UNKNOWN NODE title_reference].add(key, value)
Adds a new value for the key.
New in version 0.6.
- key – the key for the value.
- value – the value to add.
clear() → None. Remove all items from D.
copy()
Return a shallow copy of this object.
deepcopy(memo=None)
Return a deep copy of this object.
fromkeys(S[, v]) → New dict with keys from S and values equal to v.
v defaults to None.
get(key, default=None, type=None)
Return the default value if the requested data doesn’t exist.
If [UNKNOWN NODE title_reference] is provided and is a callable it should convert the value,
return it or raise a ValueError
if that is not possible. In
this case the function will return the default as if the value was not
found:
- key – The key to be looked up.
- default – The default value to be returned if the key can’t be looked up. If not further specified [UNKNOWN NODE title_reference] is returned.
- type – A callable that is used to cast the value in the
MultiDict
. If aValueError
is raised by this callable the default value is returned.
getlist(key, type=None)
Return the list of items for a given key. If that key is not in the [UNKNOWN NODE title_reference], the return value will be an empty list. Just as [UNKNOWN NODE title_reference] [UNKNOWN NODE title_reference] accepts a [UNKNOWN NODE title_reference] parameter. All items will be converted with the callable defined there.
- key – The key to be looked up.
- type – A callable that is used to cast the value in the
MultiDict
. If aValueError
is raised by this callable the value will be removed from the list.
list
of all the values for the key.has_key(k) → True if D has a key k, else False
items(*a, **kw)
Like iteritems()
, but returns a list.
iteritems(multi=False)
Return an iterator of (key, value)
pairs.
iterlists()
Return a list of (key, values)
pairs, where values is the list
of all values associated with the key.
iterlistvalues()
Return an iterator of all values associated with a key. Zipping
keys()
and this is the same as calling lists()
:
itervalues()
Returns an iterator of the first value on every key’s value list.
keys(*a, **kw)
Like iterkeys()
, but returns a list.
lists(*a, **kw)
Like iterlists()
, but returns a list.
listvalues(*a, **kw)
Like iterlistvalues()
, but returns a list.
pop(key, default=no value)
Pop the first item for a list on the dict. Afterwards the key is removed from the dict, so additional values are discarded:
[UNKNOWN NODE doctest_block]- key – the key to pop.
- default – if provided the value to return if the key was not in the dictionary.
popitem()
Pop an item from the dict.
popitemlist()
Pop a (key, list)
tuple from the dict.
poplist(key)
Pop the list for a key from the dict. If the key is not in the dict an empty list is returned.
Changed in version 0.5: If the key does no longer exist a list is returned instead of raising an error.
setdefault(key, default=None)
Returns the value for the key if it is in the dict, otherwise it returns [UNKNOWN NODE title_reference] and sets that value for [UNKNOWN NODE title_reference].
- key – The key to be looked up.
- default – The default value to be returned if the key is not in the dict. If not further specified it’s [UNKNOWN NODE title_reference].
setlist(key, new_list)
Remove the old values for a key and add new ones. Note that the list you pass the values in will be shallow-copied before it is inserted in the dictionary.
[UNKNOWN NODE doctest_block]- key – The key for which the values are set.
- new_list – An iterable with the new values for the key. Old values are removed first.
setlistdefault(key, default_list=None)
Like [UNKNOWN NODE title_reference] but sets multiple values. The list returned is not a copy, but the list that is actually used internally. This means that you can put new values into the dict by appending items to the list:
[UNKNOWN NODE doctest_block]- key – The key to be looked up.
- default_list – An iterable of default values. It is either copied (in case it was a list) or converted into a list before returned.
list
to_dict(flat=True)
Return the contents as regular dict. If [UNKNOWN NODE title_reference] is [UNKNOWN NODE title_reference] the returned dict will only have the first item present, if [UNKNOWN NODE title_reference] is [UNKNOWN NODE title_reference] all values will be returned as lists.
dict
update(other_dict)
update() extends rather than replaces existing key lists:
[UNKNOWN NODE doctest_block]If the value list for a key in other_dict
is empty, no new values
will be added to the dict and the key will not be created:
values(*a, **kw)
Like itervalues()
, but returns a list.
viewitems(*a, **kw)
“”“[UNKNOWN NODE title_reference] object providing a view on items”“”
viewkeys(*a, **kw)
“”“[UNKNOWN NODE title_reference] object providing a view on keys”“”
viewlists(*a, **kw)
“”“[UNKNOWN NODE title_reference] object providing a view on lists”“”
viewlistvalues(*a, **kw)
“”“[UNKNOWN NODE title_reference] object providing a view on listvalues”“”
viewvalues(*a, **kw)
“”“[UNKNOWN NODE title_reference] object providing a view on values”“”
class werkzeug.datastructures.OrderedMultiDict(mapping=None)
Works like a regular MultiDict
but preserves the
order of the fields. To convert the ordered multi dict into a
list you can use the items()
method and pass it multi=True
.
In general an OrderedMultiDict
is an order of magnitude
slower than a MultiDict
.
note
Due to a limitation in Python you cannot convert an ordered
multi dict into a regular dict by using dict(multidict)
.
Instead you have to use the to_dict()
method, otherwise
the internal bucket objects are exposed.
class werkzeug.datastructures.ImmutableMultiDict(mapping=None)
An immutable MultiDict
.
New in version 0.5.
copy()
Return a shallow mutable copy of this object. Keep in mind that
the standard library’s copy()
function is a no-op for this class
like for any other python immutable type (eg: tuple
).
class werkzeug.datastructures.ImmutableOrderedMultiDict(mapping=None)
An immutable OrderedMultiDict
.
New in version 0.6.
copy()
Return a shallow mutable copy of this object. Keep in mind that
the standard library’s copy()
function is a no-op for this class
like for any other python immutable type (eg: tuple
).
class werkzeug.datastructures.CombinedMultiDict(dicts=None)
A read only MultiDict
that you can pass multiple MultiDict
instances as sequence and it will combine the return values of all wrapped
dicts:
This works for all read operations and will raise a [UNKNOWN NODE title_reference] for methods that usually change data which isn’t possible.
From Werkzeug 0.3 onwards, the [UNKNOWN NODE title_reference] raised by this class is also a
subclass of the BadRequest
HTTP exception and will
render a page for a 400 BAD REQUEST
if caught in a catch-all for HTTP
exceptions.
class werkzeug.datastructures.ImmutableDict
An immutable dict
.
New in version 0.5.
copy()
Return a shallow mutable copy of this object. Keep in mind that
the standard library’s copy()
function is a no-op for this class
like for any other python immutable type (eg: tuple
).
class werkzeug.datastructures.ImmutableList
An immutable list
.
New in version 0.5.
class werkzeug.datastructures.FileMultiDict(mapping=None)
A special MultiDict
that has convenience methods to add
files to it. This is used for EnvironBuilder
and generally
useful for unittesting.
New in version 0.5.
add_file(name, file, filename=None, content_type=None)
Adds a new file to the dict. [UNKNOWN NODE title_reference] can be a file name or
a file
-like or a FileStorage
object.
- name – the name of the field.
- file – a filename or
file
-like object - filename – an optional filename
- content_type – an optional content type
Others
class werkzeug.datastructures.FileStorage(stream=None, filename=None, name=None, content_type=None, content_length=None, headers=None)
The FileStorage
class is a thin wrapper over incoming files.
It is used by the request object to represent uploaded files. All the
attributes of the wrapper stream are proxied by the file storage so
it’s possible to do storage.read()
instead of the long form
storage.stream.read()
.
stream
The input stream for the uploaded file. This usually points to an open temporary file.
filename
The filename of the file on the client.
name
The name of the form field.
headers
The multipart headers as Headers
object. This usually contains
irrelevant information but in combination with custom multipart requests
the raw headers might be interesting.
New in version 0.6.
close()
Close the underlying file if possible.
content_length
The content-length sent in the header. Usually not available
content_type
The content-type sent in the header. Usually not available
mimetype
Like content_type
, but without parameters (eg, without
charset, type etc.) and always lowercase. For example if the content
type is text/HTML; charset=utf-8
the mimetype would be
'text/html'
.
New in version 0.7.
mimetype_params
The mimetype parameters as dict. For example if the content
type is text/html; charset=utf-8
the params would be
{'charset': 'utf-8'}
.
New in version 0.7.
save(dst, buffer_size=16384)
Save the file to a destination path or file object. If the destination is a file object you have to close it yourself after the call. The buffer size is the number of bytes held in memory during the copy process. It defaults to 16KB.
For secure file saving also have a look at secure_filename()
.
- dst – a filename or open file object the uploaded file is saved to.
- buffer_size – the size of the buffer. This works the same as
the [UNKNOWN NODE title_reference] parameter of
shutil.copyfileobj()
.