webob.multidict
-- multi-value dictionary object¶
multidict¶
Several parts of WebOb use a "multidict", which is a dictionary where a key can
have multiple values. The quintessential example is a query string like
?pref=red&pref=blue
. The pref
variable has two values, red
and
blue
.
In a multidict, when you do request.GET['pref']
, you'll get back only
'blue'
(the last value of pref
). Sometimes returning a string and
other times returning a list is a cause of frequent exceptions. If you want
all the values back, use request.GET.getall('pref')
. If you want to be
sure there is one and only one value, use request.GET.getone('pref')
,
which will raise an exception if there is zero or more than one value for
pref
.
When you use operations like request.GET.items()
, you'll get back something
like [('pref', 'red'), ('pref', 'blue')]
. All the key/value pairs will
show up. Similarly request.GET.keys()
returns ['pref', 'pref']
.
Multidict is a view on a list of tuples; all the keys are ordered, and all the
values are ordered.
Gives a multi-value dictionary object (MultiDict) plus several wrappers
-
class
webob.multidict.
MultiDict
(*args, **kw)¶ An ordered dictionary that can have multiple values for each key. Adds the methods getall, getone, mixed and extend and add to the normal dictionary interface.
-
classmethod
view_list
(lst)¶ Create a dict that is a view on the given list
-
classmethod
from_fieldstorage
(fs)¶ Create a dict from a cgi.FieldStorage instance
-
add
(key, value)¶ Add the key and value, not overwriting any previous value.
-
getall
(key)¶ Return a list of all values matching the key (may be an empty list)
-
getone
(key)¶ Get one value matching the key, raising a KeyError if multiple values were found.
-
mixed
()¶ Returns a dictionary where the values are either single values, or a list of values when a key/value appears more than once in this dictionary. This is similar to the kind of dictionary often used to represent the variables in a web request.
-
dict_of_lists
()¶ Returns a dictionary where each key is associated with a list of values.
-
clear
() → None. Remove all items from D.¶
-
setdefault
(k[, d]) → D.get(k,d), also set D[k]=d if k not in D¶
-
pop
(k[, d]) → v, remove specified key and return the corresponding value.¶ If key is not found, d is returned if given, otherwise KeyError is raised.
-
popitem
() → (k, v), remove and return some (key, value) pair¶ as a 2-tuple; but raise KeyError if D is empty.
-
update
([E, ]**F) → None. Update D from mapping/iterable E and F.¶ If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v
-
get
(k[, d]) → D[k] if k in D, else d. d defaults to None.¶
-
classmethod
-
class
webob.multidict.
NestedMultiDict
(*dicts)¶ Wraps several MultiDict objects, treating it as one large MultiDict
-
getall
(key)¶ Return a list of all values matching the key (may be an empty list)
-
-
class
webob.multidict.
NoVars
(reason=None)¶ Represents no variables; used when no variables are applicable.
This is read-only