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class MergeDict:
"""
A simple class for creating new "virtual" dictionaries that actualy look
up values in more than one dictionary, passed in the constructor.
"""
def __init__(self, *dicts):
self.dicts = dicts
def __getitem__(self, key):
for dict in self.dicts:
try:
return dict[key]
except KeyError:
pass
raise KeyError
def get(self, key, default):
try:
return self[key]
except KeyError:
return default
def getlist(self, key):
for dict in self.dicts:
try:
return dict.getlist(key)
except KeyError:
pass
raise KeyError
def items(self):
item_list = []
for dict in self.dicts:
item_list.extend(dict.items())
return item_list
def has_key(self, key):
for dict in self.dicts:
if dict.has_key(key):
return True
return False
class MultiValueDictKeyError(KeyError):
pass
class MultiValueDict:
"""
A dictionary-like class customized to deal with multiple values for the same key.
>>> d = MultiValueDict({'name': ['Adrian', 'Simon'], 'position': ['Developer']})
>>> d['name']
'Simon'
>>> d.getlist('name')
['Adrian', 'Simon']
>>> d.get('lastname', 'nonexistent')
'nonexistent'
>>> d.setlist('lastname', ['Holovaty', 'Willison'])
This class exists to solve the irritating problem raised by cgi.parse_qs,
which returns a list for every key, even though most Web forms submit
single name-value pairs.
"""
def __init__(self, key_to_list_mapping=None):
self.data = key_to_list_mapping or {}
def __repr__(self):
return repr(self.data)
def __getitem__(self, key):
"Returns the data value for this key; raises KeyError if not found"
if self.data.has_key(key):
try:
return self.data[key][-1] # in case of duplicates, use last value ([-1])
except IndexError:
return []
raise MultiValueDictKeyError, "Key '%s' not found in MultiValueDict %s" % (key, self.data)
def __setitem__(self, key, value):
self.data[key] = [value]
def __len__(self):
return len(self.data)
def get(self, key, default):
"Returns the default value if the requested data doesn't exist"
try:
val = self[key]
except (KeyError, IndexError):
return default
if val == []:
return default
return val
def getlist(self, key):
"Returns an empty list if the requested data doesn't exist"
try:
return self.data[key]
except KeyError:
return []
def setlist(self, key, list_):
self.data[key] = list_
def appendlist(self, key, item):
"Appends an item to the internal list associated with key"
try:
self.data[key].append(item)
except KeyError:
self.data[key] = [item]
def has_key(self, key):
return self.data.has_key(key)
def items(self):
# we don't just return self.data.items() here, because we want to use
# self.__getitem__() to access the values as *strings*, not lists
return [(key, self[key]) for key in self.data.keys()]
def keys(self):
return self.data.keys()
def update(self, other_dict):
if isinstance(other_dict, MultiValueDict):
for key, value_list in other_dict.data.items():
self.data.setdefault(key, []).extend(value_list)
elif type(other_dict) == type({}):
for key, value in other_dict.items():
self.data.setdefault(key, []).append(value)
else:
raise ValueError, "MultiValueDict.update() takes either a MultiValueDict or dictionary"
def copy(self):
"Returns a copy of this object"
import copy
cp = copy.deepcopy(self)
return cp
class DotExpandedDict(dict):
"""
A special dictionary constructor that takes a dictionary in which the keys
may contain dots to specify inner dictionaries. It's confusing, but this
example should make sense.
>>> d = DotExpandedDict({'person.1.firstname': ['Simon'],
'person.1.lastname': ['Willison'],
'person.2.firstname': ['Adrian'],
'person.2.lastname': ['Holovaty']})
>>> d
{'person': {'1': {'lastname': ['Willison'], 'firstname': ['Simon']},
'2': {'lastname': ['Holovaty'], 'firstname': ['Adrian']}}}
>>> d['person']
{'1': {'firstname': ['Simon'], 'lastname': ['Willison'],
'2': {'firstname': ['Adrian'], 'lastname': ['Holovaty']}
>>> d['person']['1']
{'firstname': ['Simon'], 'lastname': ['Willison']}
# Gotcha: Results are unpredictable if the dots are "uneven":
>>> DotExpandedDict({'c.1': 2, 'c.2': 3, 'c': 1})
>>> {'c': 1}
"""
def __init__(self, key_to_list_mapping):
for k, v in key_to_list_mapping.items():
current = self
bits = k.split('.')
for bit in bits[:-1]:
current = current.setdefault(bit, {})
# Now assign value to current position
try:
current[bits[-1]] = v
except TypeError: # Special-case if current isn't a dict.
current = {bits[-1]: v}
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