def test_lru_cache_clear():
cache = LRUCache(capacity=3)
cache["a"] = 1
cache["b"] = 2
cache.clear()
assert cache.lru == []
def test_lru_cache_get():
cache = LRUCache(capacity=3)
cache["a"] = 1
cache["b"] = 1
cache["c"] = 1
cache.get("a")
cache["d"] = 4
assert cache.lru == ["c", "a", "d"]
def test_lru_cache_set_multiple():
cache = LRUCache(capacity=3)
cache["a"] = 1
cache["a"] = 2
cache["a"] = 3
cache["a"] = 4
assert cache.lru == ["a"]
def __init__(self, storage, cache_size=10):
"""
Get access to a table.
:param storage: Access to the storage
:type storage: StorageProxyus
:param cache_size: Maximum size of query cache.
"""
self._storage = storage
self._query_cache = LRUCache(capacity=cache_size)
data = self._read()
if data:
self._last_id = max(i for i in data)
else:
self._last_id = 0
def test_lru_cache():
cache = LRUCache(capacity=3)
cache["a"] = 1
cache["b"] = 2
cache["c"] = 3
_ = cache["a"] # move to front in lru queue
cache["d"] = 4 # move oldest item out of lru queue
assert cache.lru == ["c", "a", "d"]
class DBTable(Table):
"""
Represents a single TinyDB Table.
"""
def __init__(self, storage, cache_size=10):
"""
Get access to a table.
:param storage: Access to the storage
:type storage: StorageProxyus
:param cache_size: Maximum size of query cache.
"""
self._storage = storage
self._query_cache = LRUCache(capacity=cache_size)
data = self._read()
if data:
self._last_id = max(i for i in data)
else:
self._last_id = 0
def _read(self):
"""
Reading access to the DB.
:returns: all values
:rtype: dict
"""
return self._storage.read()
def _write(self, values):
"""
Writing access to the DB.
:param values: the new values to write
:type values: dict
"""
self._query_cache.clear()
self._storage.write(values)
def __init__(self, name, db, cache_size=10):
"""
Get access to a table.
:param name: The name of the table.
:type name: str
:param db: The parent database.
:type db: tinydb.database.TinyDB
:param cache_size: Maximum size of query cache.
"""
self.name = name
self._db = db
self._query_cache = LRUCache(capacity=cache_size)
old_ids = self._read().keys()
if old_ids:
self._last_id = max(i for i in old_ids)
else:
self._last_id = 0
def test_lru_cache_delete():
cache = LRUCache(capacity=3)
cache["a"] = 1
cache["b"] = 2
del cache["a"]
try:
del cache['f']
except KeyError:
pass
assert cache.lru == ["b"]
def test_lru_cache():
cache = LRUCache(capacity=3)
cache["a"] = 1
cache["b"] = 2
cache["c"] = 3
_ = cache["a"] # move to front in lru queue
cache["d"] = 4 # move oldest item out of lru queue
try:
_ = cache['f']
except KeyError:
pass
assert cache.lru == ["c", "a", "d"]
def __init__(self, storage, cache_size=10):
"""
Get access to a table.
:param storage: Access to the storage
:type storage: StorageProxyus
:param cache_size: Maximum size of query cache.
"""
self._storage = storage
self._query_cache = LRUCache(capacity=cache_size)
data = self._read()
if data:
self._last_id = max(i for i in data)
else:
self._last_id = 0
def __init__(self, name, db, cache_size=10):
"""
Get access to a table.
:param name: The name of the table.
:type name: str
:param db: The parent database.
:type db: tinydb.database.TinyDB
:param cache_size: Maximum size of query cache.
"""
self.name = name
self._db = db
self._query_cache = LRUCache(capacity=cache_size)
old_ids = self._read().keys()
if old_ids:
self._last_id = max(i for i in old_ids)
else:
self._last_id = 0
class Table(object):
def __init__(self, cache_size=10):
"""
Implement a single table object.
"""
self._query_cache = LRUCache(capacity=cache_size)
self.data = {}
self.column_type = {}
self._last_id = 0
def process_elements(self, func, cond=None, eids=None):
"""
Helper function for processing all elements specified by condition
or IDs.
A repeating pattern in TinyDB is to run some code on all elements
that match a condition or are specified by their ID. This is
implemented in this function.
The function passed as ``func`` has to be a callable. It's first
argument will be the data currently in the database. It's second
argument is the element ID of the currently processed element.
See: :meth:`~.update`, :meth:`.remove`
:param func: the function to execute on every included element.
first argument: all data
second argument: the current eid
:param cond: elements to use, or
:param eids: elements to use
:returns: the element IDs that were affected during processed
"""
data = self._read()
if eids is not None:
# Processed element specified by id
for eid in eids:
func(data, eid)
else:
# Collect affected eids
eids = []
# Processed elements specified by condition
for eid in list(data):
if cond(data[eid]):
func(data, eid)
eids.append(eid)
self._write(data)
return eids
def clear_cache(self):
"""
Clear the query cache.
A simple helper that clears the internal query cache.
"""
self._query_cache.clear()
def _get_next_id(self):
"""
Increment the ID used the last time and return it
"""
current_id = self._last_id + 1
self._last_id = current_id
return current_id
def _read(self):
"""
Reading access to the DB.
:returns: all values
:rtype: dict
"""
return self.data
def _write(self, values):
"""
Writing access to the DB.
:param values: the new values to write
:type values: dict
"""
self._query_cache.clear()
self.data = values
def __len__(self):
"""
Get the total number of elements in the table.
"""
return len(self._read())
def all(self):
"""
Get all elements stored in the table.
:returns: a list with all elements.
:rtype: list[Element]
"""
return list(itervalues(self._read()))
def get_column_type(self, name):
"""
Get the type of a specified column.
"""
return self.column_type[name]
@property
def column_name(self):
"""
Get all the column names.
"""
names = None
if self.data:
names = self.data[0].keys()
return names
def insert(self, element):
"""
Insert a new element into the table.
:param element: the element to insert
:returns: the inserted element's ID
"""
eid = self._get_next_id()
if not isinstance(element, dict):
raise ValueError('Element is not a dictionary')
data = self._read()
data[eid] = element
self._write(data)
if not self.column_type:
for key, val in element.iteritems():
self.column_type[key] = type(val)
return eid
def insert_multiple(self, elements):
"""
Insert multiple elements into the table.
:param elements: a list of elements to insert
:returns: a list containing the inserted elements' IDs
"""
eids = []
data = self._read()
for element in elements:
eid = self._get_next_id()
eids.append(eid)
data[eid] = element
self._write(data)
if not self.column_type:
for key, val in elements[0].iteritems():
self.column_type[key] = type(val)
return eids
def remove(self, cond=None, eids=None):
"""
Remove all matching elements.
:param cond: the condition to check against
:type cond: query
:param eids: a list of element IDs
:type eids: list
:returns: a list containing the removed element's ID
"""
return self.process_elements(lambda data, eid: data.pop(eid), cond,
eids)
def update(self, fields, cond=None, eids=None):
"""
Update all matching elements to have a given set of fields.
:param fields: the fields that the matching elements will have
or a method that will update the elements
:type fields: dict | dict -> None
:param cond: which elements to update
:type cond: query
:param eids: a list of element IDs
:type eids: list
:returns: a list containing the updated element's ID
"""
if callable(fields):
return self.process_elements(lambda data, eid: fields(data[eid]),
cond, eids)
else:
return self.process_elements(
lambda data, eid: data[eid].update(fields), cond, eids)
def purge(self):
"""
Purge the table by removing all elements.
"""
self._write({})
self._last_id = 0
def search(self, cond):
"""
Search for all elements matching a 'where' cond.
:param cond: the condition to check against
:type cond: Query
:returns: list of matching elements
:rtype: list[Element]
"""
if cond in self._query_cache:
return self._query_cache[cond][:]
elements = [element for element in self.all() if cond(element)]
self._query_cache[cond] = elements
return elements[:]
def get(self, cond=None, eid=None):
"""
Get exactly one element specified by a query or and ID.
Returns ``None`` if the element doesn't exist
:param cond: the condition to check against
:type cond: Query
:param eid: the element's ID
:returns: the element or None
:rtype: Element | None
"""
# Cannot use process_elements here because we want to return a
# specific element
if eid is not None:
# Element specified by ID
return self._read().get(eid, None)
# Element specified by condition
for element in self.all():
if cond(element):
return element
def denotation(self, name, cond=None):
"""
Get the denotation of a query.
:param name: the column name
:type name: string
:param cond: the condition to check against
:type cond: Query
:returns: the denotation
:rtype: list (not set)
"""
rows = []
if cond:
rows = self.search(cond)
else:
rows = self.all()
entries = [r[name] for r in rows]
return entries
def denotation_flatten(self, name, cond=None):
"""
Get the flattened denotation list of a query.
"""
return reduce(lambda x, y: x + y, self.denotation(name, cond))
def denotation_set(self, name, cond=None):
"""
Get the denotation set of a query.
"""
return set(self.denotation(name, cond))
def denotation_flatten_set(self, name, cond=None):
"""
Get the flattened denotation set of a query.
"""
return set(self.denotation_flatten(name, cond))
def count(self, cond=None):
"""
Count the elements matching a condition.
:param cond: the condition use
:type cond: Query
"""
if cond:
return len(self.search(cond))
else:
return len(self.all())
def argmax(self, name):
"""
Get the row where the value in the given column is the maximum
"""
s = sorted(self.all(), key=lambda k: k[name], reverse=True)
targmax = [s[0]]
for i in xrange(1, len(s)):
if s[i] == s[0]:
targmax.append(s[i])
else:
break
return targmax
def argmin(self, name):
"""
Get the row where the value in the given column is the minimum
"""
s = sorted(self.all(), key=lambda k: k[name])
targmin = [s[0]]
for i in xrange(1, len(s)):
if s[i] == s[0]:
targmin.append(s[i])
else:
break
return targmin
def count_argmax(self, name):
"""
Get the row where the amount of values in the given column is the maximum
"""
s = sorted(self.all(), key=lambda k: len(k[name]), reverse=True)
cargmax = [s[0]]
for i in xrange(1, len(s)):
if s[i] == s[0]:
cargmax.append(s[i])
else:
break
return cargmax
def count_argmin(self, name):
"""
Get the row where the amount of values in the given column is the minimum
"""
s = sorted(self.all(), key=lambda k: len(k[name]))
cargmin = [s[0]]
for i in xrange(1, len(s)):
if s[i] == s[0]:
cargmin.append(s[i])
else:
break
return cargmin
def contains(self, cond=None, eids=None):
"""
Check wether the database contains an element matching a condition or
an ID.
If ``eids`` is set, it checks if the db contains an element with one
of the specified.
:param cond: the condition use
:type cond: Query
:param eids: the element IDs to look for
"""
if eids is not None:
# Elements specified by ID
return any(self.get(eid=eid) for eid in eids)
# Element specified by condition
return self.get(cond) is not None
class Table(object):
"""
Represents a single TinyDB Table.
"""
def __init__(self, name, db, cache_size=10):
"""
Get access to a table.
:param name: The name of the table.
:type name: str
:param db: The parent database.
:type db: tinydb.database.TinyDB
:param cache_size: Maximum size of query cache.
"""
self.name = name
self._db = db
self._query_cache = LRUCache(capacity=cache_size)
old_ids = self._read().keys()
if old_ids:
self._last_id = max(i for i in old_ids)
else:
self._last_id = 0
def process_elements(self, func, cond=None, eids=None):
"""
Helper function for processing all elements specified by condition
or IDs.
A repeating pattern in TinyDB is to run some code on all elements
that match a condition or are specified by their ID. This is
implemented in this function.
The function passed as ``func`` has to be a callable. It's first
argument will be the data currently in the database. It's second
argument is the element ID of the currently processed element.
See: :meth:`~.update`, :meth:`.remove`
:param func: the function to execute on every included element.
first argument: all data
second argument: the current eid
:param cond: elements to use
:param eids: elements to use
"""
data = self._read()
if eids is not None:
# Processed element specified by id
for eid in eids:
func(data, eid)
else:
# Processed elements specified by condition
for eid in list(data):
if cond(data[eid]):
func(data, eid)
self._write(data)
def _get_next_id(self):
"""
Increment the ID used the last time and return it
"""
current_id = self._last_id + 1
self._last_id = current_id
return current_id
def _read(self):
"""
Reading access to the DB.
:returns: all values
:rtype: dict
"""
raw_data = self._db._read_table(self.name)
data = {}
for key in list(raw_data):
eid = int(key)
data[eid] = Element(raw_data[key], eid)
return data
def _write(self, values):
"""
Writing access to the DB.
:param values: the new values to write
:type values: dict
"""
self._query_cache.clear()
self._db._write_table(values, self.name)
def __len__(self):
"""
Get the total number of elements in the table.
"""
return len(self._read())
def all(self):
"""
Get all elements stored in the table.
:returns: a list with all elements.
:rtype: list[Element]
"""
return list(self._read().values())
def insert(self, element):
"""
Insert a new element into the table.
:param element: the element to insert
:returns: the inserted element's ID
"""
eid = self._get_next_id()
data = self._read()
data[eid] = element
self._write(data)
return eid
def insert_multiple(self, elements):
"""
Insert multiple elements into the table.
:param elements: a list of elements to insert
:returns: a list containing the inserted elements' IDs
"""
eids = []
data = self._read()
for element in elements:
eid = self._get_next_id()
eids.append(eid)
data[eid] = element
self._write(data)
return eids
def remove(self, cond=None, eids=None):
"""
Remove all matching elements.
:param cond: the condition to check against
:type cond: query
:param eids: a list of element IDs
:type eids: list
"""
self.process_elements(lambda data, eid: data.pop(eid), cond, eids)
def update(self, fields, cond=None, eids=None):
"""
Update all matching elements to have a given set of fields.
:param fields: the fields that the matching elements will have
or a method that will update the elements
:type fields: dict | (dict, int) -> None
:param cond: which elements to update
:type cond: query
:param eids: a list of element IDs
:type eids: list
"""
if callable(fields):
_update = lambda data, eid: fields(data[eid])
else:
_update = lambda data, eid: data[eid].update(fields)
self.process_elements(_update, cond, eids)
def purge(self):
"""
Purge the table by removing all elements.
"""
self._write({})
self._last_id = 0
def search(self, cond):
"""
Search for all elements matching a 'where' cond.
:param cond: the condition to check against
:type cond: Query
:returns: list of matching elements
:rtype: list[Element]
"""
if cond in self._query_cache:
return self._query_cache[cond]
elements = [element for element in self.all() if cond(element)]
self._query_cache[cond] = elements
return elements
def get(self, cond=None, eid=None):
"""
Get exactly one element specified by a query or and ID.
Returns ``None`` if the element doesn't exist
:param cond: the condition to check against
:type cond: Query
:param eid: the element's ID
:returns: the element or None
:rtype: Element | None
"""
# Cannot use process_elements here because we want to return a
# specific element
if eid is not None:
# Element specified by ID
return self._read().get(eid, None)
# Element specified by condition
for element in self.all():
if cond(element):
return element
def count(self, cond):
"""
Count the elements matching a condition.
:param cond: the condition use
:type cond: Query
"""
return len(self.search(cond))
def contains(self, cond=None, eids=None):
"""
Check wether the database contains an element matching a condition or
an ID.
If ``eids`` is set, it checks if the db contains an element with one
of the specified.
:param cond: the condition use
:type cond: Query
:param eids: the element IDs to look for
"""
if eids is not None:
# Elements specified by ID
return any(self.get(eid=eid) for eid in eids)
# Element specified by condition
return self.get(cond) is not None
def __enter__(self):
"""
Allow the database to be used as a context manager.
:return: the table instance
"""
return self
def __exit__(self, *args):
"""
Try to close the storage after being used as a context manager.
"""
_ = args
self._db._storage.close()
close = __exit__
def test_lru_cache_unlimited_explicit():
cache = LRUCache(capacity=None)
for i in range(100):
cache[i] = i
assert len(cache.lru) == 100
def test_lru_cache_unlimited():
cache = LRUCache()
for i in range(100):
cache[i] = i
assert len(cache.lru) == 100
class Table(object):
"""
Represents a single TinyDB Table.
"""
def __init__(self, storage, cache_size=10):
"""
Get access to a table.
:param storage: Access to the storage
:type storage: StorageProxyus
:param cache_size: Maximum size of query cache.
"""
self._storage = storage
self._query_cache = LRUCache(capacity=cache_size)
data = self._read()
if data:
self._last_id = max(i for i in data)
else:
self._last_id = 0
def process_elements(self, func, cond=None, eids=None):
"""
Helper function for processing all elements specified by condition
or IDs.
A repeating pattern in TinyDB is to run some code on all elements
that match a condition or are specified by their ID. This is
implemented in this function.
The function passed as ``func`` has to be a callable. It's first
argument will be the data currently in the database. It's second
argument is the element ID of the currently processed element.
See: :meth:`~.update`, :meth:`.remove`
:param func: the function to execute on every included element.
first argument: all data
second argument: the current eid
:param cond: elements to use, or
:param eids: elements to use
:returns: the element IDs that were affected during processed
"""
data = self._read()
if eids is not None:
# Processed element specified by id
for eid in eids:
func(data, eid)
else:
# Collect affected eids
eids = []
# Processed elements specified by condition
for eid in list(data):
if cond(data[eid]):
func(data, eid)
eids.append(eid)
self._write(data)
return eids
def clear_cache(self):
"""
Clear the query cache.
A simple helper that clears the internal query cache.
"""
self._query_cache.clear()
def _get_next_id(self):
"""
Increment the ID used the last time and return it
"""
current_id = self._last_id + 1
self._last_id = current_id
return current_id
def _read(self):
"""
Reading access to the DB.
:returns: all values
:rtype: dict
"""
return self._storage.read()
def _write(self, values):
"""
Writing access to the DB.
:param values: the new values to write
:type values: dict
"""
self._query_cache.clear()
self._storage.write(values)
def __len__(self):
"""
Get the total number of elements in the table.
"""
return len(self._read())
def all(self):
"""
Get all elements stored in the table.
:returns: a list with all elements.
:rtype: list[Element]
"""
return list(itervalues(self._read()))
def insert(self, element):
"""
Insert a new element into the table.
:param element: the element to insert
:returns: the inserted element's ID
"""
eid = self._get_next_id()
if not isinstance(element, dict):
raise ValueError('Element is not a dictionary')
data = self._read()
data[eid] = element
self._write(data)
return eid
def insert_multiple(self, elements):
"""
Insert multiple elements into the table.
:param elements: a list of elements to insert
:returns: a list containing the inserted elements' IDs
"""
eids = []
data = self._read()
for element in elements:
eid = self._get_next_id()
eids.append(eid)
data[eid] = element
self._write(data)
return eids
def remove(self, cond=None, eids=None):
"""
Remove all matching elements.
:param cond: the condition to check against
:type cond: query
:param eids: a list of element IDs
:type eids: list
:returns: a list containing the removed element's ID
"""
return self.process_elements(lambda data, eid: data.pop(eid), cond,
eids)
def update(self, fields, cond=None, eids=None):
"""
Update all matching elements to have a given set of fields.
:param fields: the fields that the matching elements will have
or a method that will update the elements
:type fields: dict | dict -> None
:param cond: which elements to update
:type cond: query
:param eids: a list of element IDs
:type eids: list
:returns: a list containing the updated element's ID
"""
if callable(fields):
return self.process_elements(lambda data, eid: fields(data[eid]),
cond, eids)
else:
return self.process_elements(
lambda data, eid: data[eid].update(fields), cond, eids)
def purge(self):
"""
Purge the table by removing all elements.
"""
self._write({})
self._last_id = 0
def search(self, cond):
"""
Search for all elements matching a 'where' cond.
:param cond: the condition to check against
:type cond: Query
:returns: list of matching elements
:rtype: list[Element]
"""
if cond in self._query_cache:
return self._query_cache[cond]
elements = [element for element in self.all() if cond(element)]
self._query_cache[cond] = elements
return elements
def get(self, cond=None, eid=None):
"""
Get exactly one element specified by a query or and ID.
Returns ``None`` if the element doesn't exist
:param cond: the condition to check against
:type cond: Query
:param eid: the element's ID
:returns: the element or None
:rtype: Element | None
"""
# Cannot use process_elements here because we want to return a
# specific element
if eid is not None:
# Element specified by ID
return self._read().get(eid, None)
# Element specified by condition
for element in self.all():
if cond(element):
return element
def count(self, cond):
"""
Count the elements matching a condition.
:param cond: the condition use
:type cond: Query
"""
return len(self.search(cond))
def contains(self, cond=None, eids=None):
"""
Check wether the database contains an element matching a condition or
an ID.
If ``eids`` is set, it checks if the db contains an element with one
of the specified.
:param cond: the condition use
:type cond: Query
:param eids: the element IDs to look for
"""
if eids is not None:
# Elements specified by ID
return any(self.get(eid=eid) for eid in eids)
# Element specified by condition
return self.get(cond) is not None
class Table(object):
"""
Represents a single TinyDB Table.
"""
def __init__(self, name, db, cache_size=10):
"""
Get access to a table.
:param name: The name of the table.
:type name: str
:param db: The parent database.
:type db: tinydb.database.TinyDB
:param cache_size: Maximum size of query cache.
"""
self.name = name
self._db = db
self._query_cache = LRUCache(capacity=cache_size)
old_ids = self._read().keys()
if old_ids:
self._last_id = max(i for i in old_ids)
else:
self._last_id = 0
def process_elements(self, func, cond=None, eids=None):
"""
Helper function for processing all elements specified by condition
or IDs.
A repeating pattern in TinyDB is to run some code on all elements
that match a condition or are specified by their ID. This is
implemented in this function.
The function passed as ``func`` has to be a callable. It's first
argument will be the data currently in the database. It's second
argument is the element ID of the currently processed element.
See: :meth:`~.update`, :meth:`.remove`
:param func: the function to execute on every included element.
first argument: all data
second argument: the current eid
:param cond: elements to use
:param eids: elements to use
"""
data = self._read()
if eids is not None:
# Processed element specified by id
for eid in eids:
func(data, eid)
else:
# Processed elements specified by condition
for eid in list(data):
if cond(data[eid]):
func(data, eid)
self._write(data)
def _get_next_id(self):
"""
Increment the ID used the last time and return it
"""
current_id = self._last_id + 1
self._last_id = current_id
return current_id
def _read(self):
"""
Reading access to the DB.
:returns: all values
:rtype: dict
"""
raw_data = self._db._read(self.name)
data = {}
for key in list(raw_data):
eid = int(key)
data[eid] = Element(raw_data[key], eid)
return data
def _write(self, values):
"""
Writing access to the DB.
:param values: the new values to write
:type values: dict
"""
self._query_cache.clear()
self._db._write(values, self.name)
def __len__(self):
"""
Get the total number of elements in the table.
"""
return len(self._read())
def all(self):
"""
Get all elements stored in the table.
:returns: a list with all elements.
:rtype: list[Element]
"""
return list(self._read().values())
def insert(self, element):
"""
Insert a new element into the table.
:param element: the element to insert
:returns: the inserted element's ID
"""
eid = self._get_next_id()
data = self._read()
data[eid] = element
self._write(data)
return eid
def insert_multiple(self, elements):
"""
Insert multiple elements into the table.
:param elements: a list of elements to insert
:returns: a list containing the inserted elements' IDs
"""
return [self.insert(element) for element in elements]
def remove(self, cond=None, eids=None):
"""
Remove all matching elements.
:param cond: the condition to check against
:type cond: query
:param eids: a list of element IDs
:type eids: list
"""
self.process_elements(lambda data, eid: data.pop(eid), cond, eids)
def update(self, fields, cond=None, eids=None):
"""
Update all matching elements to have a given set of fields.
:param fields: the fields that the matching elements will have
or a method that will update the elements
:type fields: dict | (dict, int) -> None
:param cond: which elements to update
:type cond: query
:param eids: a list of element IDs
:type eids: list
"""
if callable(fields):
_update = lambda data, eid: fields(data[eid])
else:
_update = lambda data, eid: data[eid].update(fields)
self.process_elements(_update, cond, eids)
def purge(self):
"""
Purge the table by removing all elements.
"""
self._write({})
self._last_id = 0
def search(self, cond):
"""
Search for all elements matching a 'where' cond.
:param cond: the condition to check against
:type cond: Query
:returns: list of matching elements
:rtype: list[Element]
"""
if cond in self._query_cache:
return self._query_cache[cond]
elements = [e for e in self.all() if cond(e)]
self._query_cache[cond] = elements
return elements
def get(self, cond=None, eid=None):
"""
Get exactly one element specified by a query or and ID.
Returns ``None`` if the element doesn't exist
:param cond: the condition to check against
:type cond: Query
:param eid: the element's ID
:returns: the element or None
:rtype: Element | None
"""
# Cannot use process_elements here because we want to return a
# specific element
if eid is not None:
# Element specified by ID
return self._read().get(eid, None)
# Element specified by condition
elements = self.search(cond)
if elements:
return elements[0]
def count(self, cond):
"""
Count the elements matching a condition.
:param cond: the condition use
:type cond: Query
"""
return len(self.search(cond))
def contains(self, cond=None, eids=None):
"""
Check wether the database contains an element matching a condition or
an ID.
If ``eids`` is set, it checks if the db contains an element with one
of the specified.
:param cond: the condition use
:type cond: Query
:param eids: the element IDs to look for
"""
if eids is not None:
# Elements specified by ID
return any(self.get(eid=eid) for eid in eids)
# Element specified by condition
return self.count(cond) > 0
def __enter__(self):
"""
Allow the database to be used as a context manager.
:return: the table instance
"""
return self
def __exit__(self, *args):
"""
Try to close the storage after being used as a context manager.
"""
_ = args
self._db._storage.close()
close = __exit__
class Table(object):
"""
Represents a single TinyDB Table.
"""
def __init__(self, storage, cache_size=10):
"""
Get access to a table.
:param storage: Access to the storage
:type storage: StorageProxyus
:param cache_size: Maximum size of query cache.
"""
self._storage = storage
self._query_cache = LRUCache(capacity=cache_size)
data = self._read()
if data:
self._last_id = max(i for i in data)
else:
self._last_id = 0
def process_elements(self, func, cond=None, eids=None):
"""
Helper function for processing all elements specified by condition
or IDs.
A repeating pattern in TinyDB is to run some code on all elements
that match a condition or are specified by their ID. This is
implemented in this function.
The function passed as ``func`` has to be a callable. It's first
argument will be the data currently in the database. It's second
argument is the element ID of the currently processed element.
See: :meth:`~.update`, :meth:`.remove`
:param func: the function to execute on every included element.
first argument: all data
second argument: the current eid
:param cond: elements to use, or
:param eids: elements to use
:returns: the element IDs that were affected during processed
"""
data = self._read()
if eids is not None:
# Processed element specified by id
for eid in eids:
func(data, eid)
else:
# Collect affected eids
eids = []
# Processed elements specified by condition
for eid in list(data):
if cond(data[eid]):
func(data, eid)
eids.append(eid)
self._write(data)
return eids
def clear_cache(self):
"""
Clear the query cache.
A simple helper that clears the internal query cache.
"""
self._query_cache.clear()
def _get_next_id(self):
"""
Increment the ID used the last time and return it
"""
current_id = self._last_id + 1
self._last_id = current_id
return current_id
def _read(self):
"""
Reading access to the DB.
:returns: all values
:rtype: dict
"""
return self._storage.read()
def _write(self, values):
"""
Writing access to the DB.
:param values: the new values to write
:type values: dict
"""
self._query_cache.clear()
self._storage.write(values)
def __len__(self):
"""
Get the total number of elements in the table.
"""
return len(self._read())
def all(self):
"""
Get all elements stored in the table.
:returns: a list with all elements.
:rtype: list[Element]
"""
return list(itervalues(self._read()))
def insert(self, element):
"""
Insert a new element into the table.
:param element: the element to insert
:returns: the inserted element's ID
"""
eid = self._get_next_id()
if not isinstance(element, dict):
raise ValueError("Element is not a dictionary")
data = self._read()
data[eid] = element
self._write(data)
return eid
def insert_multiple(self, elements):
"""
Insert multiple elements into the table.
:param elements: a list of elements to insert
:returns: a list containing the inserted elements' IDs
"""
eids = []
data = self._read()
for element in elements:
eid = self._get_next_id()
eids.append(eid)
data[eid] = element
self._write(data)
return eids
def remove(self, cond=None, eids=None):
"""
Remove all matching elements.
:param cond: the condition to check against
:type cond: query
:param eids: a list of element IDs
:type eids: list
:returns: a list containing the removed element's ID
"""
return self.process_elements(lambda data, eid: data.pop(eid), cond, eids)
def update(self, fields, cond=None, eids=None):
"""
Update all matching elements to have a given set of fields.
:param fields: the fields that the matching elements will have
or a method that will update the elements
:type fields: dict | dict -> None
:param cond: which elements to update
:type cond: query
:param eids: a list of element IDs
:type eids: list
:returns: a list containing the updated element's ID
"""
if callable(fields):
return self.process_elements(lambda data, eid: fields(data[eid]), cond, eids)
else:
return self.process_elements(lambda data, eid: data[eid].update(fields), cond, eids)
def purge(self):
"""
Purge the table by removing all elements.
"""
self._write({})
self._last_id = 0
def search(self, cond):
"""
Search for all elements matching a 'where' cond.
:param cond: the condition to check against
:type cond: Query
:returns: list of matching elements
:rtype: list[Element]
"""
if cond in self._query_cache:
return self._query_cache[cond]
elements = [element for element in self.all() if cond(element)]
self._query_cache[cond] = elements
return elements
def get(self, cond=None, eid=None):
"""
Get exactly one element specified by a query or and ID.
Returns ``None`` if the element doesn't exist
:param cond: the condition to check against
:type cond: Query
:param eid: the element's ID
:returns: the element or None
:rtype: Element | None
"""
# Cannot use process_elements here because we want to return a
# specific element
if eid is not None:
# Element specified by ID
return self._read().get(eid, None)
# Element specified by condition
for element in self.all():
if cond(element):
return element
def count(self, cond):
"""
Count the elements matching a condition.
:param cond: the condition use
:type cond: Query
"""
return len(self.search(cond))
def contains(self, cond=None, eids=None):
"""
Check wether the database contains an element matching a condition or
an ID.
If ``eids`` is set, it checks if the db contains an element with one
of the specified.
:param cond: the condition use
:type cond: Query
:param eids: the element IDs to look for
"""
if eids is not None:
# Elements specified by ID
return any(self.get(eid=eid) for eid in eids)
# Element specified by condition
return self.get(cond) is not None
