# Copyright DataStax, Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import copy from datetime import datetime, timedelta from functools import partial import time from warnings import warn from cassandra.query import SimpleStatement, BatchType as CBatchType, BatchStatement from cassandra.cqlengine import columns, CQLEngineException, ValidationError, UnicodeMixin from cassandra.cqlengine import connection as conn from cassandra.cqlengine.functions import Token, BaseQueryFunction, QueryValue from cassandra.cqlengine.operators import (InOperator, EqualsOperator, GreaterThanOperator, GreaterThanOrEqualOperator, LessThanOperator, LessThanOrEqualOperator, ContainsOperator, BaseWhereOperator) from cassandra.cqlengine.statements import (WhereClause, SelectStatement, DeleteStatement, UpdateStatement, InsertStatement, BaseCQLStatement, MapDeleteClause, ConditionalClause) class QueryException(CQLEngineException): pass class IfNotExistsWithCounterColumn(CQLEngineException): pass class IfExistsWithCounterColumn(CQLEngineException): pass class LWTException(CQLEngineException): """Lightweight conditional exception. This exception will be raised when a write using an `IF` clause could not be applied due to existing data violating the condition. The existing data is available through the ``existing`` attribute. :param existing: The current state of the data which prevented the write. """ def __init__(self, existing): super(LWTException, self).__init__("LWT Query was not applied") self.existing = existing class DoesNotExist(QueryException): pass class MultipleObjectsReturned(QueryException): pass def check_applied(result): """ Raises LWTException if it looks like a failed LWT request. A LWTException won't be raised in the special case in which there are several failed LWT in a :class:`~cqlengine.query.BatchQuery`. """ try: applied = result.was_applied except Exception: applied = True # result was not LWT form if not applied: raise LWTException(result.one()) class AbstractQueryableColumn(UnicodeMixin): """ exposes cql query operators through pythons builtin comparator symbols """ def _get_column(self): raise NotImplementedError def __unicode__(self): raise NotImplementedError def _to_database(self, val): if isinstance(val, QueryValue): return val else: return self._get_column().to_database(val) def in_(self, item): """ Returns an in operator used where you'd typically want to use python's `in` operator """ return WhereClause(str(self), InOperator(), item) def contains_(self, item): """ Returns a CONTAINS operator """ return WhereClause(str(self), ContainsOperator(), item) def __eq__(self, other): return WhereClause(str(self), EqualsOperator(), self._to_database(other)) def __gt__(self, other): return WhereClause(str(self), GreaterThanOperator(), self._to_database(other)) def __ge__(self, other): return WhereClause(str(self), GreaterThanOrEqualOperator(), self._to_database(other)) def __lt__(self, other): return WhereClause(str(self), LessThanOperator(), self._to_database(other)) def __le__(self, other): return WhereClause(str(self), LessThanOrEqualOperator(), self._to_database(other)) class BatchType(object): Unlogged = 'UNLOGGED' Counter = 'COUNTER' class BatchQuery(object): """ Handles the batching of queries http://docs.datastax.com/en/cql/3.0/cql/cql_reference/batch_r.html See :doc:`/cqlengine/batches` for more details. """ warn_multiple_exec = True _consistency = None _connection = None _connection_explicit = False def __init__(self, batch_type=None, timestamp=None, consistency=None, execute_on_exception=False, timeout=conn.NOT_SET, connection=None): """ :param batch_type: (optional) One of batch type values available through BatchType enum :type batch_type: BatchType, str or None :param timestamp: (optional) A datetime or timedelta object with desired timestamp to be applied to the batch conditional. :type timestamp: datetime or timedelta or None :param consistency: (optional) One of consistency values ("ANY", "ONE", "QUORUM" etc) :type consistency: The :class:`.ConsistencyLevel` to be used for the batch query, or None. :param execute_on_exception: (Defaults to False) Indicates that when the BatchQuery instance is used as a context manager the queries accumulated within the context must be executed despite encountering an error within the context. By default, any exception raised from within the context scope will cause the batched queries not to be executed. :type execute_on_exception: bool :param timeout: (optional) Timeout for the entire batch (in seconds), if not specified fallback to default session timeout :type timeout: float or None :param str connection: Connection name to use for the batch execution """ self.queries = [] self.batch_type = batch_type if timestamp is not None and not isinstance(timestamp, (datetime, timedelta)): raise CQLEngineException('timestamp object must be an instance of datetime') self.timestamp = timestamp self._consistency = consistency self._execute_on_exception = execute_on_exception self._timeout = timeout self._callbacks = [] self._executed = False self._context_entered = False self._connection = connection if connection: self._connection_explicit = True def add_query(self, query): if not isinstance(query, BaseCQLStatement): raise CQLEngineException('only BaseCQLStatements can be added to a batch query') self.queries.append(query) def consistency(self, consistency): self._consistency = consistency def _execute_callbacks(self): for callback, args, kwargs in self._callbacks: callback(*args, **kwargs) def add_callback(self, fn, *args, **kwargs): """Add a function and arguments to be passed to it to be executed after the batch executes. A batch can support multiple callbacks. Note, that if the batch does not execute, the callbacks are not executed. A callback, thus, is an "on batch success" handler. :param fn: Callable object :type fn: callable :param args: Positional arguments to be passed to the callback at the time of execution :param kwargs: Named arguments to be passed to the callback at the time of execution """ if not callable(fn): raise ValueError("Value for argument 'fn' is {0} and is not a callable object.".format(type(fn))) self._callbacks.append((fn, args, kwargs)) def execute(self): if self._executed and self.warn_multiple_exec: msg = "Batch executed multiple times." if self._context_entered: msg += " If using the batch as a context manager, there is no need to call execute directly." warn(msg) self._executed = True if len(self.queries) == 0: # Empty batch is a no-op # except for callbacks self._execute_callbacks() return batch_type = None if self.batch_type is CBatchType.LOGGED else self.batch_type opener = 'BEGIN ' + (str(batch_type) + ' ' if batch_type else '') + ' BATCH' if self.timestamp: if isinstance(self.timestamp, int): ts = self.timestamp elif isinstance(self.timestamp, (datetime, timedelta)): ts = self.timestamp if isinstance(self.timestamp, timedelta): ts += datetime.now() # Apply timedelta ts = int(time.mktime(ts.timetuple()) * 1e+6 + ts.microsecond) else: raise ValueError("Batch expects a long, a timedelta, or a datetime") opener += ' USING TIMESTAMP {0}'.format(ts) query_list = [opener] parameters = {} ctx_counter = 0 for query in self.queries: query.update_context_id(ctx_counter) ctx = query.get_context() ctx_counter += len(ctx) query_list.append(' ' + str(query)) parameters.update(ctx) query_list.append('APPLY BATCH;') tmp = conn.execute('\n'.join(query_list), parameters, self._consistency, self._timeout, connection=self._connection) check_applied(tmp) self.queries = [] self._execute_callbacks() def __enter__(self): self._context_entered = True return self def __exit__(self, exc_type, exc_val, exc_tb): # don't execute if there was an exception by default if exc_type is not None and not self._execute_on_exception: return self.execute() class ContextQuery(object): """ A Context manager to allow a Model to switch context easily. Presently, the context only specifies a keyspace for model IO. :param args: One or more models. A model should be a class type, not an instance. :param kwargs: (optional) Context parameters: can be *keyspace* or *connection* For example: .. code-block:: python with ContextQuery(Automobile, keyspace='test2') as A: A.objects.create(manufacturer='honda', year=2008, model='civic') print(len(A.objects.all())) # 1 result with ContextQuery(Automobile, keyspace='test4') as A: print(len(A.objects.all())) # 0 result # Multiple models with ContextQuery(Automobile, Automobile2, connection='cluster2') as (A, A2): print(len(A.objects.all())) print(len(A2.objects.all())) """ def __init__(self, *args, **kwargs): from cassandra.cqlengine import models self.models = [] if len(args) < 1: raise ValueError("No model provided.") keyspace = kwargs.pop('keyspace', None) connection = kwargs.pop('connection', None) if kwargs: raise ValueError("Unknown keyword argument(s): {0}".format( ','.join(kwargs.keys()))) for model in args: try: issubclass(model, models.Model) except TypeError: raise ValueError("Models must be derived from base Model.") m = models._clone_model_class(model, {}) if keyspace: m.__keyspace__ = keyspace if connection: m.__connection__ = connection self.models.append(m) def __enter__(self): if len(self.models) > 1: return tuple(self.models) return self.models[0] def __exit__(self, exc_type, exc_val, exc_tb): return class AbstractQuerySet(object): def __init__(self, model): super(AbstractQuerySet, self).__init__() self.model = model # Where clause filters self._where = [] # Conditional clause filters self._conditional = [] # ordering arguments self._order = [] self._allow_filtering = False # CQL has a default limit of 10000, it's defined here # because explicit is better than implicit self._limit = 10000 # We store the fields for which we use the Equal operator # in a query, so we don't select it from the DB. _defer_fields # will contain the names of the fields in the DB, not the names # of the variables used by the mapper self._defer_fields = set() self._deferred_values = {} # This variable will hold the names in the database of the fields # for which we want to query self._only_fields = [] self._values_list = False self._flat_values_list = False # results cache self._result_cache = None self._result_idx = None self._result_generator = None self._materialize_results = True self._distinct_fields = None self._count = None self._batch = None self._ttl = None self._consistency = None self._timestamp = None self._if_not_exists = False self._timeout = conn.NOT_SET self._if_exists = False self._fetch_size = None self._connection = None @property def column_family_name(self): return self.model.column_family_name() def _execute(self, statement): if self._batch: return self._batch.add_query(statement) else: connection = self._connection or self.model._get_connection() result = _execute_statement(self.model, statement, self._consistency, self._timeout, connection=connection) if self._if_not_exists or self._if_exists or self._conditional: check_applied(result) return result def __unicode__(self): return str(self._select_query()) def __str__(self): return str(self.__unicode__()) def __call__(self, *args, **kwargs): return self.filter(*args, **kwargs) def __deepcopy__(self, memo): clone = self.__class__(self.model) for k, v in self.__dict__.items(): if k in ['_con', '_cur', '_result_cache', '_result_idx', '_result_generator', '_construct_result']: # don't clone these, which are per-request-execution clone.__dict__[k] = None elif k == '_batch': # we need to keep the same batch instance across # all queryset clones, otherwise the batched queries # fly off into other batch instances which are never # executed, thx @dokai clone.__dict__[k] = self._batch elif k == '_timeout': clone.__dict__[k] = self._timeout else: clone.__dict__[k] = copy.deepcopy(v, memo) return clone def __len__(self): self._execute_query() return self.count() # ----query generation / execution---- def _select_fields(self): """ returns the fields to select """ return [] def _validate_select_where(self): """ put select query validation here """ def _select_query(self): """ Returns a select clause based on the given filter args """ if self._where: self._validate_select_where() return SelectStatement( self.column_family_name, fields=self._select_fields(), where=self._where, order_by=self._order, limit=self._limit, allow_filtering=self._allow_filtering, distinct_fields=self._distinct_fields, fetch_size=self._fetch_size ) # ----Reads------ def _execute_query(self): if self._batch: raise CQLEngineException("Only inserts, updates, and deletes are available in batch mode") if self._result_cache is None: self._result_generator = (i for i in self._execute(self._select_query())) self._result_cache = [] self._construct_result = self._maybe_inject_deferred(self._get_result_constructor()) # "DISTINCT COUNT()" is not supported in C* < 2.2, so we need to materialize all results to get # len() and count() working with DISTINCT queries if self._materialize_results or self._distinct_fields: self._fill_result_cache() def _fill_result_cache(self): """ Fill the result cache with all results. """ idx = 0 try: while True: idx += 1000 self._fill_result_cache_to_idx(idx) except StopIteration: pass self._count = len(self._result_cache) def _fill_result_cache_to_idx(self, idx): self._execute_query() if self._result_idx is None: self._result_idx = -1 qty = idx - self._result_idx if qty < 1: return else: for idx in range(qty): self._result_idx += 1 while True: try: self._result_cache[self._result_idx] = self._construct_result(self._result_cache[self._result_idx]) break except IndexError: self._result_cache.append(next(self._result_generator)) def __iter__(self): self._execute_query() idx = 0 while True: if len(self._result_cache) <= idx: try: self._result_cache.append(next(self._result_generator)) except StopIteration: break instance = self._result_cache[idx] if isinstance(instance, dict): self._fill_result_cache_to_idx(idx) yield self._result_cache[idx] idx += 1 def __getitem__(self, s): self._execute_query() if isinstance(s, slice): start = s.start if s.start else 0 if start < 0 or (s.stop is not None and s.stop < 0): warn("ModelQuerySet slicing with negative indices support will be removed in 4.0.", DeprecationWarning) # calculate the amount of results that need to be loaded end = s.stop if start < 0 or s.stop is None or s.stop < 0: end = self.count() try: self._fill_result_cache_to_idx(end) except StopIteration: pass return self._result_cache[start:s.stop:s.step] else: try: s = int(s) except (ValueError, TypeError): raise TypeError('QuerySet indices must be integers') if s < 0: warn("ModelQuerySet indexing with negative indices support will be removed in 4.0.", DeprecationWarning) # Using negative indexing is costly since we have to execute a count() if s < 0: num_results = self.count() s += num_results try: self._fill_result_cache_to_idx(s) except StopIteration: raise IndexError return self._result_cache[s] def _get_result_constructor(self): """ Returns a function that will be used to instantiate query results """ raise NotImplementedError @staticmethod def _construct_with_deferred(f, deferred, row): row.update(deferred) return f(row) def _maybe_inject_deferred(self, constructor): return partial(self._construct_with_deferred, constructor, self._deferred_values)\ if self._deferred_values else constructor def batch(self, batch_obj): """ Set a batch object to run the query on. Note: running a select query with a batch object will raise an exception """ if self._connection: raise CQLEngineException("Cannot specify the connection on model in batch mode.") if batch_obj is not None and not isinstance(batch_obj, BatchQuery): raise CQLEngineException('batch_obj must be a BatchQuery instance or None') clone = copy.deepcopy(self) clone._batch = batch_obj return clone def first(self): try: return next(iter(self)) except StopIteration: return None def all(self): """ Returns a queryset matching all rows .. code-block:: python for user in User.objects().all(): print(user) """ return copy.deepcopy(self) def consistency(self, consistency): """ Sets the consistency level for the operation. See :class:`.ConsistencyLevel`. .. code-block:: python for user in User.objects(id=3).consistency(CL.ONE): print(user) """ clone = copy.deepcopy(self) clone._consistency = consistency return clone def _parse_filter_arg(self, arg): """ Parses a filter arg in the format: __ :returns: colname, op tuple """ statement = arg.rsplit('__', 1) if len(statement) == 1: return arg, None elif len(statement) == 2: return (statement[0], statement[1]) if arg != 'pk__token' else (arg, None) else: raise QueryException("Can't parse '{0}'".format(arg)) def iff(self, *args, **kwargs): """Adds IF statements to queryset""" if len([x for x in kwargs.values() if x is None]): raise CQLEngineException("None values on iff are not allowed") clone = copy.deepcopy(self) for operator in args: if not isinstance(operator, ConditionalClause): raise QueryException('{0} is not a valid query operator'.format(operator)) clone._conditional.append(operator) for arg, val in kwargs.items(): if isinstance(val, Token): raise QueryException("Token() values are not valid in conditionals") col_name, col_op = self._parse_filter_arg(arg) try: column = self.model._get_column(col_name) except KeyError: raise QueryException("Can't resolve column name: '{0}'".format(col_name)) if isinstance(val, BaseQueryFunction): query_val = val else: query_val = column.to_database(val) operator_class = BaseWhereOperator.get_operator(col_op or 'EQ') operator = operator_class() clone._conditional.append(WhereClause(column.db_field_name, operator, query_val)) return clone def filter(self, *args, **kwargs): """ Adds WHERE arguments to the queryset, returning a new queryset See :ref:`retrieving-objects-with-filters` Returns a QuerySet filtered on the keyword arguments """ # add arguments to the where clause filters if len([x for x in kwargs.values() if x is None]): raise CQLEngineException("None values on filter are not allowed") clone = copy.deepcopy(self) for operator in args: if not isinstance(operator, WhereClause): raise QueryException('{0} is not a valid query operator'.format(operator)) clone._where.append(operator) for arg, val in kwargs.items(): col_name, col_op = self._parse_filter_arg(arg) quote_field = True if not isinstance(val, Token): try: column = self.model._get_column(col_name) except KeyError: raise QueryException("Can't resolve column name: '{0}'".format(col_name)) else: if col_name != 'pk__token': raise QueryException("Token() values may only be compared to the 'pk__token' virtual column") column = columns._PartitionKeysToken(self.model) quote_field = False partition_columns = column.partition_columns if len(partition_columns) != len(val.value): raise QueryException( 'Token() received {0} arguments but model has {1} partition keys'.format( len(val.value), len(partition_columns))) val.set_columns(partition_columns) # get query operator, or use equals if not supplied operator_class = BaseWhereOperator.get_operator(col_op or 'EQ') operator = operator_class() if isinstance(operator, InOperator): if not isinstance(val, (list, tuple)): raise QueryException('IN queries must use a list/tuple value') query_val = [column.to_database(v) for v in val] elif isinstance(val, BaseQueryFunction): query_val = val elif (isinstance(operator, ContainsOperator) and isinstance(column, (columns.List, columns.Set, columns.Map))): # For ContainsOperator and collections, we query using the value, not the container query_val = val else: query_val = column.to_database(val) if not col_op: # only equal values should be deferred clone._defer_fields.add(column.db_field_name) clone._deferred_values[column.db_field_name] = val # map by db field name for substitution in results clone._where.append(WhereClause(column.db_field_name, operator, query_val, quote_field=quote_field)) return clone def get(self, *args, **kwargs): """ Returns a single instance matching this query, optionally with additional filter kwargs. See :ref:`retrieving-objects-with-filters` Returns a single object matching the QuerySet. .. code-block:: python user = User.get(id=1) If no objects are matched, a :class:`~.DoesNotExist` exception is raised. If more than one object is found, a :class:`~.MultipleObjectsReturned` exception is raised. """ if args or kwargs: return self.filter(*args, **kwargs).get() self._execute_query() # Check that the resultset only contains one element, avoiding sending a COUNT query try: self[1] raise self.model.MultipleObjectsReturned('Multiple objects found') except IndexError: pass try: obj = self[0] except IndexError: raise self.model.DoesNotExist return obj def _get_ordering_condition(self, colname): order_type = 'DESC' if colname.startswith('-') else 'ASC' colname = colname.replace('-', '') return colname, order_type def order_by(self, *colnames): """ Sets the column(s) to be used for ordering Default order is ascending, prepend a '-' to any column name for descending *Note: column names must be a clustering key* .. code-block:: python from uuid import uuid1,uuid4 class Comment(Model): photo_id = UUID(primary_key=True) comment_id = TimeUUID(primary_key=True, default=uuid1) # second primary key component is a clustering key comment = Text() sync_table(Comment) u = uuid4() for x in range(5): Comment.create(photo_id=u, comment="test %d" % x) print("Normal") for comment in Comment.objects(photo_id=u): print(comment.comment_id) print("Reversed") for comment in Comment.objects(photo_id=u).order_by("-comment_id"): print(comment.comment_id) """ if len(colnames) == 0: clone = copy.deepcopy(self) clone._order = [] return clone conditions = [] for colname in colnames: conditions.append('"{0}" {1}'.format(*self._get_ordering_condition(colname))) clone = copy.deepcopy(self) clone._order.extend(conditions) return clone def count(self): """ Returns the number of rows matched by this query. *Note: This function executes a SELECT COUNT() and has a performance cost on large datasets* """ if self._batch: raise CQLEngineException("Only inserts, updates, and deletes are available in batch mode") if self._count is None: query = self._select_query() query.count = True result = self._execute(query) count_row = result.one().popitem() self._count = count_row[1] return self._count def distinct(self, distinct_fields=None): """ Returns the DISTINCT rows matched by this query. distinct_fields default to the partition key fields if not specified. *Note: distinct_fields must be a partition key or a static column* .. code-block:: python class Automobile(Model): manufacturer = columns.Text(partition_key=True) year = columns.Integer(primary_key=True) model = columns.Text(primary_key=True) price = columns.Decimal() sync_table(Automobile) # create rows Automobile.objects.distinct() # or Automobile.objects.distinct(['manufacturer']) """ clone = copy.deepcopy(self) if distinct_fields: clone._distinct_fields = distinct_fields else: clone._distinct_fields = [x.column_name for x in self.model._partition_keys.values()] return clone def limit(self, v): """ Limits the number of results returned by Cassandra. Use *0* or *None* to disable. *Note that CQL's default limit is 10,000, so all queries without a limit set explicitly will have an implicit limit of 10,000* .. code-block:: python # Fetch 100 users for user in User.objects().limit(100): print(user) # Fetch all users for user in User.objects().limit(None): print(user) """ if v is None: v = 0 if not isinstance(v, int): raise TypeError if v == self._limit: return self if v < 0: raise QueryException("Negative limit is not allowed") clone = copy.deepcopy(self) clone._limit = v return clone def fetch_size(self, v): """ Sets the number of rows that are fetched at a time. *Note that driver's default fetch size is 5000.* .. code-block:: python for user in User.objects().fetch_size(500): print(user) """ if not isinstance(v, int): raise TypeError if v == self._fetch_size: return self if v < 1: raise QueryException("fetch size less than 1 is not allowed") clone = copy.deepcopy(self) clone._fetch_size = v return clone def allow_filtering(self): """ Enables the (usually) unwise practive of querying on a clustering key without also defining a partition key """ clone = copy.deepcopy(self) clone._allow_filtering = True return clone def _only_or_defer(self, action, fields): if action == 'only' and self._only_fields: raise QueryException("QuerySet already has 'only' fields defined") clone = copy.deepcopy(self) # check for strange fields missing_fields = [f for f in fields if f not in self.model._columns.keys()] if missing_fields: raise QueryException( "Can't resolve fields {0} in {1}".format( ', '.join(missing_fields), self.model.__name__)) fields = [self.model._columns[field].db_field_name for field in fields] if action == 'defer': clone._defer_fields.update(fields) elif action == 'only': clone._only_fields = fields else: raise ValueError return clone def only(self, fields): """ Load only these fields for the returned query """ return self._only_or_defer('only', fields) def defer(self, fields): """ Don't load these fields for the returned query """ return self._only_or_defer('defer', fields) def create(self, **kwargs): return self.model(**kwargs) \ .batch(self._batch) \ .ttl(self._ttl) \ .consistency(self._consistency) \ .if_not_exists(self._if_not_exists) \ .timestamp(self._timestamp) \ .if_exists(self._if_exists) \ .using(connection=self._connection) \ .save() def delete(self): """ Deletes the contents of a query """ # validate where clause partition_keys = set(x.db_field_name for x in self.model._partition_keys.values()) if partition_keys - set(c.field for c in self._where): raise QueryException("The partition key must be defined on delete queries") dq = DeleteStatement( self.column_family_name, where=self._where, timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists ) self._execute(dq) def __eq__(self, q): if len(self._where) == len(q._where): return all([w in q._where for w in self._where]) return False def __ne__(self, q): return not (self != q) def timeout(self, timeout): """ :param timeout: Timeout for the query (in seconds) :type timeout: float or None """ clone = copy.deepcopy(self) clone._timeout = timeout return clone def using(self, keyspace=None, connection=None): """ Change the context on-the-fly of the Model class (keyspace, connection) """ if connection and self._batch: raise CQLEngineException("Cannot specify a connection on model in batch mode.") clone = copy.deepcopy(self) if keyspace: from cassandra.cqlengine.models import _clone_model_class clone.model = _clone_model_class(self.model, {'__keyspace__': keyspace}) if connection: clone._connection = connection return clone class ResultObject(dict): """ adds attribute access to a dictionary """ def __getattr__(self, item): try: return self[item] except KeyError: raise AttributeError class SimpleQuerySet(AbstractQuerySet): """ Overrides _get_result_constructor for querysets that do not define a model (e.g. NamedTable queries) """ def _get_result_constructor(self): """ Returns a function that will be used to instantiate query results """ return ResultObject class ModelQuerySet(AbstractQuerySet): """ """ def _validate_select_where(self): """ Checks that a filterset will not create invalid select statement """ # check that there's either a =, a IN or a CONTAINS (collection) # relationship with a primary key or indexed field. We also allow # custom indexes to be queried with any operator (a difference # between a secondary index) equal_ops = [self.model._get_column_by_db_name(w.field) \ for w in self._where if not isinstance(w.value, Token) and (isinstance(w.operator, EqualsOperator) or self.model._get_column_by_db_name(w.field).custom_index)] token_comparison = any([w for w in self._where if isinstance(w.value, Token)]) if not any(w.primary_key or w.has_index for w in equal_ops) and not token_comparison and not self._allow_filtering: raise QueryException( ('Where clauses require either =, a IN or a CONTAINS ' '(collection) comparison with either a primary key or ' 'indexed field. You might want to consider setting ' 'custom_index on fields that you manage index outside ' 'cqlengine.')) if not self._allow_filtering: # if the query is not on an indexed field if not any(w.has_index for w in equal_ops): if not any([w.partition_key for w in equal_ops]) and not token_comparison: raise QueryException( ('Filtering on a clustering key without a partition ' 'key is not allowed unless allow_filtering() is ' 'called on the queryset. You might want to consider ' 'setting custom_index on fields that you manage ' 'index outside cqlengine.')) def _select_fields(self): if self._defer_fields or self._only_fields: fields = [columns.db_field_name for columns in self.model._columns.values()] if self._defer_fields: fields = [f for f in fields if f not in self._defer_fields] # select the partition keys if all model fields are set defer if not fields: fields = [columns.db_field_name for columns in self.model._partition_keys.values()] if self._only_fields: fields = [f for f in fields if f in self._only_fields] if not fields: raise QueryException('No fields in select query. Only fields: "{0}", defer fields: "{1}"'.format( ','.join(self._only_fields), ','.join(self._defer_fields))) return fields return super(ModelQuerySet, self)._select_fields() def _get_result_constructor(self): """ Returns a function that will be used to instantiate query results """ if not self._values_list: # we want models return self.model._construct_instance elif self._flat_values_list: # the user has requested flattened list (1 value per row) key = self._only_fields[0] return lambda row: row[key] else: return lambda row: [row[f] for f in self._only_fields] def _get_ordering_condition(self, colname): colname, order_type = super(ModelQuerySet, self)._get_ordering_condition(colname) column = self.model._columns.get(colname) if column is None: raise QueryException("Can't resolve the column name: '{0}'".format(colname)) # validate the column selection if not column.primary_key: raise QueryException( "Can't order on '{0}', can only order on (clustered) primary keys".format(colname)) pks = [v for k, v in self.model._columns.items() if v.primary_key] if column == pks[0]: raise QueryException( "Can't order by the first primary key (partition key), clustering (secondary) keys only") return column.db_field_name, order_type def values_list(self, *fields, **kwargs): """ Instructs the query set to return tuples, not model instance """ flat = kwargs.pop('flat', False) if kwargs: raise TypeError('Unexpected keyword arguments to values_list: %s' % (kwargs.keys(),)) if flat and len(fields) > 1: raise TypeError("'flat' is not valid when values_list is called with more than one field.") clone = self.only(fields) clone._values_list = True clone._flat_values_list = flat return clone def ttl(self, ttl): """ Sets the ttl (in seconds) for modified data. *Note that running a select query with a ttl value will raise an exception* """ clone = copy.deepcopy(self) clone._ttl = ttl return clone def timestamp(self, timestamp): """ Allows for custom timestamps to be saved with the record. """ clone = copy.deepcopy(self) clone._timestamp = timestamp return clone def if_not_exists(self): """ Check the existence of an object before insertion. If the insertion isn't applied, a LWTException is raised. """ if self.model._has_counter: raise IfNotExistsWithCounterColumn('if_not_exists cannot be used with tables containing counter columns') clone = copy.deepcopy(self) clone._if_not_exists = True return clone def if_exists(self): """ Check the existence of an object before an update or delete. If the update or delete isn't applied, a LWTException is raised. """ if self.model._has_counter: raise IfExistsWithCounterColumn('if_exists cannot be used with tables containing counter columns') clone = copy.deepcopy(self) clone._if_exists = True return clone def update(self, **values): """ Performs an update on the row selected by the queryset. Include values to update in the update like so: .. code-block:: python Model.objects(key=n).update(value='x') Passing in updates for columns which are not part of the model will raise a ValidationError. Per column validation will be performed, but instance level validation will not (i.e., `Model.validate` is not called). This is sometimes referred to as a blind update. For example: .. code-block:: python class User(Model): id = Integer(primary_key=True) name = Text() setup(["localhost"], "test") sync_table(User) u = User.create(id=1, name="jon") User.objects(id=1).update(name="Steve") # sets name to null User.objects(id=1).update(name=None) Also supported is blindly adding and removing elements from container columns, without loading a model instance from Cassandra. Using the syntax `.update(column_name={x, y, z})` will overwrite the contents of the container, like updating a non container column. However, adding `__` to the end of the keyword arg, makes the update call add or remove items from the collection, without overwriting then entire column. Given the model below, here are the operations that can be performed on the different container columns: .. code-block:: python class Row(Model): row_id = columns.Integer(primary_key=True) set_column = columns.Set(Integer) list_column = columns.List(Integer) map_column = columns.Map(Integer, Integer) :class:`~cqlengine.columns.Set` - `add`: adds the elements of the given set to the column - `remove`: removes the elements of the given set to the column .. code-block:: python # add elements to a set Row.objects(row_id=5).update(set_column__add={6}) # remove elements to a set Row.objects(row_id=5).update(set_column__remove={4}) :class:`~cqlengine.columns.List` - `append`: appends the elements of the given list to the end of the column - `prepend`: prepends the elements of the given list to the beginning of the column .. code-block:: python # append items to a list Row.objects(row_id=5).update(list_column__append=[6, 7]) # prepend items to a list Row.objects(row_id=5).update(list_column__prepend=[1, 2]) :class:`~cqlengine.columns.Map` - `update`: adds the given keys/values to the columns, creating new entries if they didn't exist, and overwriting old ones if they did .. code-block:: python # add items to a map Row.objects(row_id=5).update(map_column__update={1: 2, 3: 4}) # remove items from a map Row.objects(row_id=5).update(map_column__remove={1, 2}) """ if not values: return nulled_columns = set() updated_columns = set() us = UpdateStatement(self.column_family_name, where=self._where, ttl=self._ttl, timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists) for name, val in values.items(): col_name, col_op = self._parse_filter_arg(name) col = self.model._columns.get(col_name) # check for nonexistant columns if col is None: raise ValidationError("{0}.{1} has no column named: {2}".format(self.__module__, self.model.__name__, col_name)) # check for primary key update attempts if col.is_primary_key: raise ValidationError("Cannot apply update to primary key '{0}' for {1}.{2}".format(col_name, self.__module__, self.model.__name__)) if col_op == 'remove' and isinstance(col, columns.Map): if not isinstance(val, set): raise ValidationError( "Cannot apply update operation '{0}' on column '{1}' with value '{2}'. A set is required.".format(col_op, col_name, val)) val = {v: None for v in val} else: # we should not provide default values in this use case. val = col.validate(val) if val is None: nulled_columns.add(col_name) continue us.add_update(col, val, operation=col_op) updated_columns.add(col_name) if us.assignments: self._execute(us) if nulled_columns: delete_conditional = [condition for condition in self._conditional if condition.field not in updated_columns] if self._conditional else None ds = DeleteStatement(self.column_family_name, fields=nulled_columns, where=self._where, conditionals=delete_conditional, if_exists=self._if_exists) self._execute(ds) class DMLQuery(object): """ A query object used for queries performing inserts, updates, or deletes this is usually instantiated by the model instance to be modified unlike the read query object, this is mutable """ _ttl = None _consistency = None _timestamp = None _if_not_exists = False _if_exists = False def __init__(self, model, instance=None, batch=None, ttl=None, consistency=None, timestamp=None, if_not_exists=False, conditional=None, timeout=conn.NOT_SET, if_exists=False): self.model = model self.column_family_name = self.model.column_family_name() self.instance = instance self._batch = batch self._ttl = ttl self._consistency = consistency self._timestamp = timestamp self._if_not_exists = if_not_exists self._if_exists = if_exists self._conditional = conditional self._timeout = timeout def _execute(self, statement): connection = self.instance._get_connection() if self.instance else self.model._get_connection() if self._batch: if self._batch._connection: if not self._batch._connection_explicit and connection and \ connection != self._batch._connection: raise CQLEngineException('BatchQuery queries must be executed on the same connection') else: # set the BatchQuery connection from the model self._batch._connection = connection return self._batch.add_query(statement) else: results = _execute_statement(self.model, statement, self._consistency, self._timeout, connection=connection) if self._if_not_exists or self._if_exists or self._conditional: check_applied(results) return results def batch(self, batch_obj): if batch_obj is not None and not isinstance(batch_obj, BatchQuery): raise CQLEngineException('batch_obj must be a BatchQuery instance or None') self._batch = batch_obj return self def _delete_null_columns(self, conditionals=None): """ executes a delete query to remove columns that have changed to null """ ds = DeleteStatement(self.column_family_name, conditionals=conditionals, if_exists=self._if_exists) deleted_fields = False static_only = True for _, v in self.instance._values.items(): col = v.column if v.deleted: ds.add_field(col.db_field_name) deleted_fields = True static_only &= col.static elif isinstance(col, columns.Map): uc = MapDeleteClause(col.db_field_name, v.value, v.previous_value) if uc.get_context_size() > 0: ds.add_field(uc) deleted_fields = True static_only |= col.static if deleted_fields: keys = self.model._partition_keys if static_only else self.model._primary_keys for name, col in keys.items(): ds.add_where(col, EqualsOperator(), getattr(self.instance, name)) self._execute(ds) def update(self): """ updates a row. This is a blind update call. All validation and cleaning needs to happen prior to calling this. """ if self.instance is None: raise CQLEngineException("DML Query intance attribute is None") assert type(self.instance) == self.model null_clustering_key = False if len(self.instance._clustering_keys) == 0 else True static_changed_only = True statement = UpdateStatement(self.column_family_name, ttl=self._ttl, timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists) for name, col in self.instance._clustering_keys.items(): null_clustering_key = null_clustering_key and col._val_is_null(getattr(self.instance, name, None)) updated_columns = set() # get defined fields and their column names for name, col in self.model._columns.items(): # if clustering key is null, don't include non static columns if null_clustering_key and not col.static and not col.partition_key: continue if not col.is_primary_key: val = getattr(self.instance, name, None) val_mgr = self.instance._values[name] if val is None: continue if not val_mgr.changed and not isinstance(col, columns.Counter): continue static_changed_only = static_changed_only and col.static statement.add_update(col, val, previous=val_mgr.previous_value) updated_columns.add(col.db_field_name) if statement.assignments: for name, col in self.model._primary_keys.items(): # only include clustering key if clustering key is not null, and non static columns are changed to avoid cql error if (null_clustering_key or static_changed_only) and (not col.partition_key): continue statement.add_where(col, EqualsOperator(), getattr(self.instance, name)) self._execute(statement) if not null_clustering_key: # remove conditions on fields that have been updated delete_conditionals = [condition for condition in self._conditional if condition.field not in updated_columns] if self._conditional else None self._delete_null_columns(delete_conditionals) def save(self): """ Creates / updates a row. This is a blind insert call. All validation and cleaning needs to happen prior to calling this. """ if self.instance is None: raise CQLEngineException("DML Query intance attribute is None") assert type(self.instance) == self.model nulled_fields = set() if self.instance._has_counter or self.instance._can_update(): if self.instance._has_counter: warn("'create' and 'save' actions on Counters are deprecated. It will be disallowed in 4.0. " "Use the 'update' mechanism instead.", DeprecationWarning) return self.update() else: insert = InsertStatement(self.column_family_name, ttl=self._ttl, timestamp=self._timestamp, if_not_exists=self._if_not_exists) static_save_only = False if len(self.instance._clustering_keys) == 0 else True for name, col in self.instance._clustering_keys.items(): static_save_only = static_save_only and col._val_is_null(getattr(self.instance, name, None)) for name, col in self.instance._columns.items(): if static_save_only and not col.static and not col.partition_key: continue val = getattr(self.instance, name, None) if col._val_is_null(val): if self.instance._values[name].changed: nulled_fields.add(col.db_field_name) continue if col.has_default and not self.instance._values[name].changed: # Ensure default columns included in a save() are marked as explicit, to get them *persisted* properly self.instance._values[name].explicit = True insert.add_assignment(col, getattr(self.instance, name, None)) # skip query execution if it's empty # caused by pointless update queries if not insert.is_empty: self._execute(insert) # delete any nulled columns if not static_save_only: self._delete_null_columns() def delete(self): """ Deletes one instance """ if self.instance is None: raise CQLEngineException("DML Query instance attribute is None") ds = DeleteStatement(self.column_family_name, timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists) for name, col in self.model._primary_keys.items(): val = getattr(self.instance, name) if val is None and not col.partition_key: continue ds.add_where(col, EqualsOperator(), val) self._execute(ds) def _execute_statement(model, statement, consistency_level, timeout, connection=None): params = statement.get_context() s = SimpleStatement(str(statement), consistency_level=consistency_level, fetch_size=statement.fetch_size) if model._partition_key_index: key_values = statement.partition_key_values(model._partition_key_index) if not any(v is None for v in key_values): parts = model._routing_key_from_values(key_values, conn.get_cluster(connection).protocol_version) s.routing_key = parts s.keyspace = model._get_keyspace() connection = connection or model._get_connection() return conn.execute(s, params, timeout=timeout, connection=connection)