boto3.dynamodb.conditions - Boto3 1.34.74 documentation

Publish date: 2024-05-03
 # Copyright 2015 Amazon.com, Inc. or its affiliates. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"). You # may not use this file except in compliance with the License. A copy of # the License is located at # # https://aws.amazon.com/apache2.0/ # # or in the "license" file accompanying this file. This file 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 re from collections import namedtuple from boto3.exceptions import ( DynamoDBNeedsConditionError, DynamoDBNeedsKeyConditionError, DynamoDBOperationNotSupportedError, ) ATTR_NAME_REGEX = re.compile(r'[^.\[\]]+(?![^\[]*\])') class ConditionBase: expression_format = '' expression_operator = '' has_grouped_values = False def __init__(self, *values): self._values = values def __and__(self, other): if not isinstance(other, ConditionBase): raise DynamoDBOperationNotSupportedError('AND', other) return And(self, other) def __or__(self, other): if not isinstance(other, ConditionBase): raise DynamoDBOperationNotSupportedError('OR', other) return Or(self, other) def __invert__(self): return Not(self) def get_expression(self): return { 'format': self.expression_format, 'operator': self.expression_operator, 'values': self._values, } def __eq__(self, other): if isinstance(other, type(self)): if self._values == other._values: return True return False def __ne__(self, other): return not self.__eq__(other) class AttributeBase: def __init__(self, name): self.name = name def __and__(self, value): raise DynamoDBOperationNotSupportedError('AND', self) def __or__(self, value): raise DynamoDBOperationNotSupportedError('OR', self) def __invert__(self): raise DynamoDBOperationNotSupportedError('NOT', self) def eq(self, value):  """Creates a condition where the attribute is equal to the value.  :param value: The value that the attribute is equal to.  """ return Equals(self, value) def lt(self, value):  """Creates a condition where the attribute is less than the value.  :param value: The value that the attribute is less than.  """ return LessThan(self, value) def lte(self, value):  """Creates a condition where the attribute is less than or equal to the  value.  :param value: The value that the attribute is less than or equal to.  """ return LessThanEquals(self, value) def gt(self, value):  """Creates a condition where the attribute is greater than the value.  :param value: The value that the attribute is greater than.  """ return GreaterThan(self, value) def gte(self, value):  """Creates a condition where the attribute is greater than or equal to  the value.  :param value: The value that the attribute is greater than or equal to.  """ return GreaterThanEquals(self, value) def begins_with(self, value):  """Creates a condition where the attribute begins with the value.  :param value: The value that the attribute begins with.  """ return BeginsWith(self, value) def between(self, low_value, high_value):  """Creates a condition where the attribute is greater than or equal  to the low value and less than or equal to the high value.  :param low_value: The value that the attribute is greater than or equal to.  :param high_value: The value that the attribute is less than or equal to.  """ return Between(self, low_value, high_value) def __eq__(self, other): return isinstance(other, type(self)) and self.name == other.name def __ne__(self, other): return not self.__eq__(other) class ConditionAttributeBase(ConditionBase, AttributeBase):  """This base class is for conditions that can have attribute methods.  One example is the Size condition. To complete a condition, you need  to apply another AttributeBase method like eq().  """ def __init__(self, *values): ConditionBase.__init__(self, *values) # This is assuming the first value to the condition is the attribute # in which can be used to generate its attribute base. AttributeBase.__init__(self, values[0].name) def __eq__(self, other): return ConditionBase.__eq__(self, other) and AttributeBase.__eq__( self, other ) def __ne__(self, other): return not self.__eq__(other) class ComparisonCondition(ConditionBase): expression_format = '{0} {operator} {1}' class Equals(ComparisonCondition): expression_operator = '=' class NotEquals(ComparisonCondition): expression_operator = '<>' class LessThan(ComparisonCondition): expression_operator = '<' class LessThanEquals(ComparisonCondition): expression_operator = '<=' class GreaterThan(ComparisonCondition): expression_operator = '>' class GreaterThanEquals(ComparisonCondition): expression_operator = '>=' class In(ComparisonCondition): expression_operator = 'IN' has_grouped_values = True class Between(ConditionBase): expression_operator = 'BETWEEN' expression_format = '{0} {operator} {1} AND {2}' class BeginsWith(ConditionBase): expression_operator = 'begins_with' expression_format = '{operator}({0}, {1})' class Contains(ConditionBase): expression_operator = 'contains' expression_format = '{operator}({0}, {1})' class Size(ConditionAttributeBase): expression_operator = 'size' expression_format = '{operator}({0})' class AttributeType(ConditionBase): expression_operator = 'attribute_type' expression_format = '{operator}({0}, {1})' class AttributeExists(ConditionBase): expression_operator = 'attribute_exists' expression_format = '{operator}({0})' class AttributeNotExists(ConditionBase): expression_operator = 'attribute_not_exists' expression_format = '{operator}({0})' class And(ConditionBase): expression_operator = 'AND' expression_format = '({0} {operator} {1})' class Or(ConditionBase): expression_operator = 'OR' expression_format = '({0} {operator} {1})' class Not(ConditionBase): expression_operator = 'NOT' expression_format = '({operator} {0})' [docs]class Key(AttributeBase): pass [docs]class Attr(AttributeBase):  """Represents an DynamoDB item's attribute.""" [docs] def ne(self, value):  """Creates a condition where the attribute is not equal to the value  :param value: The value that the attribute is not equal to.  """ return NotEquals(self, value) [docs] def is_in(self, value):  """Creates a condition where the attribute is in the value,  :type value: list  :param value: The value that the attribute is in.  """ return In(self, value) [docs] def exists(self):  """Creates a condition where the attribute exists.""" return AttributeExists(self) [docs] def not_exists(self):  """Creates a condition where the attribute does not exist.""" return AttributeNotExists(self) [docs] def contains(self, value):  """Creates a condition where the attribute contains the value.  :param value: The value the attribute contains.  """ return Contains(self, value) [docs] def size(self):  """Creates a condition for the attribute size.  Note another AttributeBase method must be called on the returned  size condition to be a valid DynamoDB condition.  """ return Size(self) [docs] def attribute_type(self, value):  """Creates a condition for the attribute type.  :param value: The type of the attribute.  """ return AttributeType(self, value) BuiltConditionExpression = namedtuple( 'BuiltConditionExpression', [ 'condition_expression', 'attribute_name_placeholders', 'attribute_value_placeholders', ], ) class ConditionExpressionBuilder:  """This class is used to build condition expressions with placeholders""" def __init__(self): self._name_count = 0 self._value_count = 0 self._name_placeholder = 'n' self._value_placeholder = 'v' def _get_name_placeholder(self): return '#' + self._name_placeholder + str(self._name_count) def _get_value_placeholder(self): return ':' + self._value_placeholder + str(self._value_count) def reset(self):  """Resets the placeholder name and values""" self._name_count = 0 self._value_count = 0 def build_expression(self, condition, is_key_condition=False):  """Builds the condition expression and the dictionary of placeholders.  :type condition: ConditionBase  :param condition: A condition to be built into a condition expression  string with any necessary placeholders.  :type is_key_condition: Boolean  :param is_key_condition: True if the expression is for a  KeyConditionExpression. False otherwise.  :rtype: (string, dict, dict)  :returns: Will return a string representing the condition with  placeholders inserted where necessary, a dictionary of  placeholders for attribute names, and a dictionary of  placeholders for attribute values. Here is a sample return value:  ('#n0 = :v0', {'#n0': 'myattribute'}, {':v1': 'myvalue'})  """ if not isinstance(condition, ConditionBase): raise DynamoDBNeedsConditionError(condition) attribute_name_placeholders = {} attribute_value_placeholders = {} condition_expression = self._build_expression( condition, attribute_name_placeholders, attribute_value_placeholders, is_key_condition=is_key_condition, ) return BuiltConditionExpression( condition_expression=condition_expression, attribute_name_placeholders=attribute_name_placeholders, attribute_value_placeholders=attribute_value_placeholders, ) def _build_expression( self, condition, attribute_name_placeholders, attribute_value_placeholders, is_key_condition, ): expression_dict = condition.get_expression() replaced_values = [] for value in expression_dict['values']: # Build the necessary placeholders for that value. # Placeholders are built for both attribute names and values. replaced_value = self._build_expression_component( value, attribute_name_placeholders, attribute_value_placeholders, condition.has_grouped_values, is_key_condition, ) replaced_values.append(replaced_value) # Fill out the expression using the operator and the # values that have been replaced with placeholders. return expression_dict['format'].format( *replaced_values, operator=expression_dict['operator'] ) def _build_expression_component( self, value, attribute_name_placeholders, attribute_value_placeholders, has_grouped_values, is_key_condition, ): # Continue to recurse if the value is a ConditionBase in order # to extract out all parts of the expression. if isinstance(value, ConditionBase): return self._build_expression( value, attribute_name_placeholders, attribute_value_placeholders, is_key_condition, ) # If it is not a ConditionBase, we can recurse no further. # So we check if it is an attribute and add placeholders for # its name elif isinstance(value, AttributeBase): if is_key_condition and not isinstance(value, Key): raise DynamoDBNeedsKeyConditionError( f'Attribute object {value.name} is of type {type(value)}. ' f'KeyConditionExpression only supports Attribute objects ' f'of type Key' ) return self._build_name_placeholder( value, attribute_name_placeholders ) # If it is anything else, we treat it as a value and thus placeholders # are needed for the value. else: return self._build_value_placeholder( value, attribute_value_placeholders, has_grouped_values ) def _build_name_placeholder(self, value, attribute_name_placeholders): attribute_name = value.name # Figure out which parts of the attribute name that needs replacement. attribute_name_parts = ATTR_NAME_REGEX.findall(attribute_name) # Add a temporary placeholder for each of these parts. placeholder_format = ATTR_NAME_REGEX.sub('%s', attribute_name) str_format_args = [] for part in attribute_name_parts: name_placeholder = self._get_name_placeholder() self._name_count += 1 str_format_args.append(name_placeholder) # Add the placeholder and value to dictionary of name placeholders. attribute_name_placeholders[name_placeholder] = part # Replace the temporary placeholders with the designated placeholders. return placeholder_format % tuple(str_format_args) def _build_value_placeholder( self, value, attribute_value_placeholders, has_grouped_values=False ): # If the values are grouped, we need to add a placeholder for # each element inside of the actual value. if has_grouped_values: placeholder_list = [] for v in value: value_placeholder = self._get_value_placeholder() self._value_count += 1 placeholder_list.append(value_placeholder) attribute_value_placeholders[value_placeholder] = v # Assuming the values are grouped by parenthesis. # IN is the currently the only one that uses this so it maybe # needed to be changed in future. return '(' + ', '.join(placeholder_list) + ')' # Otherwise, treat the value as a single value that needs only # one placeholder. else: value_placeholder = self._get_value_placeholder() self._value_count += 1 attribute_value_placeholders[value_placeholder] = value return value_placeholder 

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