Merge pull request #2060 from gregsterin/better-support-for-ddb-expressions
support a bit more of the dynamoDB ConditionExpression syntax
This commit is contained in:
Mike Grima
GitHub
commit
3920f0e16b
@ -31,6 +31,67 @@ def get_empty_str_error():
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))
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def condition_expression_to_expected(condition_expression, expression_attribute_names, expression_attribute_values):
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"""
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Limited condition expression syntax parsing.
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Supports Global Negation ex: NOT(inner expressions).
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Supports simple AND conditions ex: cond_a AND cond_b and cond_c.
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Atomic expressions supported are attribute_exists(key), attribute_not_exists(key) and #key = :value.
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"""
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expected = {}
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if condition_expression and 'OR' not in condition_expression:
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reverse_re = re.compile('^NOT\s*\((.*)\)$')
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reverse_m = reverse_re.match(condition_expression.strip())
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reverse = False
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if reverse_m:
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reverse = True
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condition_expression = reverse_m.group(1)
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cond_items = [c.strip() for c in condition_expression.split('AND')]
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if cond_items:
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exists_re = re.compile('^attribute_exists\s*\((.*)\)$')
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not_exists_re = re.compile(
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'^attribute_not_exists\s*\((.*)\)$')
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equals_re = re.compile('^(#?\w+)\s*=\s*(\:?\w+)')
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for cond in cond_items:
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exists_m = exists_re.match(cond)
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not_exists_m = not_exists_re.match(cond)
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equals_m = equals_re.match(cond)
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if exists_m:
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attribute_name = expression_attribute_names_lookup(exists_m.group(1), expression_attribute_names)
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expected[attribute_name] = {'Exists': True if not reverse else False}
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elif not_exists_m:
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attribute_name = expression_attribute_names_lookup(not_exists_m.group(1), expression_attribute_names)
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expected[attribute_name] = {'Exists': False if not reverse else True}
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elif equals_m:
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attribute_name = expression_attribute_names_lookup(equals_m.group(1), expression_attribute_names)
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attribute_value = expression_attribute_values_lookup(equals_m.group(2), expression_attribute_values)
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expected[attribute_name] = {
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'AttributeValueList': [attribute_value],
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'ComparisonOperator': 'EQ' if not reverse else 'NEQ'}
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return expected
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def expression_attribute_names_lookup(attribute_name, expression_attribute_names):
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if attribute_name.startswith('#') and attribute_name in expression_attribute_names:
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return expression_attribute_names[attribute_name]
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else:
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return attribute_name
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def expression_attribute_values_lookup(attribute_value, expression_attribute_values):
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if isinstance(attribute_value, six.string_types) and \
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attribute_value.startswith(':') and\
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attribute_value in expression_attribute_values:
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return expression_attribute_values[attribute_value]
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else:
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return attribute_value
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class DynamoHandler(BaseResponse):
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def get_endpoint_name(self, headers):
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@ -220,24 +281,13 @@ class DynamoHandler(BaseResponse):
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# expression
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if not expected:
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condition_expression = self.body.get('ConditionExpression')
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if condition_expression and 'OR' not in condition_expression:
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cond_items = [c.strip()
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for c in condition_expression.split('AND')]
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if cond_items:
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expected = {}
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overwrite = False
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exists_re = re.compile('^attribute_exists\s*\((.*)\)$')
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not_exists_re = re.compile(
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'^attribute_not_exists\s*\((.*)\)$')
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for cond in cond_items:
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exists_m = exists_re.match(cond)
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not_exists_m = not_exists_re.match(cond)
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if exists_m:
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expected[exists_m.group(1)] = {'Exists': True}
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elif not_exists_m:
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expected[not_exists_m.group(1)] = {'Exists': False}
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expression_attribute_names = self.body.get('ExpressionAttributeNames', {})
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expression_attribute_values = self.body.get('ExpressionAttributeValues', {})
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expected = condition_expression_to_expected(condition_expression,
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expression_attribute_names,
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expression_attribute_values)
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if expected:
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overwrite = False
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try:
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result = self.dynamodb_backend.put_item(name, item, expected, overwrite)
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@ -590,23 +640,11 @@ class DynamoHandler(BaseResponse):
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# expression
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if not expected:
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condition_expression = self.body.get('ConditionExpression')
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if condition_expression and 'OR' not in condition_expression:
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cond_items = [c.strip()
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for c in condition_expression.split('AND')]
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if cond_items:
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expected = {}
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exists_re = re.compile('^attribute_exists\s*\((.*)\)$')
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not_exists_re = re.compile(
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'^attribute_not_exists\s*\((.*)\)$')
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for cond in cond_items:
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exists_m = exists_re.match(cond)
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not_exists_m = not_exists_re.match(cond)
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if exists_m:
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expected[exists_m.group(1)] = {'Exists': True}
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elif not_exists_m:
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expected[not_exists_m.group(1)] = {'Exists': False}
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expression_attribute_names = self.body.get('ExpressionAttributeNames', {})
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expression_attribute_values = self.body.get('ExpressionAttributeValues', {})
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expected = condition_expression_to_expected(condition_expression,
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expression_attribute_names,
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expression_attribute_values)
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# Support spaces between operators in an update expression
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# E.g. `a = b + c` -> `a=b+c`
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@ -1505,3 +1505,110 @@ def test_dynamodb_streams_2():
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assert 'LatestStreamLabel' in resp['TableDescription']
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assert 'LatestStreamArn' in resp['TableDescription']
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@mock_dynamodb2
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def test_condition_expressions():
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client = boto3.client('dynamodb', region_name='us-east-1')
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dynamodb = boto3.resource('dynamodb', region_name='us-east-1')
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# Create the DynamoDB table.
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client.create_table(
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TableName='test1',
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AttributeDefinitions=[{'AttributeName': 'client', 'AttributeType': 'S'}, {'AttributeName': 'app', 'AttributeType': 'S'}],
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KeySchema=[{'AttributeName': 'client', 'KeyType': 'HASH'}, {'AttributeName': 'app', 'KeyType': 'RANGE'}],
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ProvisionedThroughput={'ReadCapacityUnits': 123, 'WriteCapacityUnits': 123}
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)
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client.put_item(
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TableName='test1',
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Item={
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'client': {'S': 'client1'},
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'app': {'S': 'app1'},
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'match': {'S': 'match'},
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'existing': {'S': 'existing'},
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}
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)
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client.put_item(
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TableName='test1',
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Item={
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'client': {'S': 'client1'},
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'app': {'S': 'app1'},
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'match': {'S': 'match'},
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'existing': {'S': 'existing'},
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},
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ConditionExpression='attribute_exists(#existing) AND attribute_not_exists(#nonexistent) AND #match = :match',
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ExpressionAttributeNames={
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'#existing': 'existing',
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'#nonexistent': 'nope',
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'#match': 'match',
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},
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ExpressionAttributeValues={
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':match': {'S': 'match'}
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}
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)
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client.put_item(
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TableName='test1',
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Item={
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'client': {'S': 'client1'},
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'app': {'S': 'app1'},
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'match': {'S': 'match'},
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'existing': {'S': 'existing'},
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},
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ConditionExpression='NOT(attribute_exists(#nonexistent1) AND attribute_exists(#nonexistent2))',
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ExpressionAttributeNames={
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'#nonexistent1': 'nope',
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'#nonexistent2': 'nope2'
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}
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)
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with assert_raises(client.exceptions.ConditionalCheckFailedException):
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client.put_item(
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TableName='test1',
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Item={
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'client': {'S': 'client1'},
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'app': {'S': 'app1'},
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'match': {'S': 'match'},
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'existing': {'S': 'existing'},
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},
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ConditionExpression='attribute_exists(#nonexistent1) AND attribute_exists(#nonexistent2)',
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ExpressionAttributeNames={
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'#nonexistent1': 'nope',
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'#nonexistent2': 'nope2'
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}
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)
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with assert_raises(client.exceptions.ConditionalCheckFailedException):
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client.put_item(
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TableName='test1',
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Item={
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'client': {'S': 'client1'},
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'app': {'S': 'app1'},
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'match': {'S': 'match'},
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'existing': {'S': 'existing'},
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},
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ConditionExpression='NOT(attribute_not_exists(#nonexistent1) AND attribute_not_exists(#nonexistent2))',
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ExpressionAttributeNames={
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'#nonexistent1': 'nope',
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'#nonexistent2': 'nope2'
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}
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)
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with assert_raises(client.exceptions.ConditionalCheckFailedException):
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client.put_item(
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TableName='test1',
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Item={
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'client': {'S': 'client1'},
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'app': {'S': 'app1'},
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'match': {'S': 'match'},
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'existing': {'S': 'existing'},
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},
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ConditionExpression='attribute_exists(#existing) AND attribute_not_exists(#nonexistent) AND #match = :match',
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ExpressionAttributeNames={
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'#existing': 'existing',
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'#nonexistent': 'nope',
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'#match': 'match',
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},
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ExpressionAttributeValues={
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':match': {'S': 'match2'}
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}
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)
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