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Tweak comparison to treat NULL/NOT_NULL correctly. (#1709)

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The AWS documentation says that a ComparisonOperator of NULL means
the attribute should not exist, whereas NOT_NULL means that the
attribute should exist. It explicitly says that an attribute with a
value of NULL is considered to exist, which contradicts our previous
implementation. This affects both put_item and get_item in dynamodb2.

https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Condition.html
This commit is contained in:
Gary Donovan 2018-07-13 19:11:10 +10:00 • committed by Terry Cain
commit 802402bdba
4 changed files with 107 additions and 12 deletions
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6
moto/dynamodb2/comparisons.py
View file

@ -29,8 +29,10 @@ COMPARISON_FUNCS = {
'GT': GT_FUNCTION,
'>': GT_FUNCTION,
'NULL': lambda item_value: item_value is None,
'NOT_NULL': lambda item_value: item_value is not None,
# NULL means the value should not exist at all
'NULL': lambda item_value: False,
# NOT_NULL means the value merely has to exist, and values of None are valid
'NOT_NULL': lambda item_value: True,
'CONTAINS': lambda item_value, test_value: test_value in item_value,
'NOT_CONTAINS': lambda item_value, test_value: test_value not in item_value,
'BEGINS_WITH': lambda item_value, test_value: item_value.startswith(test_value),

18
moto/dynamodb2/models.py
View file

@ -409,7 +409,8 @@ class Table(BaseModel):
current_attr = current
for key, val in expected.items():
if 'Exists' in val and val['Exists'] is False:
if 'Exists' in val and val['Exists'] is False \
or 'ComparisonOperator' in val and val['ComparisonOperator'] == 'NULL':
if key in current_attr:
raise ValueError("The conditional request failed")
elif key not in current_attr:
@ -419,8 +420,10 @@ class Table(BaseModel):
elif 'ComparisonOperator' in val:
comparison_func = get_comparison_func(
val['ComparisonOperator'])
dynamo_types = [DynamoType(ele) for ele in val[
"AttributeValueList"]]
dynamo_types = [
DynamoType(ele) for ele in
val.get("AttributeValueList", [])
]
for t in dynamo_types:
if not comparison_func(current_attr[key].value, t.value):
raise ValueError('The conditional request failed')
@ -827,7 +830,8 @@ class DynamoDBBackend(BaseBackend):
expected = {}
for key, val in expected.items():
if 'Exists' in val and val['Exists'] is False:
if 'Exists' in val and val['Exists'] is False \
or 'ComparisonOperator' in val and val['ComparisonOperator'] == 'NULL':
if key in item_attr:
raise ValueError("The conditional request failed")
elif key not in item_attr:
@ -837,8 +841,10 @@ class DynamoDBBackend(BaseBackend):
elif 'ComparisonOperator' in val:
comparison_func = get_comparison_func(
val['ComparisonOperator'])
dynamo_types = [DynamoType(ele) for ele in val[
"AttributeValueList"]]
dynamo_types = [
DynamoType(ele) for ele in
val.get("AttributeValueList", [])
]
for t in dynamo_types:
if not comparison_func(item_attr[key].value, t.value):
raise ValueError('The conditional request failed')