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ProjectionExpression works with table.scan()

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This commit is contained in:
IVIURRAY 2019-06-26 21:54:48 +01:00
parent 2275c53b3e
commit e50ce7287d
3 changed files with 98 additions and 5 deletions
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14
moto/dynamodb2/models.py
View File

@ -724,7 +724,7 @@ class Table(BaseModel):
if idx_col_set.issubset(set(hash_set.attrs)):
yield hash_set
def scan(self, filters, limit, exclusive_start_key, filter_expression=None, index_name=None):
def scan(self, filters, limit, exclusive_start_key, filter_expression=None, index_name=None, projection_expression=None):
results = []
scanned_count = 0
all_indexes = self.all_indexes()
@ -763,6 +763,14 @@ class Table(BaseModel):
if passes_all_conditions:
results.append(item)
if projection_expression:
expressions = [x.strip() for x in projection_expression.split(',')]
results = copy.deepcopy(results)
for result in results:
for attr in list(result.attrs):
if attr not in expressions:
result.attrs.pop(attr)
results, last_evaluated_key = self._trim_results(results, limit,
exclusive_start_key, index_name)
return results, scanned_count, last_evaluated_key
@ -962,7 +970,7 @@ class DynamoDBBackend(BaseBackend):
return table.query(hash_key, range_comparison, range_values, limit,
exclusive_start_key, scan_index_forward, projection_expression, index_name, filter_expression, **filter_kwargs)
def scan(self, table_name, filters, limit, exclusive_start_key, filter_expression, expr_names, expr_values, index_name):
def scan(self, table_name, filters, limit, exclusive_start_key, filter_expression, expr_names, expr_values, index_name, projection_expression):
table = self.tables.get(table_name)
if not table:
return None, None, None
@ -977,7 +985,7 @@ class DynamoDBBackend(BaseBackend):
else:
filter_expression = Op(None, None) # Will always eval to true
return table.scan(scan_filters, limit, exclusive_start_key, filter_expression, index_name)
return table.scan(scan_filters, limit, exclusive_start_key, filter_expression, index_name, projection_expression)
def update_item(self, table_name, key, update_expression, attribute_updates, expression_attribute_names,
expression_attribute_values, expected=None):

5
moto/dynamodb2/responses.py
View File

@ -558,7 +558,7 @@ class DynamoHandler(BaseResponse):
filter_expression = self.body.get('FilterExpression')
expression_attribute_values = self.body.get('ExpressionAttributeValues', {})
expression_attribute_names = self.body.get('ExpressionAttributeNames', {})
projection_expression = self.body.get('ProjectionExpression')
exclusive_start_key = self.body.get('ExclusiveStartKey')
limit = self.body.get("Limit")
index_name = self.body.get('IndexName')
@ -570,7 +570,8 @@ class DynamoHandler(BaseResponse):
filter_expression,
expression_attribute_names,
expression_attribute_values,
index_name)
index_name,
projection_expression)
except InvalidIndexNameError as err:
er = 'com.amazonaws.dynamodb.v20111205#ValidationException'
return self.error(er, str(err))

84
tests/test_dynamodb2/test_dynamodb.py
View File

@ -452,6 +452,90 @@ def test_basic_projection_expressions():
assert 'body' in results['Items'][1]
assert 'forum_name' in results['Items'][1]
@mock_dynamodb2
def test_basic_projection_expressions_using_scan():
dynamodb = boto3.resource('dynamodb', region_name='us-east-1')
# Create the DynamoDB table.
table = dynamodb.create_table(
TableName='users',
KeySchema=[
{
'AttributeName': 'forum_name',
'KeyType': 'HASH'
},
{
'AttributeName': 'subject',
'KeyType': 'RANGE'
},
],
AttributeDefinitions=[
{
'AttributeName': 'forum_name',
'AttributeType': 'S'
},
{
'AttributeName': 'subject',
'AttributeType': 'S'
},
],
ProvisionedThroughput={
'ReadCapacityUnits': 5,
'WriteCapacityUnits': 5
}
)
table = dynamodb.Table('users')
table.put_item(Item={
'forum_name': 'the-key',
'subject': '123',
'body': 'some test message'
})
table.put_item(Item={
'forum_name': 'not-the-key',
'subject': '123',
'body': 'some other test message'
})
# Test a query returning all items
results = table.scan(
FilterExpression=Key('forum_name').eq(
'the-key'),
ProjectionExpression='body, subject'
)
assert 'body' in results['Items'][0]
assert results['Items'][0]['body'] == 'some test message'
assert 'subject' in results['Items'][0]
table.put_item(Item={
'forum_name': 'the-key',
'subject': '1234',
'body': 'yet another test message'
})
results = table.scan(
FilterExpression=Key('forum_name').eq(
'the-key'),
ProjectionExpression='body'
)
assert 'body' in results['Items'][0]
assert 'subject' not in results['Items'][0]
assert results['Items'][0]['body'] == 'some test message'
assert 'body' in results['Items'][1]
assert 'subject' not in results['Items'][1]
assert results['Items'][1]['body'] == 'yet another test message'
# The projection expression should not remove data from storage
results = table.query(
KeyConditionExpression=Key('forum_name').eq(
'the-key'),
)
assert 'subject' in results['Items'][0]
assert 'body' in results['Items'][1]
assert 'forum_name' in results['Items'][1]
@mock_dynamodb2
def test_basic_projection_expressions_with_attr_expression_names():