Delete Item
dynamodb_delete_item | R Documentation |
Deletes a single item in a table by primary key¶
Description¶
Deletes a single item in a table by primary key. You can perform a conditional delete operation that deletes the item if it exists, or if it has an expected attribute value.
In addition to deleting an item, you can also return the item's
attribute values in the same operation, using the ReturnValues
parameter.
Unless you specify conditions, the delete_item
is an idempotent
operation; running it multiple times on the same item or attribute does
not result in an error response.
Conditional deletes are useful for deleting items only if specific conditions are met. If those conditions are met, DynamoDB performs the delete. Otherwise, the item is not deleted.
Usage¶
dynamodb_delete_item(TableName, Key, Expected, ConditionalOperator,
ReturnValues, ReturnConsumedCapacity, ReturnItemCollectionMetrics,
ConditionExpression, ExpressionAttributeNames,
ExpressionAttributeValues, ReturnValuesOnConditionCheckFailure)
Arguments¶
TableName
[required] The name of the table from which to delete the item. You can also provide the Amazon Resource Name (ARN) of the table in this parameter.
Key
[required] A map of attribute names to
AttributeValue
objects, representing the primary key of the item to delete.For the primary key, you must provide all of the key attributes. For example, with a simple primary key, you only need to provide a value for the partition key. For a composite primary key, you must provide values for both the partition key and the sort key.
Expected
This is a legacy parameter. Use
ConditionExpression
instead. For more information, see Expected in the Amazon DynamoDB Developer Guide.ConditionalOperator
This is a legacy parameter. Use
ConditionExpression
instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.ReturnValues
Use
ReturnValues
if you want to get the item attributes as they appeared before they were deleted. Fordelete_item
, the valid values are:NONE
- IfReturnValues
is not specified, or if its value isNONE
, then nothing is returned. (This setting is the default forReturnValues
.)ALL_OLD
- The content of the old item is returned.
There is no additional cost associated with requesting a return value aside from the small network and processing overhead of receiving a larger response. No read capacity units are consumed.
The
ReturnValues
parameter is used by several DynamoDB operations; however,delete_item
does not recognize any values other thanNONE
orALL_OLD
.ReturnConsumedCapacity
ReturnItemCollectionMetrics
Determines whether item collection metrics are returned. If set to
SIZE
, the response includes statistics about item collections, if any, that were modified during the operation are returned in the response. If set toNONE
(the default), no statistics are returned.ConditionExpression
A condition that must be satisfied in order for a conditional
delete_item
to succeed.An expression can contain any of the following:
Functions:
attribute_exists | attribute_not_exists | attribute_type | contains | begins_with | size
These function names are case-sensitive.
Comparison operators:
= | <> | < | > | <= | >= | BETWEEN | IN
Logical operators:
AND | OR | NOT
For more information about condition expressions, see Condition Expressions in the Amazon DynamoDB Developer Guide.
ExpressionAttributeNames
One or more substitution tokens for attribute names in an expression. The following are some use cases for using
ExpressionAttributeNames
:To access an attribute whose name conflicts with a DynamoDB reserved word.
To create a placeholder for repeating occurrences of an attribute name in an expression.
To prevent special characters in an attribute name from being misinterpreted in an expression.
Use the # character in an expression to dereference an attribute name. For example, consider the following attribute name:
Percentile
The name of this attribute conflicts with a reserved word, so it cannot be used directly in an expression. (For the complete list of reserved words, see Reserved Words in the Amazon DynamoDB Developer Guide). To work around this, you could specify the following for
ExpressionAttributeNames
:{"#P":"Percentile"}
You could then use this substitution in an expression, as in this example:
#P = :val
Tokens that begin with the : character are expression attribute values, which are placeholders for the actual value at runtime.
For more information on expression attribute names, see Specifying Item Attributes in the Amazon DynamoDB Developer Guide.
ExpressionAttributeValues
One or more values that can be substituted in an expression.
Use the : (colon) character in an expression to dereference an attribute value. For example, suppose that you wanted to check whether the value of the ProductStatus attribute was one of the following:
Available | Backordered | Discontinued
You would first need to specify
ExpressionAttributeValues
as follows:{ ":avail":{"S":"Available"}, ":back":{"S":"Backordered"}, ":disc":{"S":"Discontinued"} }
You could then use these values in an expression, such as this:
ProductStatus IN (:avail, :back, :disc)
For more information on expression attribute values, see Condition Expressions in the Amazon DynamoDB Developer Guide.
ReturnValuesOnConditionCheckFailure
An optional parameter that returns the item attributes for a
delete_item
operation that failed a condition check.There is no additional cost associated with requesting a return value aside from the small network and processing overhead of receiving a larger response. No read capacity units are consumed.
Value¶
A list with the following syntax:
list(
Attributes = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
),
ConsumedCapacity = list(
TableName = "string",
CapacityUnits = 123.0,
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
Table = list(
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
CapacityUnits = 123.0
),
LocalSecondaryIndexes = list(
list(
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
CapacityUnits = 123.0
)
),
GlobalSecondaryIndexes = list(
list(
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
CapacityUnits = 123.0
)
)
),
ItemCollectionMetrics = list(
ItemCollectionKey = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
),
SizeEstimateRangeGB = list(
123.0
)
)
)
Request syntax¶
svc$delete_item(
TableName = "string",
Key = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
),
Expected = list(
list(
Value = list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
),
Exists = TRUE|FALSE,
ComparisonOperator = "EQ"|"NE"|"IN"|"LE"|"LT"|"GE"|"GT"|"BETWEEN"|"NOT_NULL"|"NULL"|"CONTAINS"|"NOT_CONTAINS"|"BEGINS_WITH",
AttributeValueList = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
)
)
),
ConditionalOperator = "AND"|"OR",
ReturnValues = "NONE"|"ALL_OLD"|"UPDATED_OLD"|"ALL_NEW"|"UPDATED_NEW",
ReturnConsumedCapacity = "INDEXES"|"TOTAL"|"NONE",
ReturnItemCollectionMetrics = "SIZE"|"NONE",
ConditionExpression = "string",
ExpressionAttributeNames = list(
"string"
),
ExpressionAttributeValues = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
),
ReturnValuesOnConditionCheckFailure = "ALL_OLD"|"NONE"
)
Examples¶
## Not run:
# This example deletes an item from the Music table.
svc$delete_item(
Key = list(
Artist = list(
S = "No One You Know"
),
SongTitle = list(
S = "Scared of My Shadow"
)
),
TableName = "Music"
)
## End(Not run)