dynamodb_delete_item: Deletes a single item in a table by primary key

Description Usage Arguments Value Request syntax Examples

View source: R/dynamodb_operations.R

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

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dynamodb_delete_item(TableName, Key, Expected, ConditionalOperator,
  ReturnValues, ReturnConsumedCapacity, ReturnItemCollectionMetrics,
  ConditionExpression, ExpressionAttributeNames,
  ExpressionAttributeValues)

Arguments

TableName

[required] The name of the table from which to delete the item.

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 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. For delete_item, the valid values are:

  • NONE - If ReturnValues is not specified, or if its value is NONE, then nothing is returned. (This setting is the default for ReturnValues.)

  • ALL_OLD - The content of the old item is returned.

The ReturnValues parameter is used by several DynamoDB operations; however, delete_item does not recognize any values other than NONE or ALL_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 to NONE (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.

Value

A list with the following syntax:

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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

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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
    )
  )
)

Examples

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## 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)

paws.database documentation built on Aug. 23, 2021, 9:18 a.m.