dynamodb_put_item: Creates a new item, or replaces an old item with a new item

Description

Creates a new item, or replaces an old item with a new item. If an item that has the same primary key as the new item already exists in the specified table, the new item completely replaces the existing item. You can perform a conditional put operation (add a new item if one with the specified primary key doesn't exist), or replace an existing item if it has certain attribute values. You can return the item's attribute values in the same operation, using the ReturnValues parameter.

Usage

dynamodb_put_item(TableName, Item, Expected, ReturnValues,
  ReturnConsumedCapacity, ReturnItemCollectionMetrics,
  ConditionalOperator, ConditionExpression, ExpressionAttributeNames,
  ExpressionAttributeValues)

Arguments

TableName

[required] The name of the table to contain the item.

Item

[required] A map of attribute name/value pairs, one for each attribute. Only the primary key attributes are required; you can optionally provide other attribute name-value pairs for the item.

You must provide all of the attributes for the primary key. 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 both values for both the partition key and the sort key.

If you specify any attributes that are part of an index key, then the data types for those attributes must match those of the schema in the table's attribute definition.

For more information about primary keys, see Primary Key in the Amazon DynamoDB Developer Guide.

Each element in the Item map is an AttributeValue object.

Expected

This is a legacy parameter. Use ConditionExpression instead. For more information, see Expected in the Amazon DynamoDB Developer Guide.

ReturnValues

Use ReturnValues if you want to get the item attributes as they appeared before they were updated with the PutItem request. For PutItem, 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 - If PutItem overwrote an attribute name-value pair, then the content of the old item is returned.

The ReturnValues parameter is used by several DynamoDB operations; however, PutItem 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.

ConditionalOperator

This is a legacy parameter. Use ConditionExpression instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.

ConditionExpression

A condition that must be satisfied in order for a conditional PutItem operation 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 on 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.

Request syntax

svc$put_item(
  TableName = "string",
  Item = 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
        )
      )
    )
  ),
  ReturnValues = "NONE"|"ALL_OLD"|"UPDATED_OLD"|"ALL_NEW"|"UPDATED_NEW",
  ReturnConsumedCapacity = "INDEXES"|"TOTAL"|"NONE",
  ReturnItemCollectionMetrics = "SIZE"|"NONE",
  ConditionalOperator = "AND"|"OR",
  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
    )
  )
)

Details

This topic provides general information about the PutItem API.

For information on how to call the PutItem API using the AWS SDK in specific languages, see the following:

When you add an item, the primary key attributes are the only required attributes. Attribute values cannot be null. String and Binary type attributes must have lengths greater than zero. Set type attributes cannot be empty. Requests with empty values will be rejected with a ValidationException exception.

To prevent a new item from replacing an existing item, use a conditional expression that contains the attribute_not_exists function with the name of the attribute being used as the partition key for the table. Since every record must contain that attribute, the attribute_not_exists function will only succeed if no matching item exists.

For more information about PutItem, see Working with Items in the Amazon DynamoDB Developer Guide.

Examples

Run this code

# NOT RUN {
# This example adds a new item to the Music table.
# }
# NOT RUN {
svc$put_item(
  Item = list(
    AlbumTitle = list(
      S = "Somewhat Famous"
    ),
    Artist = list(
      S = "No One You Know"
    ),
    SongTitle = list(
      S = "Call Me Today"
    )
  ),
  ReturnConsumedCapacity = "TOTAL",
  TableName = "Music"
)
# }
# NOT RUN {
# }

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