class Aws::DynamoDB::Types::UpdateItemInput

Represents the input of an `UpdateItem` operation.

@note When making an API call, you may pass UpdateItemInput

data as a hash:

    {
      table_name: "TableName", # required
      key: { # required
        "AttributeName" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
      },
      attribute_updates: {
        "AttributeName" => {
          value: "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
          action: "ADD", # accepts ADD, PUT, DELETE
        },
      },
      expected: {
        "AttributeName" => {
          value: "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
          exists: false,
          comparison_operator: "EQ", # accepts EQ, NE, IN, LE, LT, GE, GT, BETWEEN, NOT_NULL, NULL, CONTAINS, NOT_CONTAINS, BEGINS_WITH
          attribute_value_list: ["value"], # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
        },
      },
      conditional_operator: "AND", # accepts AND, OR
      return_values: "NONE", # accepts NONE, ALL_OLD, UPDATED_OLD, ALL_NEW, UPDATED_NEW
      return_consumed_capacity: "INDEXES", # accepts INDEXES, TOTAL, NONE
      return_item_collection_metrics: "SIZE", # accepts SIZE, NONE
      update_expression: "UpdateExpression",
      condition_expression: "ConditionExpression",
      expression_attribute_names: {
        "ExpressionAttributeNameVariable" => "AttributeName",
      },
      expression_attribute_values: {
        "ExpressionAttributeValueVariable" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
      },
    }

@!attribute [rw] table_name

The name of the table containing the item to update.
@return [String]

@!attribute [rw] key

The primary key of the item to be updated. Each element consists of
an attribute name and a value for that attribute.

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.
@return [Hash<String,Types::AttributeValue>]

@!attribute [rw] attribute_updates

This is a legacy parameter. Use `UpdateExpression` instead. For more
information, see [AttributeUpdates][1] in the *Amazon DynamoDB
Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.AttributeUpdates.html
@return [Hash<String,Types::AttributeValueUpdate>]

@!attribute [rw] expected

This is a legacy parameter. Use `ConditionExpression` instead. For
more information, see [Expected][1] in the *Amazon DynamoDB
Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.Expected.html
@return [Hash<String,Types::ExpectedAttributeValue>]

@!attribute [rw] conditional_operator

This is a legacy parameter. Use `ConditionExpression` instead. For
more information, see [ConditionalOperator][1] in the *Amazon
DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.ConditionalOperator.html
@return [String]

@!attribute [rw] return_values

Use `ReturnValues` if you want to get the item attributes as they
appear before or after they are updated. For `UpdateItem`, 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` - Returns all of the attributes of the item, as they
  appeared before the UpdateItem operation.

* `UPDATED_OLD` - Returns only the updated attributes, as they
  appeared before the UpdateItem operation.

* `ALL_NEW` - Returns all of the attributes of the item, as they
  appear after the UpdateItem operation.

* `UPDATED_NEW` - Returns only the updated attributes, as they
  appear after the UpdateItem operation.

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 values returned are strongly consistent.
@return [String]

@!attribute [rw] return_consumed_capacity

Determines the level of detail about provisioned throughput
consumption that is returned in the response:

* `INDEXES` - The response includes the aggregate `ConsumedCapacity`
  for the operation, together with `ConsumedCapacity` for each table
  and secondary index that was accessed.

  Note that some operations, such as `GetItem` and `BatchGetItem`,
  do not access any indexes at all. In these cases, specifying
  `INDEXES` will only return `ConsumedCapacity` information for
  table(s).

* `TOTAL` - The response includes only the aggregate
  `ConsumedCapacity` for the operation.

* `NONE` - No `ConsumedCapacity` details are included in the
  response.
@return [String]

@!attribute [rw] return_item_collection_metrics

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.
@return [String]

@!attribute [rw] update_expression

An expression that defines one or more attributes to be updated, the
action to be performed on them, and new values for them.

The following action values are available for `UpdateExpression`.

* `SET` - Adds one or more attributes and values to an item. If any
  of these attributes already exist, they are replaced by the new
  values. You can also use `SET` to add or subtract from an
  attribute that is of type Number. For example: `SET myNum = myNum
  + :val`

  `SET` supports the following functions:

  * `if_not_exists (path, operand)` - if the item does not contain
    an attribute at the specified path, then `if_not_exists`
    evaluates to operand; otherwise, it evaluates to path. You can
    use this function to avoid overwriting an attribute that may
    already be present in the item.

  * `list_append (operand, operand)` - evaluates to a list with a
    new element added to it. You can append the new element to the
    start or the end of the list by reversing the order of the
    operands.

  These function names are case-sensitive.

* `REMOVE` - Removes one or more attributes from an item.

* `ADD` - Adds the specified value to the item, if the attribute
  does not already exist. If the attribute does exist, then the
  behavior of `ADD` depends on the data type of the attribute:

  * If the existing attribute is a number, and if `Value` is also a
    number, then `Value` is mathematically added to the existing
    attribute. If `Value` is a negative number, then it is
    subtracted from the existing attribute.

    <note markdown="1"> If you use `ADD` to increment or decrement a number value for an
    item that doesn't exist before the update, DynamoDB uses `0` as
    the initial value.

     Similarly, if you use `ADD` for an existing item to increment or
    decrement an attribute value that doesn't exist before the
    update, DynamoDB uses `0` as the initial value. For example,
    suppose that the item you want to update doesn't have an
    attribute named `itemcount`, but you decide to `ADD` the number
    `3` to this attribute anyway. DynamoDB will create the
    `itemcount` attribute, set its initial value to `0`, and finally
    add `3` to it. The result will be a new `itemcount` attribute in
    the item, with a value of `3`.

     </note>

  * If the existing data type is a set and if `Value` is also a set,
    then `Value` is added to the existing set. For example, if the
    attribute value is the set `[1,2]`, and the `ADD` action
    specified `[3]`, then the final attribute value is `[1,2,3]`. An
    error occurs if an `ADD` action is specified for a set attribute
    and the attribute type specified does not match the existing set
    type.

    Both sets must have the same primitive data type. For example,
    if the existing data type is a set of strings, the `Value` must
    also be a set of strings.

  The `ADD` action only supports Number and set data types. In
  addition, `ADD` can only be used on top-level attributes, not
  nested attributes.

* `DELETE` - Deletes an element from a set.

  If a set of values is specified, then those values are subtracted
  from the old set. For example, if the attribute value was the set
  `[a,b,c]` and the `DELETE` action specifies `[a,c]`, then the
  final attribute value is `[b]`. Specifying an empty set is an
  error.

  The `DELETE` action only supports set data types. In addition,
  `DELETE` can only be used on top-level attributes, not nested
  attributes.

You can have many actions in a single expression, such as the
following: `SET a=:value1, b=:value2 DELETE :value3, :value4,
:value5`

For more information on update expressions, see [Modifying Items and
Attributes][1] in the *Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.Modifying.html
@return [String]

@!attribute [rw] condition_expression

A condition that must be satisfied in order for a conditional update
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 [Specifying
Conditions][1] in the *Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.SpecifyingConditions.html
@return [String]

@!attribute [rw] expression_attribute_names

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][1] 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`

^

<note markdown="1"> Tokens that begin with the **\:** character are *expression
attribute values*, which are placeholders for the actual value at
runtime.

 </note>

For more information about expression attribute names, see
[Specifying Item Attributes][2] in the *Amazon DynamoDB Developer
Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ReservedWords.html
[2]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.AccessingItemAttributes.html
@return [Hash<String,String>]

@!attribute [rw] expression_attribute_values

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][1] in the *Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.SpecifyingConditions.html
@return [Hash<String,Types::AttributeValue>]

@see docs.aws.amazon.com/goto/WebAPI/dynamodb-2012-08-10/UpdateItemInput AWS API Documentation

Constants

SENSITIVE