def update_item(options = {})
      options = options.merge(table_name: @name)
      resp = @client.update_item(options)
      resp.data
    end
def update_item(options = {})
      options = options.merge(table_name: @name)
      resp = @client.update_item(options)
      resp.data
    end
@example Request syntax with placeholder values

   table.update_item({
     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>
     },
   })
 @param [Hash] options ({})
 @option options [required, Hash<String,Types::AttributeValue>] :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.
 @option options [Hash<String,Types::AttributeValueUpdate>] :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
 @option options [Hash<String,Types::ExpectedAttributeValue>] :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
 @option options [String] :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
 @option options [String] :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.
 @option options [String] :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.
 @option options [String] :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.
 @option options [String] :update_expression
   An expression that defines one or more attributes to be updated, the
   action to be performed on them, and new value(s) 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 attribute 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
 @option options [String] :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 on condition expressions, see [Specifying
   Conditions][1] in the *Amazon DynamoDB Developer Guide*.



   [1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.SpecifyingConditions.html
 @option options [Hash<String,String>] :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 on expression attribute names, see [Accessing
   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
 @option options [Hash<String,Types::AttributeValue>] :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 [Specifying
   Conditions][1] in the *Amazon DynamoDB Developer Guide*.



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