Class UpdateItemRequest

Namespace: Amazon.DynamoDBv2.Model

Assembly: AWSSDK.DynamoDBv2.dll

Container for the parameters to the UpdateItem operation. Edits an existing item's attributes, or adds a new item to the table if it does not already exist. You can put, delete, or add attribute values. You can also perform a conditional update on an existing item (insert a new attribute name-value pair if it doesn't exist, or replace an existing name-value pair if it has certain expected attribute values).

You can also return the item's attribute values in the same

UpdateItem

operation using the

ReturnValues

parameter.

public class UpdateItemRequest : AmazonDynamoDBRequest

Inheritance: object

AmazonDynamoDBRequest

UpdateItemRequest

Constructors

UpdateItemRequest()

Empty constructor used to set properties independently even when a simple constructor is available

public UpdateItemRequest()

UpdateItemRequest(string, Dictionary<string, AttributeValue>, Dictionary<string, AttributeValueUpdate>)

Instantiates UpdateItemRequest with the parameterized properties

public UpdateItemRequest(string tableName, Dictionary<string, AttributeValue> key, Dictionary<string, AttributeValueUpdate> attributeUpdates)

Parameters

tableName string

The name of the table containing the item to update.

key Dictionary<string, AttributeValue>

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.

attributeUpdates Dictionary<string, AttributeValueUpdate>

This is a legacy parameter. Use

UpdateExpression

instead. For more information, see AttributeUpdates in the Amazon DynamoDB Developer Guide.

UpdateItemRequest(string, Dictionary<string, AttributeValue>, Dictionary<string, AttributeValueUpdate>, ReturnValue)

Instantiates UpdateItemRequest with the parameterized properties

public UpdateItemRequest(string tableName, Dictionary<string, AttributeValue> key, Dictionary<string, AttributeValueUpdate> attributeUpdates, ReturnValue returnValues)

Parameters

tableName string

The name of the table containing the item to update.

key Dictionary<string, AttributeValue>

attributeUpdates Dictionary<string, AttributeValueUpdate>

This is a legacy parameter. Use

UpdateExpression

instead. For more information, see AttributeUpdates in the Amazon DynamoDB Developer Guide.

returnValues ReturnValue

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.

Properties

AttributeUpdates

Gets and sets the property AttributeUpdates.

This is a legacy parameter. Use

UpdateExpression

instead. For more information, see AttributeUpdates in the Amazon DynamoDB Developer Guide.

public Dictionary<string, AttributeValueUpdate> AttributeUpdates { get; set; }

Property Value

Dictionary<string, AttributeValueUpdate>

ConditionExpression

Gets and sets the property ConditionExpression.

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 in the Amazon DynamoDB Developer Guide.

public string ConditionExpression { get; set; }

Property Value

string

ConditionalOperator

Gets and sets the property ConditionalOperator.

This is a legacy parameter. Use

ConditionExpression

instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.

public ConditionalOperator ConditionalOperator { get; set; }

Property Value

ConditionalOperator

Expected

Gets and sets the property Expected.

This is a legacy parameter. Use

ConditionExpression

instead. For more information, see Expected in the Amazon DynamoDB Developer Guide.

public Dictionary<string, ExpectedAttributeValue> Expected { get; set; }

Property Value

Dictionary<string, ExpectedAttributeValue>

ExpressionAttributeNames

Gets and sets the property 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
```

note

Tokens that begin with the : character are expression attribute values, which are placeholders for the actual value at runtime.

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

public Dictionary<string, string> ExpressionAttributeNames { get; set; }

Property Value

Dictionary<string, string>

ExpressionAttributeValues

Gets and sets the property 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.

public Dictionary<string, AttributeValue> ExpressionAttributeValues { get; set; }

Property Value

Dictionary<string, AttributeValue>

Key

Gets and sets the property 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.

public Dictionary<string, AttributeValue> Key { get; set; }

Property Value

Dictionary<string, AttributeValue>

ReturnConsumedCapacity

Gets and sets the property ReturnConsumedCapacity.

public ReturnConsumedCapacity ReturnConsumedCapacity { get; set; }

Property Value

ReturnConsumedCapacity

ReturnItemCollectionMetrics

Gets and sets the property 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.

public ReturnItemCollectionMetrics ReturnItemCollectionMetrics { get; set; }

Property Value

ReturnItemCollectionMetrics

ReturnValues

Gets and sets the property ReturnValues.

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.

public ReturnValue ReturnValues { get; set; }

Property Value

ReturnValue

TableName

Gets and sets the property TableName.

The name of the table containing the item to update.

public string TableName { get; set; }

Property Value

string

UpdateExpression

Gets and sets the property UpdateExpression.

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
  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
```
  .
- 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 in the Amazon DynamoDB Developer Guide.

public string UpdateExpression { get; set; }

Property Value

string

Table of Contents

Class UpdateItemRequest

Constructors

UpdateItemRequest()

UpdateItemRequest(string, Dictionary<string, AttributeValue>, Dictionary<string, AttributeValueUpdate>)

Parameters

UpdateItemRequest(string, Dictionary<string, AttributeValue>, Dictionary<string, AttributeValueUpdate>, ReturnValue)

Parameters

Properties

AttributeUpdates

Property Value

ConditionExpression

Property Value

ConditionalOperator

Property Value

Expected

Property Value

ExpressionAttributeNames

note

Property Value

ExpressionAttributeValues

Property Value

Key

Property Value

ReturnConsumedCapacity

Property Value

ReturnItemCollectionMetrics

Property Value

ReturnValues

Property Value

TableName

Property Value

UpdateExpression

note

Property Value