AWSDynamoDBUpdateItemInput Class Reference

Inherits from AWSRequest : AWSModel : AWSMTLModel
Declared in AWSDynamoDBModel.h
AWSDynamoDBModel.m

Overview

Represents the input of an UpdateItem operation.

Required parameters: [TableName, Key]

  attributeUpdates

This is a legacy parameter, for backward compatibility. New applications should use UpdateExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception.

This parameter can be used for modifying top-level attributes; however, it does not support individual list or map elements.

The names of attributes to be modified, the action to perform on each, and the new value for each. If you are updating an attribute that is an index key attribute for any indexes on that table, the attribute type must match the index key type defined in the AttributesDefinition of the table description. You can use UpdateItem to update any non-key attributes.

Attribute values cannot be null. String and Binary type attributes must have lengths greater than zero. Set type attributes must not be empty. Requests with empty values will be rejected with a ValidationException exception.

Each AttributeUpdates element consists of an attribute name to modify, along with the following:

  • Value - The new value, if applicable, for this attribute.

  • Action - A value that specifies how to perform the update. This action is only valid for an existing attribute whose data type is Number or is a set; do not use ADD for other data types.

    If an item with the specified primary key is found in the table, the following values perform the following actions:

    • PUT - Adds the specified attribute to the item. If the attribute already exists, it is replaced by the new value.

    • DELETE - Removes the attribute and its value, if no value is specified for DELETE. The data type of the specified value must match the existing value’s data type.

      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.

    • 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.

        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, with a value of 3.

      • If the existing data type is a set, and if Value is also a set, then Value is appended 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, Value must also be a set of strings.

    If no item with the specified key is found in the table, the following values perform the following actions:

    • PUT - Causes DynamoDB to create a new item with the specified primary key, and then adds the attribute.

    • DELETE - Nothing happens, because attributes cannot be deleted from a nonexistent item. The operation succeeds, but DynamoDB does not create a new item.

    • ADD - Causes DynamoDB to create an item with the supplied primary key and number (or set of numbers) for the attribute value. The only data types allowed are Number and Number Set.

If you provide 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.

@property (nonatomic, strong) NSDictionary<NSString*AWSDynamoDBAttributeValueUpdate*> *attributeUpdates

Declared In

AWSDynamoDBModel.h

  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: = | &#x3C;&#x3E; | &#x3C; | &#x3E; | &#x3C;= | &#x3E;= | BETWEEN | IN

  • Logical operators: AND | OR | NOT

For more information on condition expressions, see Specifying Conditions in the Amazon DynamoDB Developer Guide.

ConditionExpression replaces the legacy ConditionalOperator and Expected parameters.

@property (nonatomic, strong) NSString *conditionExpression

Declared In

AWSDynamoDBModel.h

  conditionalOperator

This is a legacy parameter, for backward compatibility. New applications should use ConditionExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception.

A logical operator to apply to the conditions in the Expected map:

  • AND - If all of the conditions evaluate to true, then the entire map evaluates to true.

  • OR - If at least one of the conditions evaluate to true, then the entire map evaluates to true.

If you omit ConditionalOperator, then AND is the default.

The operation will succeed only if the entire map evaluates to true.

This parameter does not support attributes of type List or Map.

@property (nonatomic, assign) AWSDynamoDBConditionalOperator conditionalOperator

Declared In

AWSDynamoDBModel.h

  expected

This is a legacy parameter, for backward compatibility. New applications should use ConditionExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception.

A map of attribute/condition pairs. Expected provides a conditional block for the UpdateItem operation.

Each element of Expected consists of an attribute name, a comparison operator, and one or more values. DynamoDB compares the attribute with the value(s) you supplied, using the comparison operator. For each Expected element, the result of the evaluation is either true or false.

If you specify more than one element in the Expected map, then by default all of the conditions must evaluate to true. In other words, the conditions are ANDed together. (You can use the ConditionalOperator parameter to OR the conditions instead. If you do this, then at least one of the conditions must evaluate to true, rather than all of them.)

If the Expected map evaluates to true, then the conditional operation succeeds; otherwise, it fails.

Expected contains the following:

  • AttributeValueList - One or more values to evaluate against the supplied attribute. The number of values in the list depends on the ComparisonOperator being used.

    For type Number, value comparisons are numeric.

    String value comparisons for greater than, equals, or less than are based on ASCII character code values. For example, a is greater than A, and a is greater than B. For a list of code values, see http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters.

    For type Binary, DynamoDB treats each byte of the binary data as unsigned when it compares binary values.

  • ComparisonOperator - A comparator for evaluating attributes in the AttributeValueList. When performing the comparison, DynamoDB uses strongly consistent reads.

    The following comparison operators are available:

    EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN

    The following are descriptions of each comparison operator.

    • EQ : Equal. EQ is supported for all datatypes, including lists and maps.

      AttributeValueList can contain only one AttributeValue element of type String, Number, Binary, String Set, Number Set, or Binary Set. If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not equal {“N”:“6”}. Also, {“N”:“6”} does not equal {“NS”:[“6”, “2”, “1”]}.

    • NE : Not equal. NE is supported for all datatypes, including lists and maps.

      AttributeValueList can contain only one AttributeValue of type String, Number, Binary, String Set, Number Set, or Binary Set. If an item contains an AttributeValue of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not equal {“N”:“6”}. Also, {“N”:“6”} does not equal {“NS”:[“6”, “2”, “1”]}.

    • LE : Less than or equal.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not equal {“N”:“6”}. Also, {“N”:“6”} does not compare to {“NS”:[“6”, “2”, “1”]}.

    • LT : Less than.

      AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not equal {“N”:“6”}. Also, {“N”:“6”} does not compare to {“NS”:[“6”, “2”, “1”]}.

    • GE : Greater than or equal.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not equal {“N”:“6”}. Also, {“N”:“6”} does not compare to {“NS”:[“6”, “2”, “1”]}.

    • GT : Greater than.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not equal {“N”:“6”}. Also, {“N”:“6”} does not compare to {“NS”:[“6”, “2”, “1”]}.

    • NOT_NULL : The attribute exists. NOT_NULL is supported for all datatypes, including lists and maps.

      This operator tests for the existence of an attribute, not its data type. If the data type of attribute “a” is null, and you evaluate it using NOT_NULL, the result is a Boolean true. This result is because the attribute “a” exists; its data type is not relevant to the NOT_NULL comparison operator.

    • NULL : The attribute does not exist. NULL is supported for all datatypes, including lists and maps.

      This operator tests for the nonexistence of an attribute, not its data type. If the data type of attribute “a” is null, and you evaluate it using NULL, the result is a Boolean false. This is because the attribute “a” exists; its data type is not relevant to the NULL comparison operator.

    • CONTAINS : Checks for a subsequence, or value in a set.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If the target attribute of the comparison is of type String, then the operator checks for a substring match. If the target attribute of the comparison is of type Binary, then the operator looks for a subsequence of the target that matches the input. If the target attribute of the comparison is a set (“SS”, “NS”, or “BS”), then the operator evaluates to true if it finds an exact match with any member of the set.

      CONTAINS is supported for lists: When evaluating “a CONTAINS b”, “a” can be a list; however, “b” cannot be a set, a map, or a list.

    • NOT_CONTAINS : Checks for absence of a subsequence, or absence of a value in a set.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If the target attribute of the comparison is a String, then the operator checks for the absence of a substring match. If the target attribute of the comparison is Binary, then the operator checks for the absence of a subsequence of the target that matches the input. If the target attribute of the comparison is a set (“SS”, “NS”, or “BS”), then the operator evaluates to true if it does not find an exact match with any member of the set.

      NOT_CONTAINS is supported for lists: When evaluating “a NOT CONTAINS b”, “a” can be a list; however, “b” cannot be a set, a map, or a list.

    • BEGINS_WITH : Checks for a prefix.

      AttributeValueList can contain only one AttributeValue of type String or Binary (not a Number or a set type). The target attribute of the comparison must be of type String or Binary (not a Number or a set type).

    • IN : Checks for matching elements within two sets.

      AttributeValueList can contain one or more AttributeValue elements of type String, Number, or Binary (not a set type). These attributes are compared against an existing set type attribute of an item. If any elements of the input set are present in the item attribute, the expression evaluates to true.

    • BETWEEN : Greater than or equal to the first value, and less than or equal to the second value.

      AttributeValueList must contain two AttributeValue elements of the same type, either String, Number, or Binary (not a set type). A target attribute matches if the target value is greater than, or equal to, the first element and less than, or equal to, the second element. If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {“S”:“6”} does not compare to {“N”:“6”}. Also, {“N”:“6”} does not compare to {“NS”:[“6”, “2”, “1”]}

For usage examples of AttributeValueList and ComparisonOperator, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.

For backward compatibility with previous DynamoDB releases, the following parameters can be used instead of AttributeValueList and ComparisonOperator:

  • Value - A value for DynamoDB to compare with an attribute.

  • Exists - A Boolean value that causes DynamoDB to evaluate the value before attempting the conditional operation:

    • If Exists is true, DynamoDB will check to see if that attribute value already exists in the table. If it is found, then the condition evaluates to true; otherwise the condition evaluate to false.

    • If Exists is false, DynamoDB assumes that the attribute value does not exist in the table. If in fact the value does not exist, then the assumption is valid and the condition evaluates to true. If the value is found, despite the assumption that it does not exist, the condition evaluates to false.

    Note that the default value for Exists is true.

The Value and Exists parameters are incompatible with AttributeValueList and ComparisonOperator. Note that if you use both sets of parameters at once, DynamoDB will return a ValidationException exception.

This parameter does not support attributes of type List or Map.

@property (nonatomic, strong) NSDictionary<NSString*AWSDynamoDBExpectedAttributeValue*> *expected

Declared In

AWSDynamoDBModel.h

  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 Accessing Item Attributes in the Amazon DynamoDB Developer Guide.

@property (nonatomic, strong) NSDictionary<NSString*NSString*> *expressionAttributeNames

Declared In

AWSDynamoDBModel.h

  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 Specifying Conditions in the Amazon DynamoDB Developer Guide.

@property (nonatomic, strong) NSDictionary<NSString*AWSDynamoDBAttributeValue*> *expressionAttributeValues

Declared In

AWSDynamoDBModel.h

  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.

@property (nonatomic, strong) NSDictionary<NSString*AWSDynamoDBAttributeValue*> *key

Declared In

AWSDynamoDBModel.h

  returnConsumedCapacity

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.

@property (nonatomic, assign) AWSDynamoDBReturnConsumedCapacity returnConsumedCapacity

Declared In

AWSDynamoDBModel.h

  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.

@property (nonatomic, assign) AWSDynamoDBReturnItemCollectionMetrics returnItemCollectionMetrics

Declared In

AWSDynamoDBModel.h

  returnValues

Use ReturnValues if you want to get the item attributes as they appeared either before or after they were 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 - If UpdateItem overwrote an attribute name-value pair, then the content of the old item is returned.

  • UPDATED_OLD - The old versions of only the updated attributes are returned.

  • ALL_NEW - All of the attributes of the new version of the item are returned.

  • UPDATED_NEW - The new versions of only the updated attributes are returned.

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.

Values returned are strongly consistent

@property (nonatomic, assign) AWSDynamoDBReturnValue returnValues

Declared In

AWSDynamoDBModel.h

  tableName

The name of the table containing the item to update.

@property (nonatomic, strong) NSString *tableName

Declared In

AWSDynamoDBModel.h

  updateExpression

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.

      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.

UpdateExpression replaces the legacy AttributeUpdates parameter.

@property (nonatomic, strong) NSString *updateExpression

Declared In

AWSDynamoDBModel.h