AWS SDK for .NET Documentation
ExpectedAttributeValue Class
AmazonAmazon.DynamoDBv2.ModelExpectedAttributeValue Did this page help you?   Yes   No    Tell us about it...

Represents an attribute value used with conditional DeleteItem , PutItem or UpdateItem operations. DynamoDB will check to see if the attribute value already exists; or if the attribute exists and has a particular value before updating it.

Declaration Syntax
C#
public class ExpectedAttributeValue
Members
All MembersConstructorsMethodsProperties



IconMemberDescription
ExpectedAttributeValue()()()()
Initializes a new instance of the ExpectedAttributeValue class

AttributeValueList
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 aa is greater than B. For a list of code values, see http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters. For Binary, DynamoDB treats each byte of the binary data as unsigned when it compares binary values, for example when evaluating query expressions. For information on specifying data types in JSON, see JSON Data Format in the Amazon DynamoDB Developer Guide.
Note:
You cannot specify AttributeValueList if Exists or Value are also present.

ComparisonOperator
A comparator for evaluating attributes in the AttributeValueList. For example, equals, greater than, less than, etc. The following comparison operators are available: EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN
Note:
You cannot specify ComparisonOperator if Exists or Value are also present.
The following are descriptions of each comparison operator.
  • EQ : Equal. AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set). If an item contains an AttributeValue of a different type than the one specified 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. AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set). If an item contains an AttributeValue of a different type than the one specified 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 of type String, Number, or Binary (not a set). If an item contains an AttributeValue of a different type than the one specified 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). If an item contains an AttributeValue of a different type than the one specified 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 of type String, Number, or Binary (not a set). If an item contains an AttributeValue of a different type than the one specified 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 of type String, Number, or Binary (not a set). If an item contains an AttributeValue of a different type than the one specified 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.
  • NULL : The attribute does not exist.
  • CONTAINS : checks for a subsequence, or value in a set. AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set). If the target attribute of the comparison is a String, then the operation checks for a substring match. If the target attribute of the comparison is Binary, then the operation 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 operation checks for a member of the set (not as a substring).
  • NOT_CONTAINS : checks for absence of a subsequence, or absence of a value in a set. AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set). If the target attribute of the comparison is a String, then the operation checks for the absence of a substring match. If the target attribute of the comparison is Binary, then the operation 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 operation checks for the absence of a member of the set (not as a substring).
  • BEGINS_WITH : checks for a prefix. AttributeValueList can contain only one AttributeValue of type String or Binary (not a Number or a set). The target attribute of the comparison must be a String or Binary (not a Number or a set).

  • IN : checks for exact matches. AttributeValueList can contain more than one AttributeValue of type String, Number, or Binary (not a set). The target attribute of the comparison must be of the same type and exact value to match. A String never matches a String set.
  • 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). 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 of a different type than the one specified 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"]}

Constraints:

Allowed Values
EQ, NE, IN, LE, LT, GE, GT, BETWEEN, NOT_NULL, NULL, CONTAINS, NOT_CONTAINS, BEGINS_WITH


Equals(Object)
Determines whether the specified Object is equal to the current Object.
(Inherited from Object.)
Exists
Causes DynamoDB to evaluate the value before attempting a 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 operation succeeds. If it is not found, the operation fails with a ConditionalCheckFailedException.
  • 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 operation succeeds. If the value is found, despite the assumption that it does not exist, the operation fails with a ConditionalCheckFailedException.
The default setting for Exists is true. If you supply a Value all by itself, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied. DynamoDB returns a ValidationException if:
  • Exists is true but there is no Value to check. (You expect a value to exist, but don't specify what that value is.)
  • Exists is false but you also specify a Value. (You cannot expect an attribute to have a value, while also expecting it not to exist.)

GetHashCode()()()()
Serves as a hash function for a particular type.
(Inherited from Object.)
GetType()()()()
Gets the type of the current instance.
(Inherited from Object.)
ToString()()()()
Returns a string that represents the current object.
(Inherited from Object.)
Value
Represents the data for an attribute. You can set one, and only one, of the elements.

WithAttributeValueList(array<AttributeValue>[]()[][]) Obsolete.
Adds elements to the AttributeValueList collection

WithAttributeValueList(IEnumerable<(Of <<'(AttributeValue>)>>)) Obsolete.
Adds elements to the AttributeValueList collection

WithComparisonOperator(String) Obsolete.
Sets the ComparisonOperator property

WithExists(Boolean) Obsolete.
Sets the Exists property

WithValue(AttributeValue) Obsolete.
Sets the Value property

Inheritance Hierarchy
Object
ExpectedAttributeValue

Assembly: AWSSDK (Module: AWSSDK) Version: 1.5.60.0 (1.5.60.0)