software.amazon.awssdk.enhanced.dynamodb

Class Expression

java.lang.Object

software.amazon.awssdk.enhanced.dynamodb.Expression

@ThreadSafe
public final class Expression
extends Object

High-level representation of a DynamoDB 'expression' that can be used in various situations where the API requires or accepts an expression. In addition various convenience methods are provided to help manipulate expressions.

At a minimum, an expression must contain a string that is the expression itself.

Optionally, attribute names can be substituted with tokens using the '#name_token' syntax; also attribute values can be substituted with tokens using the ':value_token' syntax. If tokens are used in the expression then the values or names associated with those tokens must be explicitly added to the expressionValues and expressionNames maps respectively that are also stored on this object.

Example:- Expression myExpression = Expression.builder() .expression("#a = :b") .putExpressionName("#a", "myAttribute") .putExpressionValue(":b", myAttributeValue) .build();

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Expression.Builder A builder for Expression

Method Summary

Modifier and Type	Method and Description
Expression	and(Expression expression) Coalesces two complete expressions into a single expression joined by an 'AND'.
static Expression.Builder	builder() Constructs a new expression builder.
boolean	equals(Object o)
String	expression()
Map<String,String>	expressionNames()
Map<String,AttributeValue>	expressionValues()
int	hashCode()
static Expression	join(Expression expression1, Expression expression2, String joinToken) Coalesces two complete expressions into a single expression.
static String	joinExpressions(String expression1, String expression2, String joinToken) Coalesces two expression strings into a single expression string.
static Map<String,String>	joinNames(Map<String,String> expressionNames1, Map<String,String> expressionNames2) Coalesces two ExpressionNames maps into a single ExpressionNames map.
static Map<String,AttributeValue>	joinValues(Map<String,AttributeValue> expressionValues1, Map<String,AttributeValue> expressionValues2) Coalesces two ExpressionValues maps into a single ExpressionValues map.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Method Detail

builder

public static Expression.Builder builder()

Constructs a new expression builder.

Returns:

a new expression builder.

join

public static Expression join(Expression expression1,
                              Expression expression2,
                              String joinToken)

Coalesces two complete expressions into a single expression. The expression string will be joined using the supplied join token, and the ExpressionNames and ExpressionValues maps will be merged.

Parameters:

expression1 - The first expression to coalesce

expression2 - The second expression to coalesce

joinToken - The join token to be used to join the expression strings (e.g.: 'AND', 'OR')

Returns:

The coalesced expression

Throws:

IllegalArgumentException - if a conflict occurs when merging ExpressionNames or ExpressionValues

joinExpressions

public static String joinExpressions(String expression1,
                                     String expression2,
                                     String joinToken)

Coalesces two expression strings into a single expression string. The expression string will be joined using the supplied join token.

Parameters:

expression1 - The first expression string to coalesce

expression2 - The second expression string to coalesce

joinToken - The join token to be used to join the expression strings (e.g.: 'AND', 'OR)

Returns:

The coalesced expression

joinValues

public static Map<String,AttributeValue> joinValues(Map<String,AttributeValue> expressionValues1,
                                                    Map<String,AttributeValue> expressionValues2)

Coalesces two ExpressionValues maps into a single ExpressionValues map. The ExpressionValues map is an optional component of an expression.

Parameters:

expressionValues1 - The first ExpressionValues map

expressionValues2 - The second ExpressionValues map

Returns:

The coalesced ExpressionValues map

Throws:

IllegalArgumentException - if a conflict occurs when merging ExpressionValues

joinNames

public static Map<String,String> joinNames(Map<String,String> expressionNames1,
                                           Map<String,String> expressionNames2)

Coalesces two ExpressionNames maps into a single ExpressionNames map. The ExpressionNames map is an optional component of an expression.

Parameters:

expressionNames1 - The first ExpressionNames map

expressionNames2 - The second ExpressionNames map

Returns:

The coalesced ExpressionNames map

Throws:

IllegalArgumentException - if a conflict occurs when merging ExpressionNames

expression

public String expression()

expressionValues

public Map<String,AttributeValue> expressionValues()

expressionNames

public Map<String,String> expressionNames()

and

public Expression and(Expression expression)

Coalesces two complete expressions into a single expression joined by an 'AND'.

See Also:

join(Expression, Expression, String)

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object