Package software.amazon.awssdk.services.dynamodb.model

Class KeysAndAttributes

java.lang.Object

software.amazon.awssdk.services.dynamodb.model.KeysAndAttributes

All Implemented Interfaces:

Serializable, SdkPojo, ToCopyableBuilder<KeysAndAttributes.Builder,KeysAndAttributes>

@Generated("software.amazon.awssdk:codegen")
public final class KeysAndAttributes
extends Object
implements SdkPojo, Serializable, ToCopyableBuilder<KeysAndAttributes.Builder,KeysAndAttributes>

Represents a set of primary keys and, for each key, the attributes to retrieve from the table.

For each primary key, you must provide all of the key attributes. For example, with a simple primary key, you only need to provide the partition key. For a composite primary key, you must provide both the partition key and the sort key.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	KeysAndAttributes.Builder

Method Summary

Modifier and Type	Method	Description
List<String>	attributesToGet()	This is a legacy parameter.
static KeysAndAttributes.Builder	builder()
Boolean	consistentRead()	The consistency of a read operation.
boolean	equals(Object obj)
boolean	equalsBySdkFields(Object obj)
Map<String,String>	expressionAttributeNames()	One or more substitution tokens for attribute names in an expression.
<T> Optional<T>	getValueForField(String fieldName, Class<T> clazz)
boolean	hasAttributesToGet()	For responses, this returns true if the service returned a value for the AttributesToGet property.
boolean	hasExpressionAttributeNames()	For responses, this returns true if the service returned a value for the ExpressionAttributeNames property.
int	hashCode()
boolean	hasKeys()	For responses, this returns true if the service returned a value for the Keys property.
List<Map<String,AttributeValue>>	keys()	The primary key attribute values that define the items and the attributes associated with the items.
String	projectionExpression()	A string that identifies one or more attributes to retrieve from the table.
List<SdkField<?>>	sdkFields()
static Class<? extends KeysAndAttributes.Builder>	serializableBuilderClass()
KeysAndAttributes.Builder	toBuilder()
String	toString()	Returns a string representation of this object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface software.amazon.awssdk.utils.builder.ToCopyableBuilder

copy

Method Detail

hasKeys

public final boolean hasKeys()

For responses, this returns true if the service returned a value for the Keys property. This DOES NOT check that the value is non-empty (for which, you should check the isEmpty() method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.

keys

public final List<Map<String,AttributeValue>> keys()

The primary key attribute values that define the items and the attributes associated with the items.

Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.

This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the hasKeys() method.

Returns:

The primary key attribute values that define the items and the attributes associated with the items.

hasAttributesToGet

public final boolean hasAttributesToGet()

For responses, this returns true if the service returned a value for the AttributesToGet property. This DOES NOT check that the value is non-empty (for which, you should check the isEmpty() method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.

attributesToGet

public final List<String> attributesToGet()

This is a legacy parameter. Use ProjectionExpression instead. For more information, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.

Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.

This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the hasAttributesToGet() method.

Returns:

This is a legacy parameter. Use ProjectionExpression instead. For more information, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.

consistentRead

public final Boolean consistentRead()

The consistency of a read operation. If set to true, then a strongly consistent read is used; otherwise, an eventually consistent read is used.

Returns:

The consistency of a read operation. If set to true, then a strongly consistent read is used; otherwise, an eventually consistent read is used.

projectionExpression

public final String projectionExpression()

A string that identifies one or more attributes to retrieve from the table. These attributes can include scalars, sets, or elements of a JSON document. The attributes in the ProjectionExpression must be separated by commas.

If no attribute names are specified, then all attributes will be returned. If any of the requested attributes are not found, they will not appear in the result.

For more information, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.

Returns:

A string that identifies one or more attributes to retrieve from the table. These attributes can include scalars, sets, or elements of a JSON document. The attributes in the ProjectionExpression must be separated by commas.

If no attribute names are specified, then all attributes will be returned. If any of the requested attributes are not found, they will not appear in the result.

For more information, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.

hasExpressionAttributeNames

public final boolean hasExpressionAttributeNames()

For responses, this returns true if the service returned a value for the ExpressionAttributeNames property. This DOES NOT check that the value is non-empty (for which, you should check the isEmpty() method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.

expressionAttributeNames

public final Map<String,String> 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.

Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.

This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the hasExpressionAttributeNames() method.

Returns:

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.

toBuilder

public KeysAndAttributes.Builder toBuilder()

Specified by:

toBuilder in interface ToCopyableBuilder<KeysAndAttributes.Builder,KeysAndAttributes>

builder

public static KeysAndAttributes.Builder builder()

serializableBuilderClass

public static Class<? extends KeysAndAttributes.Builder> serializableBuilderClass()

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

equals

public final boolean equals(Object obj)

Overrides:

equals in class Object

equalsBySdkFields

public final boolean equalsBySdkFields(Object obj)

Specified by:

equalsBySdkFields in interface SdkPojo

toString

public final String toString()

Returns a string representation of this object. This is useful for testing and debugging. Sensitive data will be redacted from this string using a placeholder value.

Overrides:

toString in class Object

getValueForField

public final <T> Optional<T> getValueForField(String fieldName,
                                              Class<T> clazz)

sdkFields

public final List<SdkField<?>> sdkFields()

Specified by:

sdkFields in interface SdkPojo