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:
  • Method Details

    • 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()
      Description copied from interface: ToCopyableBuilder
      Take this object and create a builder that contains all of the current property values of this object.
      Specified by:
      toBuilder in interface ToCopyableBuilder<KeysAndAttributes.Builder,KeysAndAttributes>
      Returns:
      a builder for type T
    • 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)
      Description copied from interface: SdkPojo
      Indicates whether some other object is "equal to" this one by SDK fields. An SDK field is a modeled, non-inherited field in an SdkPojo class, and is generated based on a service model.

      If an SdkPojo class does not have any inherited fields, equalsBySdkFields and equals are essentially the same.

      Specified by:
      equalsBySdkFields in interface SdkPojo
      Parameters:
      obj - the object to be compared with
      Returns:
      true if the other object equals to this object by sdk fields, false otherwise.
    • 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
      Returns:
      List of SdkField in this POJO. May be empty list but should never be null.