software.amazon.awssdk.extensions.dynamodb.mappingclient

Interface TableSchema<T>

Type Parameters:

T - The type of model object that is being mapped to records in the DynamoDb table.

All Known Implementing Classes:

StaticTableSchema

public interface TableSchema<T>

Interface for a mapper that is capable of mapping a modelled Java object into a map of AttributeValue that is understood by the DynamoDb low-level SDK and back again. This object is also expected to know about the structure of the table it is modelling, which is stored in a TableMetadata object.

Method Summary

Modifier and Type	Method and Description
AttributeValue	attributeValue(T item, String key) Returns a single attribute value from the modelled object.
Map<String,AttributeValue>	itemToMap(T item, boolean ignoreNulls) Takes a modelled object and converts it into a raw map of AttributeValue that the DynamoDb low-level SDK can work with.
Map<String,AttributeValue>	itemToMap(T item, Collection<String> attributes) Takes a modelled object and extracts a specific set of attributes which are then returned as a map of AttributeValue that the DynamoDb low-level SDK can work with.
T	mapToItem(Map<String,AttributeValue> attributeMap) Takes a raw DynamoDb SDK representation of a record in a table and maps it to a Java object.
TableMetadata	tableMetadata() Returns the object that describes the structure of the table being modelled by the mapper.

Method Detail

mapToItem

T mapToItem(Map<String,AttributeValue> attributeMap)

Takes a raw DynamoDb SDK representation of a record in a table and maps it to a Java object. A new object is created to fulfil this operation.

If attributes are missing from the map, that will not cause an error, however if attributes are found in the map which the mapper does not know how to map, an exception will be thrown.

Parameters:

attributeMap - A map of String to AttributeValue that contains all the raw attributes to map.

Returns:

A new instance of a Java object with all the attributes mapped onto it.

Throws:

IllegalArgumentException - if any attributes in the map could not be mapped onto the new model object.

itemToMap

Map<String,AttributeValue> itemToMap(T item,
                                     boolean ignoreNulls)

Takes a modelled object and converts it into a raw map of AttributeValue that the DynamoDb low-level SDK can work with.

Parameters:

item - The modelled Java object to convert into a map of attributes.

ignoreNulls - If set to true; any null values in the Java object will not be added to the output map. If set to false; null values in the Java object will be added as AttributeValue of type 'nul' to the output map.

Returns:

A map of String to AttributeValue representing all the modelled attributes in the model object.

itemToMap

Map<String,AttributeValue> itemToMap(T item,
                                     Collection<String> attributes)

Takes a modelled object and extracts a specific set of attributes which are then returned as a map of AttributeValue that the DynamoDb low-level SDK can work with. This method is typically used to extract just the key attributes of a modelled item and will not ignore nulls on the modelled object.

Parameters:

item - The modelled Java object to extract the map of attributes from.

attributes - A collection of attribute names to extract into the output map.

Returns:

A map of String to AttributeValue representing the requested modelled attributes in the model object.

attributeValue

AttributeValue attributeValue(T item,
                              String key)

Returns a single attribute value from the modelled object.

Parameters:

item - The modelled Java object to extract the attribute from.

key - The attribute name describing which attribute to extract.

Returns:

A single AttributeValue representing the requested modelled attribute in the model object or null if the attribute has not been set with a value in the modelled object.

tableMetadata

TableMetadata tableMetadata()

Returns the object that describes the structure of the table being modelled by the mapper. This includes information such as the table name, index keys and attribute tags.

Returns:

A TableMetadata object that contains structural information about the table being modelled.