org.kitesdk.data.spi

Class DataModelUtil

java.lang.Object

org.kitesdk.data.spi.DataModelUtil

public class DataModelUtil
extends Object

Utilities for determining the appropriate data model at runtime.

Since:

0.15.0

Constructor Summary

Constructors

Constructor and Description
DataModelUtil()

Method Summary

Methods

Modifier and Type	Method and Description
static <E> EntityAccessor<E>	accessor(Class<E> type, Schema schema)
static <E> E	createRecord(Class<E> type, Schema schema) If E implements GenericRecord, but does not implement SpecificRecord, then create a new instance of E using reflection so that GenericDataumReader will use the expected type.
static <E> GenericData	getDataModelForType(Class<E> type) Get the data model for the given type.
static <E> DatumReader<E>	getDatumReaderForType(Class<E> type, Schema writerSchema) Get the DatumReader for the given type.
static <E> Schema	getReaderSchema(Class<E> type, Schema schema) Get the reader schema based on the given type and writer schema.
static <E> Schema	getWriterSchema(Class<E> type, Schema schema) Get the writer schema based on the given type and dataset schema.
static boolean	isGeneric(Class<?> type) Test whether the class is a generic GenericRecord and not a SpecificRecord.
static <E> Class<E>	resolveType(Class<E> type, Schema schema) Resolves the type based on the given schema.

Methods inherited from class java.lang.Object

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

Constructor Detail

DataModelUtil

public DataModelUtil()

Method Detail

getDataModelForType

public static <E> GenericData getDataModelForType(Class<E> type)

Get the data model for the given type.

Type Parameters:

E - The entity type

Parameters:

type - The Java class of the entity type

Returns:

The appropriate data model for the given type

isGeneric

public static boolean isGeneric(Class<?> type)

Test whether the class is a generic GenericRecord and not a SpecificRecord. This is necessary instead of testing if GenericRecord is assignable from the class because SpecificRecordBase implements GenericRecord.

Parameters:

type - a Java class

Returns:

true if the class is an Avro generic and not specific

getDatumReaderForType

public static <E> DatumReader<E> getDatumReaderForType(Class<E> type,
                                       Schema writerSchema)

Get the DatumReader for the given type.

Type Parameters:

E - The entity type

Parameters:

type - The Java class of the entity type

writerSchema - The Schema for entities

Returns:

The DatumReader for the given type

resolveType

public static <E> Class<E> resolveType(Class<E> type,
                       Schema schema)

Resolves the type based on the given schema. In most cases, the type should stay as is. However, if the type is Object, then that means that the old default behavior of determining the class from ReflectData#getClass(Schema) should be used. If a class can't be found, it will default to GenericData.Record.

Type Parameters:

E - The entity type

Parameters:

type - The Java class of the entity type

schema - The Schema for the entity

Returns:

The resolved Java class object

getReaderSchema

public static <E> Schema getReaderSchema(Class<E> type,
                         Schema schema)

Get the reader schema based on the given type and writer schema.

Type Parameters:

E - The entity type

Parameters:

type - The Java class of the entity type

schema - The Schema for the entity

Returns:

The reader schema based on the given type and writer schema

getWriterSchema

public static <E> Schema getWriterSchema(Class<E> type,
                         Schema schema)

Get the writer schema based on the given type and dataset schema.

Type Parameters:

E - The entity type

Parameters:

type - The Java class of the entity type

schema - The Schema for the entity

Returns:

The reader schema based on the given type and writer schema

createRecord

public static <E> E createRecord(Class<E> type,
                 Schema schema)

If E implements GenericRecord, but does not implement SpecificRecord, then create a new instance of E using reflection so that GenericDataumReader will use the expected type. Implementations of GenericRecord that require a Schema parameter in the constructor should implement SpecificData.SchemaConstructable. Otherwise, your implementation must have a no-args constructor.

Type Parameters:

E - The entity type

Parameters:

type - The Java class of the entity type

schema - The reader schema

Returns:

An instance of E, or null if the data model is specific or reflect

accessor

public static <E> EntityAccessor<E> accessor(Class<E> type,
                             Schema schema)