org.apache.beam.sdk.schemas

Class SchemaCoder<T>

java.lang.Object

org.apache.beam.sdk.coders.Coder<T>

org.apache.beam.sdk.coders.CustomCoder<T>

org.apache.beam.sdk.schemas.SchemaCoder<T>

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

RowCoder

public class SchemaCoder<T>
extends CustomCoder<T>

SchemaCoder is used as the coder for types that have schemas registered.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.beam.sdk.coders.Coder

Coder.Context, Coder.NonDeterministicException

Field Summary

Fields

Modifier and Type	Field and Description
protected Schema	schema

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SchemaCoder(Schema schema, TypeDescriptor<T> typeDescriptor, SerializableFunction<T,Row> toRowFunction, SerializableFunction<Row,T> fromRowFunction)

Method Summary

Modifier and Type	Method and Description
static <T> Coder<T>	coderForFieldType(Schema.FieldType fieldType)
boolean	consistentWithEquals() Returns true if this Coder is injective with respect to Object.equals(java.lang.Object).
T	decode(java.io.InputStream inStream) Decodes a value of type T from the given input stream in the given context.
void	encode(T value, java.io.OutputStream outStream) Encodes the given value of type T onto the given output stream.
boolean	equals(@Nullable java.lang.Object o)
TypeDescriptor<T>	getEncodedTypeDescriptor() Returns the TypeDescriptor for the type encoded.
SerializableFunction<Row,T>	getFromRowFunction() Returns the toRow conversion function.
Schema	getSchema() Returns the schema associated with this type.
SerializableFunction<T,Row>	getToRowFunction() Returns the fromRow conversion function.
int	hashCode()
static SchemaCoder<Row>	of(Schema schema) Returns a SchemaCoder for Row instances with the given schema.
static <T> SchemaCoder<T>	of(Schema schema, TypeDescriptor<T> typeDescriptor, SerializableFunction<T,Row> toRowFunction, SerializableFunction<Row,T> fromRowFunction) Returns a SchemaCoder for the specified class.
static void	overrideEncodingPositions(java.util.UUID uuid, java.util.Map<java.lang.String,java.lang.Integer> encodingPositions) Override encoding positions for the given schema.
java.lang.String	toString()
void	verifyDeterministic() Throw Coder.NonDeterministicException if the coding is not deterministic.

Methods inherited from class org.apache.beam.sdk.coders.CustomCoder

getCoderArguments

Methods inherited from class org.apache.beam.sdk.coders.Coder

decode, encode, getEncodedElementByteSize, isRegisterByteSizeObserverCheap, registerByteSizeObserver, structuralValue, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object

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

Field Detail

schema

protected final Schema schema

Constructor Detail

SchemaCoder

protected SchemaCoder(Schema schema,
                      TypeDescriptor<T> typeDescriptor,
                      SerializableFunction<T,Row> toRowFunction,
                      SerializableFunction<Row,T> fromRowFunction)

Method Detail

of

public static <T> SchemaCoder<T> of(Schema schema,
                                    TypeDescriptor<T> typeDescriptor,
                                    SerializableFunction<T,Row> toRowFunction,
                                    SerializableFunction<Row,T> fromRowFunction)

Returns a SchemaCoder for the specified class. If no schema is registered for this class, then throws NoSuchSchemaException. The parameter functions to convert from and to Rows must implement the equals contract.

of

public static SchemaCoder<Row> of(Schema schema)

Returns a SchemaCoder for Row instances with the given schema.

overrideEncodingPositions

public static void overrideEncodingPositions(java.util.UUID uuid,
                                             java.util.Map<java.lang.String,java.lang.Integer> encodingPositions)

Override encoding positions for the given schema.

getSchema

public Schema getSchema()

Returns the schema associated with this type.

getFromRowFunction

public SerializableFunction<Row,T> getFromRowFunction()

Returns the toRow conversion function.

getToRowFunction

public SerializableFunction<T,Row> getToRowFunction()

Returns the fromRow conversion function.

encode

public void encode(T value,
                   java.io.OutputStream outStream)
            throws java.io.IOException

Description copied from class: Coder

Encodes the given value of type T onto the given output stream. Multiple elements can be encoded next to each other on the output stream, each coder should encode information to know how many bytes to read when decoding. A common approach is to prefix the encoding with the element's encoded length.

Specified by:

encode in class Coder<T>

Throws:

java.io.IOException - if writing to the OutputStream fails for some reason

CoderException - if the value could not be encoded for some reason

decode

public T decode(java.io.InputStream inStream)
         throws java.io.IOException

Description copied from class: Coder

Decodes a value of type T from the given input stream in the given context. Returns the decoded value. Multiple elements can be encoded next to each other on the input stream, each coder should encode information to know how many bytes to read when decoding. A common approach is to prefix the encoding with the element's encoded length.

Specified by:

decode in class Coder<T>

Throws:

java.io.IOException - if reading from the InputStream fails for some reason

CoderException - if the value could not be decoded for some reason

verifyDeterministic

public void verifyDeterministic()
                         throws Coder.NonDeterministicException

Description copied from class: CustomCoder

Throw Coder.NonDeterministicException if the coding is not deterministic.

In order for a Coder to be considered deterministic, the following must be true:

• two values that compare as equal (via Object.equals() or Comparable.compareTo(), if supported) have the same encoding.
• the Coder always produces a canonical encoding, which is the same for an instance of an object even if produced on different computers at different times.

Overrides:

verifyDeterministic in class CustomCoder<T>

Throws:

Coder.NonDeterministicException - if this coder is not deterministic.

consistentWithEquals

public boolean consistentWithEquals()

Description copied from class: Coder

Returns true if this Coder is injective with respect to Object.equals(java.lang.Object).

Whenever the encoded bytes of two values are equal, then the original values are equal according to Objects.equals(). Note that this is well-defined for null.

This condition is most notably false for arrays. More generally, this condition is false whenever equals() compares object identity, rather than performing a semantic/structural comparison.

By default, returns false.

Overrides:

consistentWithEquals in class Coder<T>

coderForFieldType

public static <T> Coder<T> coderForFieldType(Schema.FieldType fieldType)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

equals

public boolean equals(@Nullable java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getEncodedTypeDescriptor

public TypeDescriptor<T> getEncodedTypeDescriptor()

Description copied from class: Coder

Returns the TypeDescriptor for the type encoded.

Overrides:

getEncodedTypeDescriptor in class Coder<T>