AvroCoder (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

java.lang.Object
- com.google.cloud.dataflow.sdk.coders.StandardCoder<T>
- - com.google.cloud.dataflow.sdk.coders.AvroCoder<T>

Type Parameters:

T - the type of elements handled by this coder

All Implemented Interfaces:

Coder<T>, Serializable
```
public class AvroCoder<T>
extends StandardCoder<T>
```
A Coder using Avro binary format.
Each instance of AvroCoder<T> encapsulates an Avro schema for objects of type T.
The Avro schema may be provided explicitly via of(Class, Schema) or omitted via of(Class), in which case it will be inferred using Avro's ReflectData.
For complete details about schema generation and how it can be controlled please see the org.apache.avro.reflect package. Only concrete classes with a no-argument constructor can be mapped to Avro records. All inherited fields that are not static or transient are included. Fields are not permitted to be null unless annotated by Nullable or a Union schema containing "null".
To use, specify the Coder type on a PCollection:
```
 
 PCollection<MyCustomElement> records =
     input.apply(...)
          .setCoder(AvroCoder.of(MyCustomElement.class);
 
 
```
or annotate the element class using @DefaultCoder.
```
  @DefaultCoder(AvroCoder.class)
 public class MyCustomElement {
   ...
 }
 
```
The implementation attempts to determine if the Avro encoding of the given type will satisfy the criteria of Coder.verifyDeterministic() by inspecting both the type and the Schema provided or generated by Avro. Only coders that are deterministic can be used in GroupByKey operations.
See Also:

Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from interface com.google.cloud.dataflow.sdk.coders.Coder
  Coder.Context, Coder.NonDeterministicException

Field Summary

Fields
Modifier and Type Field and Description

static CoderProvider PROVIDER

Constructor Summary

Constructors
Modifier Constructor and Description

protected AvroCoder(Class<T> type, Schema schema)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`com.google.cloud.dataflow.sdk.util.CloudObject`	`asCloudObject()` Returns the `CloudObject` that represents this `Coder`.
`DatumReader<T>`	`createDatumReader()` Deprecated. For `AvroCoder` internal use only.
`DatumWriter<T>`	`createDatumWriter()` Deprecated. For `AvroCoder` internal use only.
`T`	`decode(InputStream inStream, Coder.Context context)` Decodes a value of type `T` from the given input stream in the given context.
`void`	`encode(T value, OutputStream outStream, Coder.Context context)` Encodes the given value of type `T` onto the given output stream in the given context.
`List<? extends Coder<?>>`	`getCoderArguments()` If this is a `Coder` for a parameterized type, returns the list of `Coder`s being used for each of the parameters, or returns `null` if this cannot be done or this is not a parameterized type.
`String`	`getEncodingId()` The encoding identifier is designed to support evolution as per the design of Avro In order to use this class effectively, carefully read the Avro documentation at Schema Resolution to ensure that the old and new schema match.
`Schema`	`getSchema()` Returns the schema used by this coder.
`Class<T>`	`getType()` Returns the type this coder encodes/decodes.
`static <T> AvroCoder<T>`	`of(Class<T> clazz)` Returns an `AvroCoder` instance for the provided element class.
`static <T> AvroCoder<T>`	`of(Class<T> type, Schema schema)` Returns an `AvroCoder` instance for the provided element type using the provided Avro schema.
`static AvroCoder<GenericRecord>`	`of(Schema schema)` Returns an `AvroCoder` instance for the Avro schema.
`static AvroCoder<?>`	`of(String classType, String schema)`
`static <T> AvroCoder<T>`	`of(TypeDescriptor<T> type)` Returns an `AvroCoder` instance for the provided element type.
`void`	`verifyDeterministic()` Throw `Coder.NonDeterministicException` if the coding is not deterministic.

Methods inherited from class com.google.cloud.dataflow.sdk.coders.StandardCoder
consistentWithEquals, equals, getAllowedEncodings, getComponents, getEncodedElementByteSize, hashCode, isRegisterByteSizeObserverCheap, registerByteSizeObserver, structuralValue, toString, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - PROVIDER
```
public static final CoderProvider PROVIDER
```
- Constructor Detail
  - AvroCoder
```
protected AvroCoder(Class<T> type,
                    Schema schema)
```
- Method Detail
  - of
```
public static <T> AvroCoder<T> of(TypeDescriptor<T> type)
```
    Returns an AvroCoder instance for the provided element type.
    
    Type Parameters:
    
    T - the element type
  - of
```
public static <T> AvroCoder<T> of(Class<T> clazz)
```
    Returns an AvroCoder instance for the provided element class.
    
    Type Parameters:
    
    T - the element type
  - of
```
public static AvroCoder<GenericRecord> of(Schema schema)
```
    Returns an AvroCoder instance for the Avro schema. The implicit type is GenericRecord.
  - of
```
public static <T> AvroCoder<T> of(Class<T> type,
                                  Schema schema)
```
    Returns an AvroCoder instance for the provided element type using the provided Avro schema.
    If the type argument is GenericRecord, the schema may be arbitrary. Otherwise, the schema must correspond to the type provided.
    
    Type Parameters:
    
    T - the element type
  - of
```
public static AvroCoder<?> of(String classType,
                              String schema)
                       throws ClassNotFoundException
```
    Throws:
    
    ClassNotFoundException
  - getEncodingId
```
public String getEncodingId()
```
    The encoding identifier is designed to support evolution as per the design of Avro In order to use this class effectively, carefully read the Avro documentation at Schema Resolution to ensure that the old and new schema match.
    In particular, this encoding identifier is guaranteed to be the same for AvroCoder instances of the same principal class, and otherwise distinct. The schema is not included in the identifier.
    When modifying a class to be encoded as Avro, here are some guidelines; see the above link for greater detail.
    - Avoid changing field names.
    - Never remove a required field.
    - Only add optional fields, with sensible defaults.
    - When changing the type of a field, consult the Avro documentation to ensure the new and old types are interchangeable.
    Code consuming this message class should be prepared to support all versions of the class until it is certain that no remaining serialized instances exist.
    If backwards incompatible changes must be made, the best recourse is to change the name of your class.
    Specified by:
    
    getEncodingId in interface Coder<T>
    
    Overrides:
    
    getEncodingId in class StandardCoder<T>
  - getType
```
public Class<T> getType()
```
    Returns the type this coder encodes/decodes.
  - encode
```
public void encode(T value,
                   OutputStream outStream,
                   Coder.Context context)
            throws IOException
```
    Description copied from interface: Coder
    
    Encodes the given value of type T onto the given output stream in the given context.
    
    Throws:
    
    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(InputStream inStream,
                Coder.Context context)
         throws IOException
```
    Description copied from interface: Coder
    
    Decodes a value of type T from the given input stream in the given context. Returns the decoded value.
    
    Throws:
    
    IOException - if reading from the InputStream fails for some reason
    
    CoderException - if the value could not be decoded for some reason
  - getCoderArguments
```
public List<? extends Coder<?>> getCoderArguments()
```
    Description copied from interface: Coder
    
    If this is a Coder for a parameterized type, returns the list of Coders being used for each of the parameters, or returns null if this cannot be done or this is not a parameterized type.
  - asCloudObject
```
public com.google.cloud.dataflow.sdk.util.CloudObject asCloudObject()
```
    Description copied from interface: Coder
    
    Returns the CloudObject that represents this Coder.
    
    Specified by:
    
    asCloudObject in interface Coder<T>
    
    Overrides:
    
    asCloudObject in class StandardCoder<T>
  - verifyDeterministic
```
public void verifyDeterministic()
                         throws Coder.NonDeterministicException
```
    Description copied from interface: Coder
    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.
    Throws:
    
    NonDeterministicException - when the type may not be deterministically encoded using the given Schema, the directBinaryEncoder, and the ReflectDatumWriter or GenericDatumWriter.
    
    Coder.NonDeterministicException - if this coder is not deterministic.
  - createDatumReader
```
@Deprecated
public DatumReader<T> createDatumReader()
```
    Deprecated. For AvroCoder internal use only.
    
    Returns a new DatumReader that can be used to read from an Avro file directly. Assumes the schema used to read is the same as the schema that was used when writing.
  - createDatumWriter
```
@Deprecated
public DatumWriter<T> createDatumWriter()
```
    Deprecated. For AvroCoder internal use only.
    
    Returns a new DatumWriter that can be used to write to an Avro file directly.
  - getSchema
```
public Schema getSchema()
```
    Returns the schema used by this coder.

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Last updated October 11, 2018.

AvroCoder (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Class AvroCoder<T>

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.cloud.dataflow.sdk.coders.Coder

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.google.cloud.dataflow.sdk.coders.StandardCoder

Methods inherited from class java.lang.Object

Field Detail

PROVIDER

Constructor Detail

AvroCoder

Method Detail

of

of

of

of

of

getEncodingId

getType

encode

decode

getCoderArguments

asCloudObject

verifyDeterministic

createDatumReader

createDatumWriter

getSchema

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