public class MapElements<InputT,OutputT> extends PTransform<PCollection<? extends InputT>,PCollection<OutputT>>
PTransform
s for mapping a simple function over the elements of a PCollection
.Modifier and Type | Class and Description |
---|---|
static class |
MapElements.MapWithFailures<InputT,OutputT,FailureT>
A
PTransform that adds exception handling to MapElements . |
annotations, displayData, name, resourceHints
Modifier and Type | Method and Description |
---|---|
<NewFailureT> |
exceptionsInto(TypeDescriptor<NewFailureT> failureTypeDescriptor)
Returns a new
MapElements.MapWithFailures transform that catches exceptions raised while mapping
elements, with the given type descriptor used for the failure collection but the exception
handler yet to be specified using MapElements.MapWithFailures.exceptionsVia(ProcessFunction) . |
<FailureT> MapElements.MapWithFailures<InputT,OutputT,FailureT> |
exceptionsVia(InferableFunction<WithFailures.ExceptionElement<InputT>,FailureT> exceptionHandler)
Returns a new
MapElements.MapWithFailures transform that catches exceptions raised while mapping
elements, passing the raised exception instance and the input element being processed through
the given exceptionHandler and emitting the result to a failure collection. |
PCollection<OutputT> |
expand(PCollection<? extends InputT> input)
Override this method to specify how this
PTransform should be expanded on the given
InputT . |
static <OutputT> MapElements<?,OutputT> |
into(TypeDescriptor<OutputT> outputType)
Returns a new
MapElements transform with the given type descriptor for the output type,
but the mapping function yet to be specified using via(ProcessFunction) . |
void |
populateDisplayData(DisplayData.Builder builder)
Register display data for the given transform or component.
|
<NewInputT> |
via(Contextful<Contextful.Fn<NewInputT,OutputT>> fn)
Like
via(ProcessFunction) , but supports access to context, such as side inputs. |
static <InputT,OutputT> |
via(InferableFunction<InputT,OutputT> fn)
For
InferableFunction<InputT, OutputT> fn , returns a PTransform that
takes an input PCollection<InputT> and returns a PCollection<OutputT>
containing fn.apply(v) for every element v in the input. |
<NewInputT> |
via(ProcessFunction<NewInputT,OutputT> fn)
For a
ProcessFunction<InputT, OutputT> fn and output type descriptor, returns a
PTransform that takes an input PCollection<InputT> and returns a PCollection<OutputT> containing fn.apply(v) for every element v in the input. |
<NewInputT> |
via(SerializableFunction<NewInputT,OutputT> fn)
Binary compatibility adapter for
via(ProcessFunction) . |
static <InputT,OutputT> |
via(SimpleFunction<InputT,OutputT> fn)
Binary compatibility adapter for
via(InferableFunction) . |
addAnnotation, compose, compose, getAdditionalInputs, getAnnotations, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, getResourceHints, setDisplayData, setResourceHints, toString, validate, validate
public static <InputT,OutputT> MapElements<InputT,OutputT> via(InferableFunction<InputT,OutputT> fn)
InferableFunction<InputT, OutputT>
fn
, returns a PTransform
that
takes an input PCollection<InputT>
and returns a PCollection<OutputT>
containing fn.apply(v)
for every element v
in the input.
InferableFunction
has the advantage of providing type descriptor information, but it
is generally more convenient to specify output type via into(TypeDescriptor)
, and
provide the mapping as a lambda expression to via(ProcessFunction)
.
Example usage:
PCollection<String> words = ...;
PCollection<Integer> wordsPerLine = words.apply(MapElements.via(
new InferableFunction<String, Integer>() {
public Integer apply(String word) throws Exception {
return word.length();
}
}));
public static <InputT,OutputT> MapElements<InputT,OutputT> via(SimpleFunction<InputT,OutputT> fn)
via(InferableFunction)
.public static <OutputT> MapElements<?,OutputT> into(TypeDescriptor<OutputT> outputType)
MapElements
transform with the given type descriptor for the output type,
but the mapping function yet to be specified using via(ProcessFunction)
.public <NewInputT> MapElements<NewInputT,OutputT> via(ProcessFunction<NewInputT,OutputT> fn)
ProcessFunction<InputT, OutputT>
fn
and output type descriptor, returns a
PTransform
that takes an input PCollection<InputT>
and returns a PCollection<OutputT>
containing fn.apply(v)
for every element v
in the input.
Example usage:
PCollection<Integer> wordLengths = words.apply(
MapElements.into(TypeDescriptors.integers())
.via((String word) -> word.length()));
public <NewInputT> MapElements<NewInputT,OutputT> via(SerializableFunction<NewInputT,OutputT> fn)
via(ProcessFunction)
.public <NewInputT> MapElements<NewInputT,OutputT> via(Contextful<Contextful.Fn<NewInputT,OutputT>> fn)
via(ProcessFunction)
, but supports access to context, such as side inputs.public PCollection<OutputT> expand(PCollection<? extends InputT> input)
PTransform
PTransform
should be expanded on the given
InputT
.
NOTE: This method should not be called directly. Instead apply the PTransform
should
be applied to the InputT
using the apply
method.
Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).
expand
in class PTransform<PCollection<? extends InputT>,PCollection<OutputT>>
public void populateDisplayData(DisplayData.Builder builder)
PTransform
populateDisplayData(DisplayData.Builder)
is invoked by Pipeline runners to collect
display data via DisplayData.from(HasDisplayData)
. Implementations may call super.populateDisplayData(builder)
in order to register display data in the current namespace,
but should otherwise use subcomponent.populateDisplayData(builder)
to use the namespace
of the subcomponent.
By default, does not register any display data. Implementors may override this method to provide their own display data.
populateDisplayData
in interface HasDisplayData
populateDisplayData
in class PTransform<PCollection<? extends InputT>,PCollection<OutputT>>
builder
- The builder to populate with display data.HasDisplayData
public <NewFailureT> MapElements.MapWithFailures<InputT,OutputT,NewFailureT> exceptionsInto(TypeDescriptor<NewFailureT> failureTypeDescriptor)
MapElements.MapWithFailures
transform that catches exceptions raised while mapping
elements, with the given type descriptor used for the failure collection but the exception
handler yet to be specified using MapElements.MapWithFailures.exceptionsVia(ProcessFunction)
.
See WithFailures
documentation for usage patterns of the returned WithFailures.Result
.
public <FailureT> MapElements.MapWithFailures<InputT,OutputT,FailureT> exceptionsVia(InferableFunction<WithFailures.ExceptionElement<InputT>,FailureT> exceptionHandler)
MapElements.MapWithFailures
transform that catches exceptions raised while mapping
elements, passing the raised exception instance and the input element being processed through
the given exceptionHandler
and emitting the result to a failure collection.
This method takes advantage of the type information provided by InferableFunction
,
meaning that a call to exceptionsInto(TypeDescriptor)
may not be necessary.
See WithFailures
documentation for usage patterns of the returned WithFailures.Result
.
Example usage:
Result<PCollection<String>, String>> result = words.apply(
MapElements
.into(TypeDescriptors.integers())
.via((String word) -> 1 / word.length) // Could throw ArithmeticException
.exceptionsVia(new WithFailures.ExceptionAsMapHandler<String>() {}));
PCollection<Integer> output = result.output();
PCollection<String> failures = result.failures();