Class RowTransformBase<TDerived, TInputError, TOutput>

An abstract dataflow worker with and Input, Output, and ErrorOutput port, where Input and ErrorOutput have the same type, which repeatedly executes the OnInputRow(TInputError) method on each incoming row. The method returns a (usually different) output row to the downstream worker, or no row at all. When outputting a row, the function is responsible for either allocating a new output row, or if appropriate cast the input row to the output type, before passing returning it.

The library user must inherit this class and override OnInputRow to provide custom functionality.

If the method throws an exception, the input row will be rejected to the ErrorOutput port.

The derived class can additionally override RunAsync() to add logic that runs before and after all processing of rows, in which case the base class base.RunAsync() must be called. The derived class (or its user) can also use worker callbacks to add logic.

The input port uses the Default policy. Consider whether this is appropriate, or should be overridden, see BufferingMode for further details.

Use RowTransformBase<TDerived, TInputOutputError> instead if the all ports have the same row type. Also see the RowTransformBase example.

Inheritance
Object
WorkerParent
WorkerBase
WorkerBase<TDerived>
RowsTransformBase<TDerived, TInputError, TOutput>
RowTransformBase<TDerived, TInputError, TOutput>
RowActionTransform<TInputError, TOutput>
Implements
Inherited Members
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public abstract class RowTransformBase<TDerived, TInputError, TOutput> : RowsTransformBase<TDerived, TInputError, TOutput>, IDisposeOnFinished where TDerived : RowTransformBase<TDerived, TInputError, TOutput> where TInputError : class where TOutput : class
Type Parameters
Name Description
TDerived

The type of the derived worker. Class definition example:

public class MyTransform<TInputError,TOutput>
    : RowTransformBase<MyTransform<TInputError,TOutput>,TInputError,TOutput>
    where TInputError : class
    where TOutput : class
{ 
    // ...
}
TInputError

The type of each Input and ErrorOutput row.
TOutput

The type of each Output row.

Constructors

RowTransformBase(in DownstreamFactory<TInputError>, String, Boolean)

Initializes a new instance of the RowTransformBase<TDerived, TInputOutputError> abstract dataflow worker, which repeatedly executes the OnInputRow method when there are input rows and output demand available on the ports.

Declaration
protected RowTransformBase(in DownstreamFactory<TInputError> downstreamFactory, string workerName, bool autoCompleteOutput)
Parameters
Type Name Description
DownstreamFactory<TInputError> downstreamFactory

The downstream factory, which specifies the parent worker and (optionally) the upstream port to link the "first" input port of this dataflow worker to.

Get it from Link when the upstream port is known ahead of time (which is usually the case). Otherwise get it from GetDownstreamFactory<TInput>(), and link the transform or target explicitly using LinkTo(InputPort<TOutput>) or LinkFrom(OutputPortBase<TInput>).

String workerName

Name of the worker.

Set to a prefix plus a trailing "/" (e.g. "MyPrefix-/") to generate a unique name from the prefix plus an increasing number starting at 1.

While less useful, set to null, whitespace or "/" to generate a unique name from the worker type plus an increasing number starting at 1.

The name cannot otherwise contain "/", and cannot start with double underscore "__".

Boolean autoCompleteOutput

After the final call to OnRowsAndDemandAsync():

Exceptions
Type Condition
ArgumentException

workerName:

  • Workers with the same parent must have unique names.
  • Worker and worker system names cannot contain '/' or start with double underscore '__'.
ArgumentNullException

workerParent - All workers must have a parent. The top level workers have the worker system as parent.
InvalidOperationException
  • Cannot add child worker to parent which has completed. Are you adding it to the correct parent?
  • Cannot add worker to parent, since its children have been started. Are you adding it to the correct parent?

Properties

ErrorOutput

Gets the error output port for sending error rows to logging and an optional downstream worker.

Declaration
public ErrorOutputPort<TInputError> ErrorOutput { get; }
Property Value
Type Description
ErrorOutputPort<TInputError>

Methods

OnInputRow(TInputError)

An abstract synchronous method that will get called for each incoming row. Override it and process each incoming row.

Declaration
protected abstract (TransformRowTreatment, TOutput) OnInputRow(TInputError inputRow)
Parameters
Type Name Description
TInputError inputRow

The incoming row. Guaranteed to not be null.
Returns
Type Description
(T1, T2)<TransformRowTreatment, TOutput>

If and how the input row should be passed to downstream workers.

OnRowsAndDemandAsync()

For internal use.

Declaration
protected sealed override Task<ProgressStatus> OnRowsAndDemandAsync()
Returns
Type Description
Task<ProgressStatus>
Overrides
actionETL.RowsTransformBase<TDerived, TInputError, TOutput>.OnRowsAndDemandAsync()

Implements

See Also

RowTransformBase<TDerived, TInputOutputError>