Class RowTargetBase<TDerived, TInput>

An abstract dataflow worker which repeatedly executes the OnInputRow(TInput) method when there is an input row available on the Input port. The library user must inherit this class and override OnInputRow to provide custom functionality.

OnInputRow(TInput) is passed the row as a parameter, and does not itself take rows from the input port. If the method throws an exception, the worker will receive a Fatal status.

This class simplifies the implementation by allowing the developer to write synchronous code that operates on a single row at a time, without having to check for the availability of incoming rows.

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.

Use RowWithErrorTargetBase<TDerived, TInputError> if an error output port is needed. Also see the RowTargetBase example.

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

Inheritance
Object
WorkerParent
WorkerBase
WorkerBase<TDerived>
RowsTargetBase<TDerived, TInput>
RowTargetBase<TDerived, TInput>
RowActionTarget<TInput>
Implements
Inherited Members
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public abstract class RowTargetBase<TDerived, TInput> : RowsTargetBase<TDerived, TInput>, IDisposeOnFinished where TDerived : RowTargetBase<TDerived, TInput> where TInput : class
Type Parameters
Name Description
TDerived

The type of the derived worker. Class definition example:

public class MyTarget<TInput>
    : RowTargetBase<MyTarget<TInput>,TInput>
    where TInput : class
{ 
    // ...
}
TInput

The type of each Input row.

Constructors

RowTargetBase(in DownstreamFactory<TInput>, String)

Initializes a new instance of the RowTargetBase<TDerived, TInput> abstract dataflow worker, which repeatedly executes the OnInputRow method when there are input rows available on the Input port.

Declaration
protected RowTargetBase(in DownstreamFactory<TInput> downstreamFactory, string workerName)
Parameters
Type Name Description
DownstreamFactory<TInput> 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 "__".

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?

Methods

OnInputRow(TInput)

An abstract method that gets called repeatedly when there is an input row available on the Input port. Override it and process each incoming row.

Declaration
protected abstract ProgressStatus OnInputRow(TInput inputRow)
Parameters
Type Name Description
TInput inputRow

The incoming row. Guaranteed to not be null.
Returns
Type Description
ProgressStatus
  • NotCompleted to continue to be called when there are input rows available.
  • Succeeded to discard all additional incoming rows, and successfully finish row processing and the worker.
  • Error or Fatal to fail the worker.

OnInputRowsAsync()

For internal use.

Declaration
protected sealed override Task<ProgressStatus> OnInputRowsAsync()
Returns
Type Description
Task<ProgressStatus>
Overrides
actionETL.RowsTargetBase<TDerived, TInput>.OnInputRowsAsync()

Implements

See Also

RowWithErrorTargetBase<TDerived, TInputError>