Class FixedWidthTransformer<TSource, TDestination>

Namespace: Wolfgang.Etl.FixedWidth

Assembly: Wolfgang.Etl.FixedWidth.dll

Transforms a stream of TSource records into TDestination records in a single streaming pass (#14) — the middle stage of an extract → transform → load pipeline. Compose it between a FixedWidthExtractor<TRecord> reading one fixed-width layout and a FixedWidthLoader<TRecord> writing another to reformat a file (reorder, add/remove, or reformat fields).

public sealed class FixedWidthTransformer<TSource, TDestination> : TransformerBase<TSource, TDestination, FixedWidthReport>, ITransformWithProgressAndCancellationAsync<TSource, TDestination, FixedWidthReport>, ITransformWithCancellationAsync<TSource, TDestination>, ITransformWithProgressAsync<TSource, TDestination, FixedWidthReport>, ITransformAsync<TSource, TDestination>, IReportsItemErrors, IAsyncDisposable, IDisposable where TSource : notnull where TDestination : notnull

Type Parameters

TSource: The source record type.
TDestination: The destination record type.

Inheritance: object

TransformerBase<TSource, TDestination, FixedWidthReport>

FixedWidthTransformer<TSource, TDestination>

Implements: ITransformWithProgressAndCancellationAsync<TSource, TDestination, FixedWidthReport>

ITransformWithCancellationAsync<TSource, TDestination>

ITransformWithProgressAsync<TSource, TDestination, FixedWidthReport>

ITransformAsync<TSource, TDestination>

IReportsItemErrors

IAsyncDisposable

IDisposable

Inherited Members: TransformerBase<TSource, TDestination, FixedWidthReport>.TransformAsync(IAsyncEnumerable<TSource>)

TransformerBase<TSource, TDestination, FixedWidthReport>.TransformAsync(IAsyncEnumerable<TSource>, CancellationToken)

TransformerBase<TSource, TDestination, FixedWidthReport>.TransformAsync(IAsyncEnumerable<TSource>, IProgress<FixedWidthReport>)

TransformerBase<TSource, TDestination, FixedWidthReport>.TransformAsync(IAsyncEnumerable<TSource>, IProgress<FixedWidthReport>, CancellationToken)

TransformerBase<TSource, TDestination, FixedWidthReport>.DisposeAsync()

TransformerBase<TSource, TDestination, FixedWidthReport>.Dispose()

TransformerBase<TSource, TDestination, FixedWidthReport>.ReportingInterval

TransformerBase<TSource, TDestination, FixedWidthReport>.CurrentItemCount

TransformerBase<TSource, TDestination, FixedWidthReport>.CurrentSkippedItemCount

TransformerBase<TSource, TDestination, FixedWidthReport>.CurrentErrorItemCount

TransformerBase<TSource, TDestination, FixedWidthReport>.MaximumItemCount

TransformerBase<TSource, TDestination, FixedWidthReport>.SkipItemCount

TransformerBase<TSource, TDestination, FixedWidthReport>.WorkerResilience

TransformerBase<TSource, TDestination, FixedWidthReport>.ErrorPolicy

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Examples

using var extractor = new FixedWidthExtractor<LegacyRecord>(sourceReader);
using var transformer = new FixedWidthTransformer<LegacyRecord, ModernRecord>(
    legacy => new ModernRecord { Id = legacy.OldId, Name = legacy.FullName });
using var loader = new FixedWidthLoader<ModernRecord>(destinationWriter);

var modern = transformer.TransformAsync(extractor.ExtractAsync(token), token);
await loader.LoadAsync(modern, token);

Constructors

FixedWidthTransformer(Func<TSource, TDestination>, ILogger<FixedWidthTransformer<TSource, TDestination>>?)

Creates a transformer that projects each source record with transform. The projection handles every reformatting case — reordered, added, removed, or format-converted fields.

public FixedWidthTransformer(Func<TSource, TDestination> transform, ILogger<FixedWidthTransformer<TSource, TDestination>>? logger = null)

Parameters

transform Func<TSource, TDestination>: The per-record projection.
logger ILogger<FixedWidthTransformer<TSource, TDestination>>: An optional ILogger<TCategoryName> for diagnostic output. When null — or omitted — Instance is used and logging is disabled.

Exceptions

ArgumentNullException: transform is null.

FixedWidthTransformer(Func<TSource, TDestination>, FixedWidthTransformerOptions?, ILogger<FixedWidthTransformer<TSource, TDestination>>?)

Initializes a new FixedWidthTransformer<TSource, TDestination> with the base-stage configuration taken from options (ADR-0009).

public FixedWidthTransformer(Func<TSource, TDestination> transform, FixedWidthTransformerOptions? options, ILogger<FixedWidthTransformer<TSource, TDestination>>? logger = null)

Parameters

transform Func<TSource, TDestination>: The per-record transformation.
options FixedWidthTransformerOptions: The stage configuration (ReportingInterval, MaximumItemCount, SkipItemCount, ErrorPolicy); null keeps the defaults.
logger ILogger<FixedWidthTransformer<TSource, TDestination>>: The logger; null logs nothing.

Exceptions

ArgumentNullException: transform is null.

Methods

ByMatchingProperties()

Creates a transformer that copies every source property to the destination property of the same name and an assignable type. TDestination must have a public parameterless constructor. Use the projection constructor for anything beyond a straight same-name copy (reordering, format conversion, combining fields).

public static FixedWidthTransformer<TSource, TDestination> ByMatchingProperties()

Returns

FixedWidthTransformer<TSource, TDestination>

CreateProgressReport()

Creates a progress report object of type TProgress.

protected override FixedWidthReport CreateProgressReport()

Returns

FixedWidthReport: TProgress - A new instance of the progress report object.

CreateProgressTimer(IProgress<FixedWidthReport>)

Creates the Wolfgang.Etl.Abstractions.IProgressTimer used to drive progress callbacks. Override this method in a derived class to inject a custom timer (for example, a custom implementation that allows manual control in unit tests).

protected override IProgressTimer CreateProgressTimer(IProgress<FixedWidthReport> progress)

Parameters

progress IProgress<FixedWidthReport>: The progress sink that will receive callbacks.

Returns

IProgressTimer: A started Wolfgang.Etl.Abstractions.IProgressTimer instance.

TransformWorkerAsync(IAsyncEnumerable<TSource>, CancellationToken)

The worker method that performs the actual transformation.

protected override IAsyncEnumerable<TDestination> TransformWorkerAsync(IAsyncEnumerable<TSource> source, CancellationToken cancellationToken)

Parameters

source IAsyncEnumerable<TSource>
cancellationToken CancellationToken

Returns

IAsyncEnumerable<TDestination>: IAsyncEnumerable<TDestination> - The result may be an empty sequence if no data is available or if the transformation fails.