Class FixedWidthConverter

Namespace: Wolfgang.Etl.FixedWidth

Assembly: Wolfgang.Etl.FixedWidth.dll

Provides built-in value converter, header converter, and value parser functions for use with FixedWidthLoader<TRecord, TProgress> and FixedWidthExtractor<TRecord, TProgress>.

public static class FixedWidthConverter

Inheritance: object

FixedWidthConverter

Inherited Members: object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

Value converters (Func<T1, T2, TResult> of object, FieldContext, string) convert a typed property value to its string representation. Rules:

DateTime, DateTimeOffset, and TimeSpan require an explicit Format. An InvalidOperationException is thrown if none is provided.
All other IFormattable types use InvariantCulture with the optional Format if supplied.
Null values are converted to Empty.

Header converters (Func<T1, T2, TResult> of string, FieldContext, string) convert a header label to its padded string representation.

Value parsers (Func<T1, T2, TResult> of string, FieldContext, object) convert a raw string read from the file back to the target property type. DefaultParser is the built-in implementation used by FixedWidthExtractor<TRecord, TProgress> by default.

Fields

DefaultParser

Converts a raw string read from the file to the target property type indicated by PropertyType. This is the default ValueParser.

public static readonly FixedWidthValueParser DefaultParser

Field Value

FixedWidthValueParser

Examples

// Use DefaultParser explicitly (it is also the default):
extractor.ValueParser = FixedWidthConverter.DefaultParser;

// Handle "Y"/"N" booleans, fall back to DefaultParser for everything else:
extractor.ValueParser = (text, ctx) =>
    ctx.PropertyType == typeof(bool)
        ? (object)(text.Span.SequenceEqual("Y".AsSpan()))
        : FixedWidthConverter.DefaultParser(text, ctx);

Remarks

Nullable types: empty string returns null, non-empty recurses on the underlying type.
string: returned as-is.
Empty string for non-nullable value types: returns the default value (e.g. 0 for int).
DateTime, DateTimeOffset, TimeSpan: parsed with Format using InvariantCulture.
All other types: parsed via TypeDescriptor with InvariantCulture.

Exceptions

InvalidOperationException: Thrown when parsing a DateTime, DateTimeOffset, or TimeSpan value and no Format has been specified on the field attribute.
FormatException: Thrown when the raw string value cannot be parsed into the target type because the value does not match the expected format.

Strict

Converts the value to a string and throws a FieldOverflowException if the result exceeds FieldLength. This is the default value converter used by FixedWidthLoader<TRecord, TProgress>.

public static readonly Func<object, FieldContext, string> Strict

Field Value

Func<object, FieldContext, string>

Examples

// Use Strict explicitly (it is also the default):
loader.ValueConverter = FixedWidthConverter.Strict;

// Fall back to Strict for all types except bool:
loader.ValueConverter = (value, ctx) =>
    ctx.PropertyType == typeof(bool)
        ? ((bool)value ? "Y" : "N")
        : FixedWidthConverter.Strict(value, ctx);

Exceptions

FieldOverflowException: Thrown when the converted string is longer than FieldLength.
InvalidOperationException: Thrown when converting a DateTime, DateTimeOffset, or TimeSpan value and no Format has been specified on the field attribute.

StrictHeader

Validates that the header label fits within FieldLength, throwing a FieldOverflowException if it does not, then returns the label unchanged. Space-padding is applied by the framework after the converter returns. This is the default header converter used by FixedWidthLoader<TRecord, TProgress>.

public static readonly Func<string, FieldContext, string> StrictHeader

Field Value

Func<string, FieldContext, string>

Examples

// Use StrictHeader explicitly (it is also the default):
loader.HeaderConverter = FixedWidthConverter.StrictHeader;

// Convert header labels to upper-case, still enforcing the field width:
loader.HeaderConverter = (label, ctx) =>
    FixedWidthConverter.StrictHeader(label.ToUpperInvariant(), ctx);

Remarks

The FieldContext is passed as-is from the attribute. If you want different alignment or padding for header cells, supply a custom HeaderConverter.

Exceptions

FieldOverflowException: Thrown when the header label is longer than FieldLength.

Truncate

Converts the value to a string and silently truncates it to FieldLength if it is too long.

public static readonly Func<object, FieldContext, string> Truncate

Field Value

Func<object, FieldContext, string>

Examples

// Use Truncate when long values should be silently clipped:
loader.ValueConverter = FixedWidthConverter.Truncate;

Exceptions

InvalidOperationException: Thrown when converting a DateTime, DateTimeOffset, or TimeSpan value and no Format has been specified on the field attribute.

TruncateHeader

Silently truncates the header label to FieldLength if it is too long, then returns it unchanged otherwise. Space-padding is applied by the framework after the converter returns.

public static readonly Func<string, FieldContext, string> TruncateHeader

Field Value

Func<string, FieldContext, string>

Examples

// Use TruncateHeader when header labels may exceed the field width:
loader.HeaderConverter = FixedWidthConverter.TruncateHeader;