DKNet

Format resolved values

Part of DKNet.Svc.Transformation. The default ValueFormatter turns a resolved value into its display string before it replaces the token in the template.

using DKNet.Svc.Transformation;
using DKNet.Svc.Transformation.Convertors;
using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddTransformerService(options => options.Formatter = new IsoDateFormatter());

public sealed class IsoDateFormatter : ValueFormatter
{
    public override string DateFormat { get; set; } = "yyyy-MM-dd";
}

Convert receives the IToken as well as the value, so a custom formatter can branch on token.Key when one template needs a token-specific format.

This does not show what happens before formatting — token extraction and resolution — or the not-found policy (see fill a template from data). Under ThrowError an unresolved token never reaches Convert; under LeaveAsIs and Remove the substitute text (the raw token or an empty string) still passes through Convert.

public virtual string DateFormat { get; set; } = "dd/MM/yyyy hh.mm.ss";
public virtual string IntegerFormat { get; set; } = "###,##0";
public virtual string NumberFormat { get; set; } = "###,##0.00";

bool becomes "Yes"/"No"; int/long use IntegerFormat; double/decimal/float use NumberFormat; DateTime/DateTimeOffset use DateFormat; everything else falls back to ToString(). All numeric and date formatting runs against CultureInfo.InvariantCulture, so output does not shift with the thread’s culture.

⚙️ Configuration reference

Option	Type	Default	Effect
Formatter	IValueFormatter	new ValueFormatter()	Converts each resolved value to its display string.
ValueFormatter.DateFormat	string	"dd/MM/yyyy hh.mm.ss"	Format string for DateTime/DateTimeOffset values.
ValueFormatter.IntegerFormat	string	"###,##0"	Format string for int/long values.
ValueFormatter.NumberFormat	string	"###,##0.00"	Format string for double/decimal/float values.

⚠️ Gotchas & limits

• The default date format is 12-hour with no meridiem. "dd/MM/yyyy hh.mm.ss" renders 13:05 as 01.05.00 — override DateFormat (e.g. "HH:mm") for anything a reader must interpret unambiguously.
• IValueFormatter/ValueFormatter are the one fully open extension point here. Subclass ValueFormatter to change just the formats, or implement IValueFormatter directly for full control (a non-numeric, non-date, non-bool type, or a type-specific format), then assign TransformOptions.Formatter.

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