Walkthrough - Implement DateOnly/TimeOnly Support

I have implemented support for generating System.DateOnly and System.TimeOnly types for xs:date and xs:time XML schema types.

Changes

1. GeneratorConfiguration.cs and Generator.cs

Added a new configuration property UseDateOnly.

// GeneratorConfiguration.cs
public bool UseDateOnly { get; set; } = false;

// Generator.cs
public bool UseDateOnly
{
    get { return _configuration.UseDateOnly; }
    set { _configuration.UseDateOnly = value; }
}

2. CodeUtilities.cs

• Added internal DateOnly and TimeOnly structs to allow the generator to identify these types even when running on older .NET frameworks (netstandard2.0).
• Updated GetEffectiveType to map XmlTypeCode.Date and XmlTypeCode.Time to these internal types when UseDateOnly is true.
• Updated CreateTypeReference to map the internal types to System.DateOnly and System.TimeOnly string references in the generated code.

3. TypeModel.cs

Updated GetDefaultValueFor to handle standard default value parsers for DateOnly and TimeOnly (using .Parse()).

4. Program.cs

Added a new command line option --dateOnly (or -do) to the CLI.

xscgen -do schema.xsd

Verification

I added a new test file XmlSchemaClassGenerator.Tests/DateOnlyTimeOnlyTests.cs and confirmed that:

• When -do is enabled, xs:date generates public System.DateOnly PropertyName.
• When -do is enabled, xs:time generates public System.TimeOnly PropertyName.
• When disabled, it falls back to DateTime.
• Verified that default values for xs:date and xs:time are correctly parsed using System.DateOnly.Parse and System.TimeOnly.Parse.
• Verified that xs:time and xs:date correctly map to DateTimeOffset when UseDateOnly is false and DateTimeWithTimeZone is true.

Usage

To use the new feature via CLI:

xscgen -do input.xsd

To use via code:

var generator = new Generator
{
    UseDateOnly = true
};
generator.Generate(schemaSet);

(implemented by Gemini Pro 3)

This should fix #524 and #310