Fix NTS geometries stored as invalid geographies in SQL Server

[Copilot]

SqlServerBytesWriter v2.1.0 sets the IsValid flag in the SQL Server binary format (MS-SSCLRT) based on NTS's Geometry.IsValid. NTS and SQL Server use different validation rules, so geometries NTS considers invalid (e.g., minor ring self-intersections common in real-world GIS data) get the V flag set to false. SQL Server's STIsValid() reads this flag from the binary without re-validating, returning 0.

• GeometryValueConverter: Post-process the serialized bytes from SqlServerBytesWriter to always set the IsValid flag (bit 2 of the Properties byte at offset 5) to true, decoupling NTS validation from SQL Server's validity flag

// Before: NTS IsValid propagated to SQL Server V flag
g => new SqlBytes(writer.Write(g))

// After: V flag always set to true
g => new SqlBytes(SetIsValidFlag(writer.Write(g)))

• Unit tests: Added tests covering valid/invalid geometries and geographies, verifying the flag is always set and roundtrip data is preserved

Original prompt

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This section details on the original issue you should resolve

<issue_title>Some NTS Geometry objects endup as invalid Geographies in Sql Server</issue_title>
<issue_description>### Bug description

Context

• Windows 11
• SQL Server 2017
• EF Core 8.0.18 (I also tried on .NET 10 and EF Core 10.0.1, and same issue)

Problem
I build a NTS Geometry object and assign it to an object's field, which is then persisted to a table using EF Core.

The record is stored in the database properly, but when I do:

SELECT Geography.STIsValid() FROM MyTable

It returns 0

The issue only happens with certain shapes (the attached one is an example)

geo.txt

Your code

class MyTable
        {
            public int Id { get; set; }

            public Geometry? Geography { get; set; }
        }

        class MyDBContext : DbContext
        {
            public DbSet<MyTable> MyTable { get; set; }

            public MyDBContext(DbContextOptions<MyDBContext> options) : base(options)
            {
            }
        }

        [Test]
        public void TestDodgyGeography()
        {
            var options = new DbContextOptionsBuilder<MyDBContext>()
                .UseSqlServer("Data Source=localhost;Initial Catalog=MyDB;User ID=sa;Password=Pass1234;Trust Server Certificate=true", x => x.UseNetTopologySuite())
                .Options;
            var context = new MyDBContext(options);
            var geo = new WKTReader(new NtsGeometryServices(PrecisionModel.Floating.Value, 4269)).Read("MY MULTIPOLYGON IS TOO BIG SO I HAVE ADDED IT AS AN ATTACHMENT");
            context.MyTable.Add(new MyTable { Id = 1, Geography = geo });
            context.SaveChanges();
        }

Stack traces

Verbose output

EF Core version

8.0.18

Database provider

Microsoft.EntityFrameworkCore.SqlServer

Target framework

.NET 8

Operating system

Windows 11

IDE

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Some NTS Geometry objects endup as invalid Geographies in Sql Server #37416

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