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GerstITS.Examples.Transactions/Migrations/SqliteInMemoryDatabaseConfigurator.cs

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+using GerstITS.Data.EntityFramework;
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+
+namespace GerstITS.Examples.Transactions.Migrations;
+
+/// <summary>
+/// Configures <see cref="ProductDbContext" /> to use a self-contained SQLite in-memory database.
+///
+/// SQLite is a RELATIONAL provider and therefore supports real ACID transactions, which is what the
+/// transaction example needs to show an atomic rollback that actually discards partial work.
+///
+/// The EF Core InMemory provider (<c>UseInMemoryDatabase</c>) is deliberately NOT used here: it does
+/// not support transactions at all - <c>Database.BeginTransaction()</c> raises the
+/// <c>TransactionIgnoredWarning</c> - so it cannot demonstrate an atomic rollback. In production the
+/// same code runs unchanged against PostgreSQL or SQL Server.
+///
+/// A single <see cref="SqliteConnection" /> is opened and kept open for the lifetime of the process so
+/// the in-memory database is shared across every <see cref="ProductDbContext" /> instance (an in-memory
+/// SQLite database only lives as long as its connection is open).
+/// </summary>
+public sealed class SqliteInMemoryDatabaseConfigurator : DatabaseConfiguratorBase, IDisposable
+{
+    #region Fields
+
+    private readonly SqliteConnection _connection;
+
+    #endregion
+
+    #region Constructors
+
+    public SqliteInMemoryDatabaseConfigurator(IConfiguration configuration)
+        : base(configuration)
+    {
+        _connection = new SqliteConnection("DataSource=:memory:");
+        _connection.Open();
+    }
+
+    #endregion
+
+    #region DatabaseConfiguratorBase
+
+    public override void ConfigureModelCreating(ModelBuilder modelBuilder)
+    {
+        // No relational-specific mapping is required; ProductEntity is mapped by convention.
+    }
+
+    protected override void ConfigureDatabase(DbContextOptionsBuilder optionsBuilder, string connectionString)
+    {
+        optionsBuilder.UseSqlite(_connection);
+    }
+
+    #endregion
+
+    #region IDisposable
+
+    public void Dispose()
+    {
+        _connection.Dispose();
+    }
+
+    #endregion
+}