Fix identity column handling for generated GUIDs on SQL server and add corresponding tests (#54)

Author: PhenX

src/PhenX.EntityFrameworkCore.BulkInsert.SqlServer/SqlServerDialectBuilder.cs

@@ -34,7 +34,8 @@ public override string BuildMoveDataSql<T>(
     {
         var q = new StringBuilder();
 
-        if (options.CopyGeneratedColumns)
+        var identityInsert = options.CopyGeneratedColumns && insertedColumns.Any(x => x.IsGenerated);
+        if (identityInsert)
         {
             q.AppendLine($"SET IDENTITY_INSERT {target.QuotedTableName} ON;");
         }
@@ -129,7 +130,7 @@ public override string BuildMoveDataSql<T>(
 
         q.AppendLine(";");
 
-        if (options.CopyGeneratedColumns)
+        if (identityInsert)
         {
             q.AppendLine($"SET IDENTITY_INSERT {target.QuotedTableName} OFF;");
         }

src/PhenX.EntityFrameworkCore.BulkInsert/Metadata/ColumnMetadata.cs

@@ -22,7 +22,7 @@ internal sealed class ColumnMetadata(IProperty property,  SqlDialectBuilder dial
 
     public Type ClrType { get; } = property.ClrType;
 
-    public bool IsGenerated { get; } = property.ValueGenerated == ValueGenerated.OnAdd;
+    public bool IsGenerated { get; } = property.ValueGenerated != ValueGenerated.Never;
 
     public object? GetValue(object entity, BulkInsertOptions options)
     {

tests/PhenX.EntityFrameworkCore.BulkInsert.Tests/DbContext/TestEntityWithGeneratedGuidId.cs

@@ -261,4 +261,26 @@ await _context.ExecuteBulkInsertAsync(entities, (SqlServerBulkInsertOptions _) =
                 }));
         }
     }
+
+    [SkippableTheory]
+    [CombinatorialData]
+    public async Task InsertEntities_WithGeneratedGuidId(InsertStrategy strategy)
+    {
+        // Arrange
+        var entities = new List<TestEntityWithGuidId>
+        {
+            new TestEntityWithGuidId { Id = Guid.NewGuid(), Name = $"{_run}_Entity1" },
+            new TestEntityWithGuidId { Id = Guid.NewGuid(), Name = $"{_run}_Entity2" }
+        };
+
+        // Act
+        var insertedEntities = await _context.InsertWithStrategyAsync(strategy, entities, configure => configure.CopyGeneratedColumns = true);
+
+        // Assert
+        insertedEntities.Should().BeEquivalentTo(entities,
+            o=> o
+                .RespectingRuntimeTypes()
+                .Excluding(e => e.Id)
+            );
+    }
 }