Support byte[] BSON binary and add tests

src/BLite.SourceGenerators/CodeGenerator.cs

@@ -333,7 +333,7 @@ private static void GenerateWriteProperty(StringBuilder sb, PropertyInfo prop, s
                     var writeMethod = GetPrimitiveWriteMethod(prop, allowKey: false);
                     if (writeMethod != null)
                     {
-                        if (prop.IsNullable || prop.TypeName == "string" || prop.TypeName == "String")
+                        if (prop.IsNullable || prop.TypeName == "string" || prop.TypeName == "String" || prop.TypeName == "byte[]")
                         {
                             sb.AppendLine($"            if (entity.{prop.Name} != null)");
                             sb.AppendLine($"            {{");
@@ -718,6 +718,27 @@ private static void GenerateReadPropertyToLocal(StringBuilder sb, PropertyInfo p
                  var readMethod = GetPrimitiveReadMethod(prop);
                  if (readMethod != null)
                  {
+                    if (readMethod == "ReadBinary")
+                    {
+                        // ReadBinary returns ReadOnlySpan<byte> — must call .ToArray() to materialise
+                        if (prop.IsNullable)
+                        {
+                            sb.AppendLine($"                        if ({bsonTypeVar} == global::BLite.Bson.BsonType.Null)");
+                            sb.AppendLine($"                        {{");
+                            sb.AppendLine($"                            {localVar} = null;");
+                            sb.AppendLine($"                        }}");
+                            sb.AppendLine($"                        else");
+                            sb.AppendLine($"                        {{");
+                            sb.AppendLine($"                            {localVar} = reader.ReadBinary(out _).ToArray();");
+                            sb.AppendLine($"                        }}");
+                        }
+                        else
+                        {
+                            sb.AppendLine($"                        {localVar} = reader.ReadBinary(out _).ToArray();");
+                        }
+                    }
+                    else
+                    {
                     var cast = (prop.TypeName == "float" || prop.TypeName == "Single") ? "(float)" : "";
 
                     // Handle nullable types - check for null in BSON stream
@@ -738,6 +759,7 @@ private static void GenerateReadPropertyToLocal(StringBuilder sb, PropertyInfo p
                         var readArgs = IsCoercedReadMethod(readMethod) ? $"({bsonTypeVar})" : "()";
                         sb.AppendLine($"                        {localVar} = {cast}reader.{readMethod}{readArgs};");
                     }
+                    }
                  }
                  else if (prop.ConverterTypeName != null)
                  {
@@ -931,6 +953,7 @@ private static string GetBaseMapperClass(PropertyInfo? keyProp, EntityInfo entit
             if (cleanType.EndsWith("TimeOnly")) return "WriteTimeOnly";
             if (cleanType.EndsWith("Guid")) return "WriteGuid";
             if (cleanType.EndsWith("ObjectId")) return "WriteObjectId";
+            if (cleanType == "byte[]") return "WriteBinary";
 
             return null;
         }
@@ -964,6 +987,7 @@ private static string GetBaseMapperClass(PropertyInfo? keyProp, EntityInfo entit
             if (cleanType.EndsWith("TimeOnly")) return "ReadTimeOnly";
             if (cleanType.EndsWith("Guid")) return "ReadGuid";
             if (cleanType.EndsWith("ObjectId")) return "ReadObjectId";
+            if (cleanType == "byte[]") return "ReadBinary";
 
             return null;
         }
@@ -1025,6 +1049,7 @@ private static string QualifyType(string typeName)
                 case "object":
                 case "dynamic":
                 case "void":
+                case "byte[]":
                     return baseType + (isNullable ? "?" : "");
                 case "Guid": return "global::System.Guid" + (isNullable ? "?" : "");
                 case "DateTime": return "global::System.DateTime" + (isNullable ? "?" : "");

src/BLite.SourceGenerators/Helpers/SyntaxHelper.cs

@@ -143,6 +143,9 @@ public static bool IsCollectionType(ITypeSymbol type, out ITypeSymbol? itemType)
             // Handle arrays
             if (type is IArrayTypeSymbol arrayType)
             {
+                // Exclude byte[] — it maps to BSON Binary, not a sequence of integers
+                if (arrayType.ElementType.SpecialType == SpecialType.System_Byte)
+                    return false;
                 itemType = arrayType.ElementType;
                 return true;
             }

tests/BLite.Shared/MockEntities.cs

@@ -199,6 +199,16 @@ public class DddLineItem
         public int Quantity { get; set; }
     }
 
+    // --- Binary Property Tests ---
+
+    public class BinaryEntity
+    {
+        public ObjectId Id { get; set; }
+        public string Label { get; set; } = "";
+        public byte[] Data { get; set; } = Array.Empty<byte>();
+        public byte[]? OptionalData { get; set; }
+    }
+
     public record OrderId(string Value)
     {
         public OrderId() : this(string.Empty) { }

tests/BLite.Shared/TestDbContext.cs

@@ -80,6 +80,9 @@ public partial class TestDbContext : DocumentDbContext
     // Device – HasConversion on a non-ID property (ulong → long)
     public DocumentCollection<string, Device> Devices { get; set; } = null!;
 
+    // Binary Property Tests
+    public DocumentCollection<ObjectId, BinaryEntity> BinaryEntities { get; set; } = null!;
+
     public TestDbContext(string databasePath) : base(databasePath)
     {
         InitializeCollections();
@@ -183,6 +186,9 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 
         // Benchmark entities
         modelBuilder.Entity<CustomerOrder>().ToCollection("customer_orders").HasKey(e => e.Id);
+
+        // Binary Property Tests
+        modelBuilder.Entity<BinaryEntity>().ToCollection("binary_entities");
     }
 
     public void ForceCheckpoint()