diff --git a/src/Luban.Job.Common/Source/Types/TMap.cs b/src/Luban.Job.Common/Source/Types/TMap.cs
index 9753ba7..d7a5917 100644
--- a/src/Luban.Job.Common/Source/Types/TMap.cs
+++ b/src/Luban.Job.Common/Source/Types/TMap.cs
@@ -5,6 +5,8 @@ namespace Luban.Job.Common.Types
 {
     public class TMap : TType
     {
+        public bool IsMap => true;
+
         public TType KeyType { get; }
 
         public TType ValueType { get; }
diff --git a/src/Luban.Job.Db/Source/Defs/TTypeTemplateExtends.cs b/src/Luban.Job.Db/Source/Defs/TTypeTemplateExtends.cs
index e6150cf..3b4dec0 100644
--- a/src/Luban.Job.Db/Source/Defs/TTypeTemplateExtends.cs
+++ b/src/Luban.Job.Db/Source/Defs/TTypeTemplateExtends.cs
@@ -12,6 +12,11 @@ namespace Luban.Job.Db.Defs
             return type.Apply(DbCsDefineTypeVisitor.Ins);
         }
 
+        public static string DbCsReadonlyDefineType(TType type)
+        {
+            return type.Apply(DbCsReadOnlyDefineTypeVisitor.Ins);
+        }
+
         public static string CsImmutableType(TType type)
         {
             return type.Apply(ImmutableTypeName.Ins);
diff --git a/src/Luban.Job.Db/Source/Generate/SyncCsRender.cs b/src/Luban.Job.Db/Source/Generate/SyncCsRender.cs
index 9da45ea..bc3886d 100644
--- a/src/Luban.Job.Db/Source/Generate/SyncCsRender.cs
+++ b/src/Luban.Job.Db/Source/Generate/SyncCsRender.cs
@@ -43,13 +43,21 @@ namespace Luban.Job.Db.Generate
     fields = x.fields
     hierarchy_fields = x.hierarchy_fields
     is_abstract_type = x.is_abstract_type
+    readonly_name = ""IReadOnly"" + name
 }}
 using Bright.Serialization;
 
 namespace {{x.namespace_with_top_module}}
 {
+
+public interface {{readonly_name}} {{if parent_def_type}}: IReadOnly{{x.parent}} {{end}}
+{
+    {{~ for field in fields~}}
+        {{db_cs_readonly_define_type field.ctype}} {{field.cs_style_name}} {get;}
+    {{~end~}}
+}
    
-public {{x.cs_class_modifier}} class {{name}} : {{if parent_def_type}} {{x.parent}} {{else}} Bright.Transaction.TxnBeanBase {{end}}, Bright.Transaction.IUnsafeBean
+public {{x.cs_class_modifier}} class {{name}} : {{if parent_def_type}} {{x.parent}} {{else}} Bright.Transaction.TxnBeanBase {{end}}, {{readonly_name}} , Bright.Transaction.IUnsafeBean
 {
     {{~ for field in fields~}}
         {{if is_abstract_type}}protected{{else}}private{{end}} {{db_cs_define_type field.ctype}} {{field.internal_name}};
@@ -63,6 +71,7 @@ public {{x.cs_class_modifier}} class {{name}} : {{if parent_def_type}} {{x.paren
     }
 
     {{~ for field in fields~}}
+        {{ctype = field.ctype}}
         {{~if has_setter field.ctype~}}
 
     private sealed class {{field.log_type}} :  Bright.Transaction.FieldLogger<{{name}}, {{db_cs_define_type field.ctype}}>
@@ -142,6 +151,12 @@ public {{x.cs_class_modifier}} class {{name}} : {{if parent_def_type}} {{x.paren
 
          public {{db_cs_define_type field.ctype}} {{field.cs_style_name}} => {{field.internal_name}};
         {{~end~}}
+
+        {{~if ctype.bean || ctype.element_type ~}}
+        {{db_cs_readonly_define_type ctype}} {{readonly_name}}.{{field.cs_style_name}} => {{field.internal_name}};
+        {{~else if ctype.is_map~}}
+        {{db_cs_readonly_define_type ctype}} {{readonly_name}}.{{field.cs_style_name}} => new Bright.Transaction.Collections.PReadOnlyMap<{{db_cs_readonly_define_type ctype.key_type}}, {{db_cs_readonly_define_type ctype.value_type}}, {{db_cs_define_type ctype.value_type}}>({{field.internal_name}});
+        {{~end~}}
     {{~end~}}
 
     {{~if is_abstract_type~}}
@@ -273,14 +288,14 @@ public sealed class {{name}}
         Table.Put(key, value);
     }
 
-    public static {{db_cs_define_type value_ttype}} Select({{db_cs_define_type key_ttype}} key)
+    public static {{db_cs_readonly_define_type value_ttype}} Select({{db_cs_define_type key_ttype}} key)
     {
         return Table.Select(key);
     }
 
-    public static ValueTask<{{db_cs_define_type value_ttype}}> SelectAsync({{db_cs_define_type key_ttype}} key)
+    public static ValueTask<{{db_cs_readonly_define_type value_ttype}}> SelectAsync({{db_cs_define_type key_ttype}} key)
     {
-        return Table.SelectAsync<{{db_cs_define_type value_ttype}}>(key);
+        return Table.SelectAsync<{{db_cs_readonly_define_type value_ttype}}>(key);
     }
 }
 }
diff --git a/src/Luban.Job.Db/Source/TypeVisitors/DbCsReadOnlyDefineTypeVisitor.cs b/src/Luban.Job.Db/Source/TypeVisitors/DbCsReadOnlyDefineTypeVisitor.cs
new file mode 100644
index 0000000..4efac45
--- /dev/null
+++ b/src/Luban.Job.Db/Source/TypeVisitors/DbCsReadOnlyDefineTypeVisitor.cs
@@ -0,0 +1,36 @@
+using Luban.Job.Common.Types;
+using Luban.Job.Common.TypeVisitors;
+
+namespace Luban.Job.Db.TypeVisitors
+{
+    class DbCsReadOnlyDefineTypeVisitor : DecoratorFuncVisitor<string>
+    {
+        public static DbCsReadOnlyDefineTypeVisitor Ins { get; } = new DbCsReadOnlyDefineTypeVisitor();
+
+
+        public override string DoAccept(TType type)
+        {
+            return type.Apply(CsDefineTypeName.Ins);
+        }
+
+        public override string Accept(TBean type)
+        {
+            return $"{type.Bean.NamespaceWithTopModule}.IReadOnly{type.Bean.Name}";
+        }
+
+        public override string Accept(TList type)
+        {
+            return $"System.Collections.Generic.IReadOnlyList<{type.ElementType.Apply(this)}>";
+        }
+
+        public override string Accept(TSet type)
+        {
+            return $"System.Collections.Generic.IReadOnlySet<{type.ElementType.Apply(this)}>";
+        }
+
+        public override string Accept(TMap type)
+        {
+            return $"System.Collections.Generic.IReadOnlyDictionary<{type.KeyType.Apply(this)}, {type.ValueType.Apply(this)}>";
+        }
+    }
+}