GH-4272: Allows ValueTypesto be used as Duplicated Fields

src/Marten/Linq/Members/DuplicatedField.cs

@@ -128,8 +128,7 @@ public void PlaceValueInDictionaryForContainment(Dictionary<string, object> dict
     /// </summary>
     public NpgsqlDbType DbType { get; set; }
 
-
-    internal UpsertArgument UpsertArgument => new()
+    internal virtual UpsertArgument UpsertArgument => new()
     {
         Arg = "arg_" + ColumnName.ToLower(),
         Column = ColumnName.ToLower(),
@@ -167,7 +166,7 @@ string IQueryableMember.SelectorForDuplication(string pgType)
         throw new NotSupportedException();
     }
 
-    public ISqlFragment CreateComparison(string op, ConstantExpression constant)
+    public virtual ISqlFragment CreateComparison(string op, ConstantExpression constant)
     {
         if (constant.Value == null)
         {

src/Marten/Linq/Members/DuplicatedValueTypeField.cs

@@ -0,0 +1,41 @@
+using System.Linq.Expressions;
+using JasperFx.Core.Reflection;
+using Marten.Schema.Arguments;
+using Weasel.Core;
+using Weasel.Postgresql.SqlGeneration;
+
+namespace Marten.Linq.Members;
+
+public class DuplicatedValueTypeField: DuplicatedField
+{
+    public DuplicatedValueTypeField(EnumStorage enumStorage, QueryableMember innerMember, ValueTypeInfo valueTypeInfo
+        , bool useTimestampWithoutTimeZoneForDateTime = true, bool notNull = false): base(
+        enumStorage, innerMember, useTimestampWithoutTimeZoneForDateTime, notNull)
+    {
+        ValueTypeInfo = valueTypeInfo;
+    }
+
+    public ValueTypeInfo ValueTypeInfo { get; }
+
+    internal override UpsertArgument UpsertArgument
+    {
+        get
+        {
+            var upsertArgument = base.UpsertArgument;
+
+            if (InnerMember.Member.GetRawMemberType()!.IsNullable())
+            {
+                upsertArgument.ParameterValue = $"{InnerMember.Member.Name}.Value.{ValueTypeInfo.ValueProperty.Name}";
+            }
+
+            upsertArgument.ParameterValue = $"{InnerMember.Member.Name}.{ValueTypeInfo.ValueProperty.Name}";
+
+            return upsertArgument;
+        }
+    }
+
+    public override ISqlFragment CreateComparison(string op, ConstantExpression constant)
+    {
+        return InnerMember.CreateComparison(op, constant);
+    }
+}

src/Marten/Schema/DocumentMapping.cs

@@ -19,6 +19,7 @@
 using Marten.Schema.Indexing.Unique;
 using Marten.Storage;
 using Marten.Storage.Metadata;
+using Marten.Util;
 using NpgsqlTypes;
 using Weasel.Core;
 using Weasel.Postgresql;
@@ -741,20 +742,33 @@ public DuplicatedField DuplicateField(string memberName, string? pgType = null,
 
         var enumStorage = StoreOptions.Advanced.DuplicatedFieldEnumStorage;
         var dateTimeStorage = StoreOptions.Advanced.DuplicatedFieldUseTimestampWithoutTimeZoneForDateTime;
-        var duplicate = member is ValueCollectionMember collectionMember
-            ? new DuplicatedArrayField(enumStorage, collectionMember, dateTimeStorage, notNull)
-            : new DuplicatedField(enumStorage, (QueryableMember)member, dateTimeStorage, notNull);
+
+        DuplicatedField duplicatedField;
+
+        if (member is ValueCollectionMember collectionMember)
+        {
+            duplicatedField = new DuplicatedArrayField(enumStorage, collectionMember, dateTimeStorage, notNull);
+        }
+        else if (member.IsGenericInterfaceImplementation(typeof(IValueTypeMember<,>)))
+        {
+            var valueTypeInfo = StoreOptions.ValueTypes.FirstOrDefault(x => x.OuterType == member.MemberType)!;
+            duplicatedField = new DuplicatedValueTypeField(enumStorage, member, valueTypeInfo, notNull);
+        }
+        else
+        {
+            duplicatedField = new DuplicatedField(enumStorage, member, dateTimeStorage, notNull);
+        }
 
         if (pgType.IsNotEmpty())
         {
-            duplicate.PgType = pgType;
+            duplicatedField.PgType = pgType;
         }
 
-        QueryMembers.ReplaceMember(member.Member, duplicate);
+        QueryMembers.ReplaceMember(member.Member, duplicatedField);
 
-        _duplicates.Add(duplicate);
+        _duplicates.Add(duplicatedField);
 
-        return duplicate;
+        return duplicatedField;
     }
 
     public DuplicatedField DuplicateField(MemberInfo[] members, string? pgType = null, string? columnName = null,
@@ -786,9 +800,22 @@ public DuplicatedField DuplicateField(MemberInfo[] members, string? pgType = nul
 
         var enumStorage = StoreOptions.Advanced.DuplicatedFieldEnumStorage;
         var dateTimeStorage = StoreOptions.Advanced.DuplicatedFieldUseTimestampWithoutTimeZoneForDateTime;
-        var duplicatedField = member is ValueCollectionMember collectionMember
-            ? new DuplicatedArrayField(enumStorage, collectionMember, dateTimeStorage, notNull)
-            : new DuplicatedField(enumStorage, (QueryableMember)member, dateTimeStorage, notNull);
+
+        DuplicatedField duplicatedField;
+
+        if (member is ValueCollectionMember collectionMember)
+        {
+            duplicatedField = new DuplicatedArrayField(enumStorage, collectionMember, dateTimeStorage, notNull);
+        }
+        else if (member.IsGenericInterfaceImplementation(typeof(IValueTypeMember<,>)))
+        {
+            var valueTypeInfo = StoreOptions.ValueTypes.FirstOrDefault(x => x.OuterType == member.MemberType)!;
+            duplicatedField = new DuplicatedValueTypeField(enumStorage, (QueryableMember)member, valueTypeInfo, notNull);
+        }
+        else
+        {
+            duplicatedField = new DuplicatedField(enumStorage, (QueryableMember)member, dateTimeStorage, notNull);
+        }
 
         parent.ReplaceMember(members.Last(), duplicatedField);