using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

using System.Diagnostics;

using System.Collections.ObjectModel;

using System.Runtime.Serialization;

using System.Xml.Serialization;

using System.Reflection;

​

using ProtoBuf.Meta;

using ProtoBuf;

​

using System.Globalization;

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/75126034/protobuf-net-grpc-system-notsupportedexception-specified-method-is-not-suppo

​

/// <summary>

/// A common class for results returned by the services. No data is returned here.

/// </summary>

[ProtoContract]

public class GrpcServiceResult

{

    [ProtoMember(1)]

    public bool Success { get; set; }

​

    [ProtoMember(2)]

    public string Message { get; set; } = null!;

​

    private GrpcServiceResult() { }

​

    public GrpcServiceResult(bool success, string message = "")

    {

        Success = success;

        Message = message;

    }

}

​

[ProtoContract]

public class GrpcServiceResult<T> where T : class

{

    [ProtoMember(1)]

    public bool Success { get; set; }

​

    [ProtoMember(2)]

    public string Message { get; set; } = null!;

​

    [ProtoMember(3)]

    public T Data { get; set; } = null!;

​

    private GrpcServiceResult() { }

    public GrpcServiceResult(bool success, T result = null!, string message = "")

    {

        Success = success;

        Message = message;

        Data = result;

    }

}

​

[ProtoContract]

public class PagedResult<T> where T : class

{

    [ProtoMember(1)]

    public int CurrentPage { get; set; }

​

    [ProtoMember(2)]

    public int PageCount { get; set; }

​

    [ProtoMember(3)]

    public int PageSize { get; set; }

​

    [ProtoMember(4)]

    public int RowCount { get; set; }

​

    [ProtoIgnore]

    public int FirstRowOnPage

    {

        get { return (CurrentPage - 1) * PageSize + 1; }

    }

​

    [ProtoIgnore]

    public int LastRowOnPage

    {

        get { return Math.Min(CurrentPage * PageSize, RowCount); }

    }

​

    [ProtoMember(5)]

    public IList<T> Results { get; set; }

​

    public PagedResult()

    {

        Results = new List<T>();

    }

}

​

[ProtoContract]

public class SystemItemsRequestContract

{

    [ProtoMember(1)]

    public string SearchPattern { get; set; } = null!;

​

    [ProtoMember(2)]

    public int PartnerId { get; set; }

​

    [ProtoMember(3)]

    public int SearchField { get; set; }

​

    [ProtoMember(4)]

    public int Page { get; set; }

​

    [ProtoMember(5)]

    public int Count { get; set; }

}

​

[ProtoContract]

public class SystemItemsResponseContract : ItemInfoSyncResponseContract

{

    [ProtoMember(1)]

    public int Id { get; set; }

​

    // I have built a custom surrogate for this one, and even if I remove it, I'm getting the same error

    [ProtoMember(2)]

    public DateTimeOffset? InsertedOn { get; set; }

​

    //...

​

#if false

    // This was missing form the question

    [ProtoMember(7)]

    public ESellingType SoldAs { get; set; }

#endif

    //...

​

    // List of the same class

    [ProtoMember(10)]

    public List<SystemItemsResponseContract> Packs { get; set; }

}

​

[ProtoContract]

[ProtoInclude(1000, typeof(SystemItemsResponseContract))]

public class ItemInfoSyncResponseContract

{

    //...

​

    [ProtoMember(2)]

    public List<ItemBarcode> Barcodes { get; set; } = null!;

​

​

    //...

​

    [ProtoMember(6)]

    public List<string> Images { get; set; } = null!;

​

    //... other properties are solely string, double, double?, int

​

}

​

​

[ProtoContract]

public class ItemBarcode

{

    [ProtoMember(1)]

    public string Barcode { get; set; } = null!;

​

    [ProtoMember(2)]

    public string Check { get; set; } = null!;

}

​

#if false

public interface IDataReadService

{

    // ...

​

    /// <summary>

    /// Get the data entry item structure.

    /// </summary>

    /// <param name="data"></param>

    /// <returns></returns>

    [OperationContract]

    Task<GrpcServiceResult<PagedResult<SystemItemsResponseContract>>> GetSystemItems(SystemItemsRequestContract contract);

}

#endif

​

// Surrogate from this answer https://stackoverflow.com/a/7046868

// By https://stackoverflow.com/users/23354/marc-gravell

// To https://stackoverflow.com/questions/7046506/can-i-serialize-arbitrary-types-with-protobuf-net

[ProtoContract]

public class DateTimeOffsetSurrogate

{

    [ProtoMember(1)]

    public string DateTimeString { get; set; }

​

    public static implicit operator DateTimeOffsetSurrogate(DateTimeOffset value)

    {

        return new DateTimeOffsetSurrogate {DateTimeString = value.ToString("u")};

    }

​

    public static implicit operator DateTimeOffset(DateTimeOffsetSurrogate value)

    {

        return DateTimeOffset.Parse(value.DateTimeString);

    }

}

​

public class TestClass

{

    public static T RoundTrip<T>(T input)

    {

        using var stream = new MemoryStream();

​

        Serializer.Serialize(stream, input);

​

        stream.Position = 0;

​

        var output = Serializer.Deserialize<T>(stream);

​

        return output;

    }

    public static void Test()

    {

        RuntimeTypeModel.Default.Add(typeof(DateTimeOffset), false).SetSurrogate(typeof(DateTimeOffsetSurrogate));

        RoundTrip(new SystemItemsRequestContract());

        RoundTrip(new SystemItemsResponseContract());

        RoundTrip(new PagedResult<SystemItemsResponseContract>());

        var result = RoundTrip(new GrpcServiceResult<PagedResult<SystemItemsResponseContract>>(false, new() { Results = { new(), new() { InsertedOn = default(DateTimeOffset) }}}, "foo"));

​

        Console.WriteLine("Round-tripped {0}:", result);

        Console.WriteLine(System.Text.Json.JsonSerializer.Serialize(result, new System.Text.Json.JsonSerializerOptions { WriteIndented = true }));

    }

}

​

public static class ProtobufNetExtensions

{

}

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version);

        Console.WriteLine("protobuf-net Serializer version: " + typeof(ProtoBuf.Serializer).Assembly.FullName);

        Console.WriteLine("protobuf-net ProtoReader version: " + typeof(ProtoBuf.ProtoReader).Assembly.FullName + "\n");

        TestClass.Test();

    }

}

​

#if false

I tried to reproduce your problem in a standalone fiddle here: https://dotnetfiddle.net/WjHiRP.  I found two problems.  1) You must use a surrogate for `DateTimeOffset` as shown in [this answer](https://stackoverflow.com/a/7046868) by Marc Gravell to [Can I serialize arbitrary types with protobuf-net?](https://stackoverflow.com/q/7046506).  2) You must have a parameterless constructor for `GrpcServiceResult<T>`.  It can be private.  See https://dotnetfiddle.net/5TFK95.  Does that fix your problem?  If not, any chance you could fork my fiddle and reproduce it standalone?

#endif

​