HeaderMappingTest

HeaderMappingTest.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <NoWarn>1591</NoWarn>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="ServiceStack.Common" Version="5.*" />
  </ItemGroup>

</Project>

Program.cs

using System;
using System.Linq;
using System.Collections.Generic;
using System.Collections.Specialized;
using ServiceStack;
using ServiceStack.Text;

var headers = new NameValueCollection {
    [nameof(RequestDto.AName)] = "updated",
    [nameof(RequestDto.BName)] = "updated",
};
var dto = new RequestDto {
    AName = "original",
    BName = "original",
};

// GlobalRequestFilters.Add((req,res,dto) => {...
var populateValues = new Dictionary<string, object>();
typeof(RequestDto).GetProperties()
    .Where(x => x.HasAttribute<FromHeaderAttribute>())
    .Each(x => populateValues[x.Name] = headers[x.Name]);
populateValues.PopulateInstance(dto);
// });

dto.PrintDump();
/* Output:
{
    AName: original,
    BName: updated
}*/

public class FromHeaderAttribute : Attribute {}
public class RequestDto
{
    public string AName { get; set; }
    [FromHeader]
    public string BName { get; set; }
}