AutoMapper to Mapper migration #10520

6 Answer(s)

• 

  0

  AI-Bot created 6 months ago

  Support Team ABP Agent

  • The compiler error you’re seeing (CS8795: “Partial method … must have an implementation part because it has accessibility modifiers”) happens when the Mapperly source generator doesn’t run / doesn’t generate code for that [Mapper] class.
    In that case, your public override partial … Map(...) declarations remain “unimplemented”, and C# reports CS8795.

  • In ABP v10, the correct pattern (public override partial ...) is valid only if:

    1. the project references Mapperly (and ABP’s Mapperly integration), and
    2. the Mapperly source generator is executed during build, producing the other part of the partial class.

  Fix (step-by-step)

  1. Ensure you installed ABP Mapperly integration package in the project where the mapper class exists:

     • Volo.Abp.Mapperly

  2. Ensure the module registers Mapperly (at least in that layer):

  using Volo.Abp.Modularity;
     using Volo.Abp.Mapperly;
  
     [DependsOn(typeof(AbpMapperlyModule))]
     public class YourModule : AbpModule
     {
         public override void ConfigureServices(ServiceConfigurationContext context)
         {
             context.Services.AddMapperlyObjectMapper<YourModule>();
             // or (if you want it as default provider)
             // context.Services.AddMapperlyObjectMapper();
         }
     }
  

  3. Ensure the Mapperly generator package is present (directly or transitively). If CS8795 persists, add it explicitly to the same .csproj where the mapper lives:

  <ItemGroup>
       <PackageReference Include="Riok.Mapperly" Version="*" PrivateAssets="all" />
     </ItemGroup>
  

  Then Clean + Rebuild (not just Build).

  4. Make sure the mapper class is in a buildable project (not a shared project with generation disabled) and that you are not disabling analyzers/source generators (e.g., <RunAnalyzers>false</RunAnalyzers> or similar build settings).

  After these, the generated file for your mapper should appear under Dependencies → Analyzers → Riok.Mapperly (VS) / Generated files, and the CS8795 error will disappear.

  • https://abp.io/docs/10.0/release-info/migration-guides/AutoMapper-To-Mapperly
  • https://abp.io/docs/latest/framework/infrastructure/object-to-object-mapping
  • https://abp.io/community/articles/l9f5ii8s

  ---

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• 

  0

  DominaTang created 6 months ago

  I checked all steps you mentioned, under Dependencies -> Analyzers -> Rick.Mapperly, there is empty class generated

  public partial class IdentityUserToIdentityUserEtoMapper
  {
  }
  

  }

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  0

  maliming created 6 months ago

  Support Team Fullstack Developer

  hi

  What is your VS version?

  targeting .NET 10 is only officially supported in Visual Studio 2026 and later versions

  Thanks.

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  0

  DominaTang created 6 months ago

  I tried Visual Studio 2026 Enterprise V18.4.0 and Visual Studio 2022 17.14.28

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  0

  maliming created 6 months ago

  Support Team Fullstack Developer

  hi

  Can you build the project using the dotnet build command?

  I think this is related to the VS version. maybe you can upgrade vs to latest version

  Related to https://github.com/riok/mapperly/issues/2134

  Thanks.

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  0

  DominaTang created 6 months ago

  Finally figure out the solution, I am using VS 2026 or command line to build, still got same build error. First make sure the two partial override has no any implementation, public override partial IdentityUserEto Map(IdentityUser source); public override partial void Map(IdentityUser source, IdentityUserEto destination);

  And add these lines to project file: <PropertyGroup> <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles> <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath> </PropertyGroup> <ItemGroup> <Compile Remove="$(CompilerGeneratedFilesOutputPath)/**/*.cs" /> </ItemGroup>

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