AutoMappic

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Porting from AutoMapper to AutoMappic ​

AutoMappic was designed to be a high-performance, Native AOT-friendly replacement for AutoMapper. Transitioning an existing codebase is usually as simple as swapping the namespace and enabling Roslyn Interceptors.

Why Migrate? ​

  • Native AOT Ready: AutoMapper relies heavily on reflection and dynamic code generation (System.Reflection.Emit), which are incompatible with Native AOT. AutoMappic generates all mapping logic as static C# classes at compile time.
  • Startup Performance: AutoMappic eliminates the need for reflection-based profile scanning at startup.
  • Compile-Time Verification: Potential mapping issues (ambiguous paths, missing members) are reported as compiler diagnostics rather than runtime exceptions.

1. NuGet Package Replacement ​

In your project file (.csproj), remove the AutoMapper packages and add AutoMappic.

xml
<ItemGroup>
  <!-- Remove these -->
  <!-- <PackageReference Include="AutoMapper" Version="..." /> -->
  <!-- <PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="..." /> -->

  <!-- Add this -->
  <PackageReference Include="AutoMappic" Version="0.5.0" />
</ItemGroup>

2. Enable Interceptors ​

AutoMappic uses Roslyn Interceptors to achieve its zero-reflection magic. You must enable the interceptors namespace in your project file so the compiler can reroute mapper.Map calls to the generated code.

xml
<PropertyGroup>
  <InterceptorsNamespaces>$(InterceptorsNamespaces);AutoMappic.Generated</InterceptorsNamespaces>
</PropertyGroup>

3. Global Usings ​

If your project uses C# GlobalUsings.cs, update it to point to AutoMappic. AutoMappic mirrors the standard AutoMapper API surface (IMapper, Profile, CreateMap, etc.).

csharp
// GlobalUsings.cs
global using AutoMappic;
// global using AutoMapper.QueryableExtensions; // No longer needed, included in AutoMappic

4. Dependency Injection ​

The Compatible Way (Bridge) ​

AutoMappic includes an AddAutoMapper extension for IServiceCollection to keep your existing registration code working:

csharp
// Still works!
builder.Services.AddAutoMapper(Assembly.GetExecutingAssembly());

The Optimized Way (Native AOT) ​

For the best performance and smallest binary size, use the source-generated registration method. This method is generated at compile-time and contains a hard-coded list of all your profiles.

csharp
// Recommended
builder.Services.AddAutoMappic();

5. Feature Compatibility ​

AutoMapper FeatureAutoMappic EquivalentStatus
CreateMap<S, D>()CreateMap<S, D>()Supported
ForMember(opt => ...)ForMember(opt => ...)Supported
ReverseMap()ReverseMap()Supported
ProjectTo<T>().ProjectTo<T>()Supported (Intercepted)
BeforeMap / AfterMap.BeforeMap() / .AfterMap()Supported
ITypeConverterConvertUsing<T>()Supported
ValueResolverMapFrom<TResolver>()Supported

Troubleshooting Common Issues ​

AM0002: Ambiguous Mapping ​

AutoMappic is stricter than AutoMapper regarding ambiguous paths. If a property UserCity on a DTO could be mapped from either a direct property UserCity or a flattened property User.City, AutoMappic will prioritize the direct match but may warn you if it's unclear.

AM0008: Unsupported ProjectTo Feature ​

Because ProjectTo generates Entity Framework-compatible Expression trees, it does not support procedural logic like BeforeMap or AfterMap. If your mapping uses these, AutoMappic will report a diagnostic suggesting you use Map<T> instead of ProjectTo<T>.