Mecesoft.ObjectMapper.DependencyInjection 1.0.0

Mecesoft.ObjectMapper.DependencyInjection

Microsoft.Extensions.DependencyInjection integration for Mecesoft.ObjectMapper.

Status: 1.0.0. Not published to NuGet yet.

Installation

Reference Mecesoft.ObjectMapper.DependencyInjection. The core Mecesoft.ObjectMapper package remains free of DI dependencies and is brought in transitively by this package.

Registration

using Microsoft.Extensions.DependencyInjection;
using Mecesoft.ObjectMapper;

var services = new ServiceCollection();

services.AddMecesoftObjectMapper(cfg =>
{
    cfg.CreateMap<Customer, CustomerDto>();
});

using var provider = services.BuildServiceProvider();
var mapper = provider.GetRequiredService<IMapper>();

• IMapper is registered as a singleton.
• By default, the configuration is created once when the mapper is first resolved.
• When AssertConfigurationIsValid is enabled, the configuration is built and validated during AddMecesoftObjectMapper (application startup) instead.
• The mapper can be injected into singleton, scoped or transient services.
• ReverseMap() is available in the configuration action:

services.AddMecesoftObjectMapper(cfg =>
    cfg.CreateMap<Customer, CustomerDto>().ReverseMap());

Options

services.AddMecesoftObjectMapper(
    cfg => cfg.CreateMap<Customer, CustomerDto>(),
    new MapperConfigurationOptions
    {
        MaxDepth = 256,
        MaxCollectionSize = 50_000
    });

Options are captured when AddMecesoftObjectMapper is called.

Profiles, scanning and validation

using Mecesoft.ObjectMapper.DependencyInjection;

services.AddMecesoftObjectMapper(
    cfg => cfg.CreateMap<Customer, CustomerDto>(),
    options =>
    {
        options.AddProfile<CustomerProfile>();
        options.AddProfile(new OrderProfile());
        options.AssertConfigurationIsValid = true;

        options.Configuration.MaxDepth = 256;
        options.Configuration.MaxCollectionSize = 50_000;
    });

Assembly scanning is an explicit opt-in:

services.AddMecesoftObjectMapper(
    cfg => cfg.CreateMap<Customer, CustomerDto>(),
    options => options.AddProfilesFromAssembly(typeof(CustomerProfile).Assembly));

• Explicit profiles are applied in registration order.
• Profile scanning discovers concrete Profile types with a public parameterless constructor and sorts them by full name using ordinal comparison.
• Duplicate maps are rejected by the core library when the configuration is built.
• AssertConfigurationIsValid is opt-in. When enabled, it builds and validates the configuration during AddMecesoftObjectMapper; invalid configuration throws at startup, before the service provider is built and before the mapper is first resolved.
• Startup validation failure leaves the IServiceCollection without the mapper registration. Configuration actions may still have observed user-side side effects because they run during registration.
• Reverse maps created by ReverseMap() are included in validation and missing reverse nested/collection maps are reported with a (reverse) marker.
• Assembly scanning uses reflection and is not NativeAOT/trimming safe; prefer explicit profile registration for trimmed or NativeAOT applications. Core mapping remains reflection-based even with explicit profiles.

Startup validation

The DI package does not depend on ASP.NET Core hosting abstractions. Validation is performed at registration, which is the startup phase for a typical application:

services.AddMecesoftObjectMapper(
    cfg => cfg.CreateMap<Customer, CustomerDto>().ReverseMap(),
    options => options.AssertConfigurationIsValid = true);

This makes an invalid configuration fail while the application is configuring services, rather than on the first request that resolves IMapper. It does not require IHostedService or a framework-specific integration package.

Duplicate and existing registrations

AddMecesoftObjectMapper is intentionally non-overriding:

• A second call on the same IServiceCollection throws InvalidOperationException.
• If an IMapper service is already registered by another component, registration throws InvalidOperationException instead of replacing it.

Build a separate service collection if different mapper configurations are required.

Configuration snapshot

The type maps and member options are snapshotted by CreateMapper. With startup validation, the singleton mapper and snapshot are created during registration; otherwise it is created on first resolution. Changes to the configuration after mapper creation do not affect that mapper. The DI registration options are frozen when AddMecesoftObjectMapper is called.

AOT and trimming

The DI package is not a NativeAOT/trimming guarantee. AddProfilesFromAssembly is annotated with [RequiresUnreferencedCode] because it discovers and constructs profile types by reflection. Prefer AddProfile/AddProfile<TProfile>() in trimmed or NativeAOT builds; core mapping still discovers and compiles property accessors reflectively.

License

MIT. See LICENSE.