Asynchronous Lifecycle Hooks: BeforeMap & AfterMap

AutoMappic v0.5.0 introduces Asynchronous Lifecycle Hooks, allowing you to perform I/O-bound operations during the mapping process without blocking.

The Dual-Emission Engine

AutoMappic's unique Dual-Emission Engine generates both synchronous and asynchronous versions of every mapping.

When you configure a BeforeMapAsync or AfterMapAsync, the generator handles the complex state-matching for you.

Basic Usage

To add a lifecycle hook, use .BeforeMap() or .AfterMap() inside your CreateMap configuration:

CreateMap<Order, OrderDto>()
    .BeforeMapAsync(async (src, dest) => 
    {
        // Fetch audit logs as part of the mapping
        dest.AuditLog = await _auditService.GetLastLogAsync(src.Id);
    })
    .AfterMap((src, dest) => 
    {
        // Synchronous cleanup logic
        dest.ProcessedAt = DateTime.UtcNow;
    });

How it Works

When you call await mapper.MapAsync<Order, OrderDto>(order), the generated code looks something like this:

// Auto-generated by AutoMappic
public static async Task<OrderDto> MapToOrderDtoAsync(this Order source, CancellationToken ct = default)
{
    var result = new OrderDto();
    
    // 1. Static Profile Cache access (Zero-reflection singleton)
    var profile = Cache<OrderProfile>.Instance;

    // 2. Lifecycle Hooks
    profile.BeforeMap(source, result); // Sync first
    await profile.BeforeMapAsync(source, result).ConfigureAwait(false); // Then Async

    // 3. Property mapping...
    result.Id = source.Id;
    
    // 4. Finalize Hooks
    profile.AfterMap(source, result);
    
    return result;
}

Mixing Sync and Async

You can mix BeforeMap (sync) and BeforeMapAsync (async). AutoMappic ensures that:

1. If MapAsync is called: Both sync and async hooks are executed (async hooks are awaited).
2. If Map (sync) is called: ONLY sync hooks are executed (async hooks are skipped to prevent blocking deadlocks).

Sustainability & Deadlock Prevention

AutoMappic v0.5.0 has been built with Sustainable Async Engineering. Every generated await in the source code uses .ConfigureAwait(false) to ensure you never have a deadlock in WPF, WinForms, or legacy ASP.NET applications.

Summary

Hook Type	Native AOT	Use Case
BeforeMap	100%	Pre-mapping normalization / clearing values.
BeforeMapAsync	100%	Fetching related entities from a database.
AfterMap	100%	Finalizing timestamps / complex derivation.
AfterMapAsync	100%	Logging or auditing the mapping event asynchronously.