Standalone Mapping: The [AutoMap] Attribute

AutoMappic v0.6.0 introduces Standalone Mappings, allowing you to define mapping configurations directly on your DTO or Entity classes using the [AutoMap] attribute. This eliminates the need to create a separate Profile class for simple mappings and keeps your codebase highly localized.

1. Basic Usage

By decorating your destination class with [AutoMap], the source generator automatically creates a mapping from the specified source type.

using AutoMappic;

public class EmployeeSource { public int Id { get; set; } public string Name { get; set; } }

[AutoMap(typeof(EmployeeSource))]
public partial class EmployeeDto 
{ 
    public int Id { get; set; } 
    public string Name { get; set; } 
}

WARNING

IMPORTANT: Standalone mapping classes MUST be marked as partial. AutoMappic needs this to inject common mapping interfaces (like IMapTo<T>) into your type at compile-time.

2. Advanced Configuration

The [AutoMap] attribute supports several configuration options found in traditional Profiles:

• ReverseMap: Automatically generates a mapping in the opposite direction.
• DeleteOrphans: When mapping collections of Entities, removes items from the destination collection that do not exist in the source.
• EnableIdentityManagement: Ensures object-references are preserved throughout the mapping graph.
• SourceNamingConvention / DestinationNamingConvention: Overrides the naming strategy for this specific pair.

[AutoMap(typeof(User), ReverseMap = true, EnableIdentityManagement = true)]
public partial class UserDto { ... }

3. Mapping Discovery

Standalone mappings are automatically discovered by the generator and integrated into the global IMapper registry. You can use them via standard interception just like Profile-based mappings:

var dto = _mapper.Map<UserDto>(user);

4. Comparison with Profiles

Feature	Profiles	[AutoMap]
Location	Separate class	Directly on DTO
Custom Logic	Full (.ForMember, .AfterMap)	Limited (Convention-based)
Discovery	Automatic	Automatic
Partial Required	No	Yes

Recommendation: Use [AutoMap] for 90% of your simple DTOs to reduce boilerplate. Use Profile subclasses when you need complex transformations, specific .ForMember() logic, or asynchronous lifestyle hooks.

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TIP

Need a deep dive? Check out our Standalone Mapping Tutorial for a full walkthrough, performance considerations, and IDE tips.

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