JustItMap 0.1.3

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JustItMap

A lightweight, explicit, and predictable object-mapping library for .NET

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🎯 Philosophy

JustItMap follows a simple rule:

• Convention when it is obvious - automatic mapping by property name
• Explicit mapping when it is not - override with MapFrom when needed

This keeps the API small, readable, and easy to reason about while still covering the common cases you need in DTO, entity, model, and view-model transformations.

✨ Features

• ✅ Automatic mapping by property name - Convention over configuration
• ✅ Compatible type conversion - Smart type conversion when needed
• ✅ Nested object mapping - Handles complex object hierarchies
• ✅ Collection mapping - Map lists, arrays, and enumerables
• ✅ Explicit override - Use MapFrom for custom mappings
• ✅ Explicit ignore - Skip properties with IgnoreMap
• ✅ Lightweight - Minimal dependency footprint
• ✅ Works standalone - No DI container required (but integrates well)
• ✅ Multi-SDK support - .NET 8.0, 9.0, 10.0

📦 Installation

NuGet Package

dotnet add package JustItMap

Or via NuGet Package Manager:

Install-Package JustItMap

Supported Frameworks

• .NET 8.0 and later
• .NET 9.0
• .NET 10.0

🚀 Quick Start

Basic mapping

var user = new User
{
    Id = 42,
    Name = "Ada Lovelace",
    Email = "ada@example.com"
};

var dto = user.MapTo<UserDto>();
// dto.Id = 42
// dto.Name = "Ada Lovelace"
// dto.Email = "ada@example.com"

Explicit mapping override

Use MapFrom to explicitly map properties when names don't match:

public class UserDtoProfile : MappingProfile<User, UserDtoWithFullName>
{
    public UserDtoProfile()
    {
        MapFrom(
            destination => destination.FullName,
            source => source.FirstName + " " + source.LastName
        );
    }
}

var source = new User
{
    FirstName = "Ada",
    LastName = "Lovelace"
};

var result = source.MapTo<UserDtoWithFullName>();
// result.FullName == "Ada Lovelace"

Ignoring a property

Use IgnoreMap attribute to skip properties during mapping:

public class UserDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    
    [IgnoreMap]
    public string Password { get; set; }
}

var source = new User
{
    Id = 7,
    Name = "Grace",
    Password = "secret"
};

var dto = source.MapTo<UserDto>();
// Password is skipped (remains null or default)

Collection mapping

var users = new[]
{
    new User { Id = 1, Name = "Alan" },
    new User { Id = 2, Name = "Linus" }
};

var dtos = users.MapToCollection<UserDto>();
// Returns IEnumerable<UserDto>

🎯 Mapping Priority Order

The mapping engine follows this priority (highest to lowest):

1. IgnoreMap - Properties marked to be ignored
2. Explicit MapFrom - Custom mapping rules in MappingProfile
3. Convention mapping - Automatic mapping by property name and compatible types

This ensures that explicit rules always win over implicit behavior.

🔧 Dependency Injection

Register JustItMap in your application's DI container:

services.AddJustItMap();

Then inject and use:

public class MyService
{
    private readonly IMapper _mapper;
    
    public MyService(IMapper mapper)
    {
        _mapper = mapper;
    }
    
    public UserDto MapUser(User user)
    {
        return _mapper.Map<UserDto>(user);
    }
}

📖 Documentation

For detailed documentation and advanced usage, see the full documentation.

🧪 Testing

This repository uses xUnit for testing.

To run tests locally:

dotnet test -c Release

⚖️ License

MIT License - see LICENSE file for details.

👥 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📞 Support

For issues and questions, please use the GitHub Issues page.

dotnet run --project tests/JustItMap.Tests

License

MIT