Design and Architecture

Richard Deeming wrote:

Purists frown on it,

interface IUnitOfWork : IDisposable
{
    void Save();
    Task SaveAsync();
}

// NB: Could implement the IUnitOfWork interface directly on the FalconContext class.
class FalconContextUnitOfWork : IUnitOfWork
{
    private readonly FalconContext _context;
    
    public FalconContextUnitOfWork(FalconContext context)
    {
        _context = context;
    }
    
    public void Save()
    {
        _context.SaveChanges();
    }
    
    public Task SaveAsync()
    {
        return _context.SaveChangesAsync();
    }
    
    public void Dispose()
    {
        _context.Dispose();
    }
}

interface IBizObject : IDisposable
{
    void AddProject(Project entity);
}

class BizObject : IBizObject
{
    private readonly IProjectsRepository _projectsRepository;
    private readonly IProjectsTaskRepository _projectsTaskRepository;
    private readonly IUnitOfWork _unitOfWork;
    
    public BizObject(IProjectsRepository projectsRepository, IProjectsTaskRepository projectsTaskRepository, IUnitOfWork unitOfWork)
    {
        _projectsRepository = projectsRepository;
        _projectsTaskRepository = projectsTaskRepository;
        _unitOfWork = _unitOfWork;
    }
    
    public void AddProject(Project entity)
    {
        if (_projectsRepository.FindProjectsByName(entity.ProjectName).Any())
        {
            throw new DuplicateProjectException(entity.ProjectName);
        }
        
        _projectsRepository.Add(entity);

        foreach (var task in entity.Tasks)
        {
            _projectsTaskRepository.Add(task);
        }
        
        _unitOfWork.Save();
    }
    
    public void Dispose()
    {
        _unitOfWork.Dispose();
    }
}

public class ProjectsController : ApiController
{
    private IBizObject _bo;
    
    public ProjectsController(IBizObject bo)
    {
        _bo = bo;
    }

    public IHttpActionResult AddProject(Project entity)
    {
        _bo.AddProject(entity);
        return Ok();
    }
    
    protected override void Dispose(bool disposing)
    {
        base.Dispose(disposing);
        if (disposing) _bo.Dispose();
    }
}

Richard Deeming wrote:

Register all of the concrete implementations as transient services in your DI container

1. Create or retrieve the FalconContext for the current request;
2. Create a new instance of the FalconContextUnitOfWork and repository classes, passing in the context;
3. Create a new instance of the BizObject class, passing in the repository and unit-of-work instances;
4. Create a new instance of your controller class, passing in the BizObject instance;
5. Invoke the controller action;
6. Clean up the transient / scoped instances for the request;

• Check customer credit limit
• Create an invoice header and details
• Call the Inventory portion to ensure handle inventory issues
• Call the shipping portion

Kevin Marois wrote:

These UOW's would be the classes that actually create the repos

1. Use a good standards-based query approach (like REST) so that you can build a concise base class for the DirectoryCatalog to pick up via [InheritedExport]. Trying to get fancy with specific method location (such as Dictionary<string,func<iowinrequest,object>> ControllerActions) will lead quickly to abstraction bloat and maintenance nightmares.
2. Make sure you have your authorization model de-coupled from the controller (though metadata attributes can be used to provide this in concrete implementations). This may work with WebAPI2 out of the box, but I'm not 100% positive on that count (I used a custom OWIN web server for my implementation).
3. If you're using an ORM, either make sure to resolve objects before they leave your controller, or make your data context a part of a request object that is passed to your controller actions.