URF with WPF MVVM Caliburn Micro

Question

I'm using this framework: URF and Caliburn Micro to create a business WPF application.

This is the code for the CM bootstrapper:

public class Bootstrapper : BootstrapperBase
{
    private SimpleContainer container;

    public Bootstrapper()
    {
        Initialize();
    }

    protected override void Configure()
    {
        container = new SimpleContainer();

        container.Singleton();
        container.Singleton();

        container.PerRequest();
        container.AllTypesOf(Assembly.GetExecutingAssembly());

        container.PerRequest();
        container.PerRequest();
        container.PerRequest, Repository>();
        container.PerRequest();
    }

    protected override object GetInstance(Type service, string key)
    {
        var instance = container.GetInstance(service, key);
        if (instance != null)
            return instance;

        throw new InvalidOperationException(String.Format("Could not locate any instances of type {0}", service.Name));
    }

    protected override IEnumerable

garethb · Accepted Answer

I can't speak for your DI setup, as I've never used SimpleContainer (I'm using URF with Autofac). The code in URF you are unsure of is fine. Works great with Autofac and Ninject so I'm guessing SimpleContainer will be similar. But one problem I see is in the following lines of code:

SelectedAudit = await _auditService.GetCurrentAudit();
//AuditHistoryHeader = String.Format(Constants.ADMINVIEW_AUDITHISTORYHEADER, Audits.Count);

SelectedAudit.ObjectState = ObjectState.Deleted;
_auditService.Delete(SelectedAudit); // <-- This is a problem
_unitOfWorkAsync.SaveChanges();

First, you get the SelectedAudit. SelectedAudit now being tracked by entity framework. You then set the state of SelectedAudit to deleted. So far so good. All you have to do now is call Savechanges. SelectedAudit is already attached to you entity framework context and marking it's state as deleted is enough for entity framework to know to delete it. Calling Delete from your service will try attach the SelectedAudit to the context again. This will either throw an exception (most likely) or cause undesired behaviour. If you remove the line

_auditService.Delete(SelectedAudit);

it should work. Note this is the same for updates to an entity. Get the entity, make changes to it then call SaveChanges WITHOUT calling your service update method.

You should only uses the update/delete methods if you DON'T get the entity first within the same context.

As for lifetime management, default URF uses PerRequest for IDataContextAsync, IUnitOfWorkAsync and INorthwindStoredProcedures. The rest all use TransientLifetime. Stick with that and change if you need to.

EXTRA INFO I've modified my service to accept viewmodels instead of entities. This is the service I use. I like this better as it keeps better separation (IMO) between the DAL and Web layers.

public interface IService
{
    TModel Find(params object[] keyValues);
    Task Insert(TModel model);
    IEnumerable InsertRange(IEnumerable models);
    Task Update(TModel model);
    void Delete(object id);
    void Delete(TModel model);
    Task FindAsync(params object[] keyValues);
    Task FindAsync(CancellationToken cancellationToken, params object[] keyValues);
    Task DeleteAsync(params object[] keyValues);
    Task DeleteAsync(CancellationToken cancellationToken, params object[] keyValues);
}

public abstract class Service : IService where TEntity : class, IObjectState
{
    #region Private Fields

    private readonly IRepositoryAsync _repository;
    private readonly IUnitOfWorkAsync _unitOfWork;
    private readonly IMapper _mapper;

    #endregion Private Fields

    #region Constructor

    protected Service(IRepositoryAsync repository, IUnitOfWorkAsync unitOfWork, IMapper mapper)
    {
        _repository = repository;
        _unitOfWork = unitOfWork;
        _mapper = mapper;
    }

    #endregion Constructor

    public void Delete(TModel model)
    {
        _unitOfWork.RepositoryAsync().Delete(_mapper.Map(model));
        _unitOfWork.SaveChanges();
    }

    public void Delete(object id)
    {
        _unitOfWork.RepositoryAsync().Delete(id);
        _unitOfWork.SaveChanges();
    }

    public async Task DeleteAsync(params object[] keyValues)
    {
        return await DeleteAsync(CancellationToken.None, keyValues);
    }

    public async Task DeleteAsync(CancellationToken cancellationToken, params object[] keyValues)
    {
        var result = await _unitOfWork.RepositoryAsync().DeleteAsync(cancellationToken, keyValues);
        _unitOfWork.SaveChanges();
        return result;
    }

    public TModel Find(params object[] keyValues)
    {
        return _mapper.Map(_repository.Find(keyValues));
    }

    public async Task FindAsync(params object[] keyValues)
    {
        var entity = await _repository.FindAsync(keyValues);
        return _mapper.Map(entity);
    }

    public async Task FindAsync(CancellationToken cancellationToken, params object[] keyValues)
    {
        var entity = await _repository.FindAsync(cancellationToken, keyValues);
        return _mapper.Map(entity);
    }

    public async Task Insert(TModel model)
    {
        var entity = _unitOfWork.RepositoryAsync().Insert(_mapper.Map(model));
        await _unitOfWork.SaveChangesAsync();
        return _mapper.Map(entity);
    }

    public IEnumerable InsertRange(IEnumerable models)
    {
        var entities = _unitOfWork.RepositoryAsync().InsertRange(_mapper.Map>(models));
        _unitOfWork.SaveChanges();
        return _mapper.Map>(entities);
    }

    public async Task Update(TModel model)
    {
        var entity = _unitOfWork.RepositoryAsync().Update(_mapper.Map(model));
        await _unitOfWork.SaveChangesAsync();
        return _mapper.Map(entity);
    }

    public async Task UpdateFieldsOnly(TModel model, params string[] fields)
    {
        var entity = _unitOfWork.RepositoryAsync().UpdateFieldsOnly(_mapper.Map(model), fields);
        await _unitOfWork.SaveChangesAsync();
        return _mapper.Map(entity);
    }
}

URF with WPF MVVM Caliburn Micro

Answers (1)

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