实体框架与Codefirst,通用存储库,工作单元模式保存多对多关系

Question

我在使用EF Codefirst正确保存多对多关系时遇到问题.我已正确建模我的类并使用Fluent-API正确建模连接表.我认为这个问题与使用断开连接的DTO有关.当我将更改保存到父实体(公寓)时,父实体(例如Title和UserId)上的scalular属性保存正确,但对子实体(设施)的更改不会保存到多对多表.

这是有助于澄清事物的代码流:

public ICommandResult Execute(CreateOrUpdateCondoCommand command)
    {
        ICollection<Amenity> amenities = new List<Amenity>();

        foreach (var item in command.Amenities)
        {
            Amenity amenity = new Amenity { AmenityId = item.AmenityId };
            amenities.Add(amenity);
        }

        var condo = new Condo
        {
            [...other properties]
            Title = command.Title,               
            Amenities = amenities             
        };                  

        if (condo.CondoId == 0)
        {
            condoRepository.Add(condo);
        }
        else
        {
            condoRepository.Update(condo);
        }

        unitOfWork.Commit();

        return new CommandResult(true);
    }

    /// <summary>
    /// Updates the entity.
    /// </summary>
    /// <param name="entity">The entity</param>
    public virtual void Update(T entity)
    {
        dbset.Attach(entity);
        dataContext.Entry(entity).State = EntityState.Modified;
    }

我能够通过创建condoRepository.UpdateCondo(condo)方法来完成工作,如下所示:

/// <summary>
    /// Method for updating a condo
    /// </summary>   
    /// <param name="condo">The condo to update</param>
    public void UpdateCondo(Condo condo)
    { 
        var updatedCondo = this.DataContext.Set<Condo>().Include("Amenities")
            .Single(x => x.CondoId == condo.CondoId);

        // Set the attributes
        [other properties here...]
        updatedCondo.Title = condo.Title;           

        updatedCondo.Amenities.Clear();

        foreach (var amenity in condo.Amenities)
        {
            var amenityToAttach = this.DataContext.Amenities.Single(x => x.AmenityId == amenity.AmenityId);
            updatedCondo.Amenities.Add(amenityToAttach);                
        }

        this.Update(updatedCondo);
    }

但是,是否有更好的方法来执行此操作,这是通用的,并且每次我需要保存多对多关系时不需要我创建自定义"更新"方法？这个/sf/answers/781851521/答案有助于澄清我认为问题所在,但我不确定如何实现更通用的方法.

谢谢你,杰森

Answer 1

尝试使用本教程，希望对您有所帮助。

http://www.asp.net/mvc/tutorials/getting-started-with-ef-5-using-mvc-4/creating-a-more-complex-data-model-for-an-asp-net- mvc 应用程序。