Question

以下是我要做的事情。我正在使用Entity Framework 6，我有一个DataLayer对象，我将这些层传递给BusinessData对象。基本上从数据库中获取对象并将其值传递给在BusinessData层中镜像它的新对象。

请参阅下面的代码。

实体框架生成的对象

public partial class SolutionArea
    {
        public SolutionArea()
        {
            this.Awards = new HashSet<Award>();
            this.Competencies = new HashSet<Competency>();
            this.KeyWins = new HashSet<KeyWin>();
            this.Offerings = new HashSet<Offering>();
            this.Products = new HashSet<Product>();
            this.Programs = new HashSet<Program>();
        }

        public int ID { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public string Manager { get; set; }
        public string PreSalesCount { get; set; }

        public virtual ICollection<Award> Awards { get; set; }
        public virtual ICollection<Competency> Competencies { get; set; }
        public virtual ICollection<KeyWin> KeyWins { get; set; }
        public virtual ICollection<Offering> Offerings { get; set; }
        public virtual ICollection<Product> Products { get; set; }
        public virtual ICollection<Program> Programs { get; set; }
    }

数据层对象

namespace SolutionsEntities.DataAccessObjects
{
    public class SolutionAreaDAO
    {
        public SolutionAreaBDO GetSolutionArea(int Id)
        {
            SolutionAreaBDO solutionAreaBDO = null;
            using(var context = new SolutionsEntities())
            {
                SolutionArea solutionAreaDAO = (from s in context.SolutionAreas
                                            where s.ID == Id
                                            select s).FirstOrDefault();
                if (solutionAreaDAO != null)
                {
                    solutionAreaBDO = new SolutionAreaBDO();
                    {
                        solutionAreaBDO.Title = solutionAreaDAO.Title;
                        solutionAreaBDO.Programs = solutionAreaDAO.Programs;  
                    }
                }

            }
        }
    }

业务数据对象

    namespace SolutionsBDO
{
    public class SolutionAreaBDO
    {
        public int ID { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public string Manager { get; set; }
        public string PreSalesCount { get; set; }
        public virtual ICollection<AwardBDO> Awards { get; set; }
        public virtual ICollection<CompetencyBDO> Competencies { get; set; }
        public virtual ICollection<KeyWinBDO> KeyWins { get; set; }
        public virtual ICollection<OfferingBDO> Offerings { get; set; }
        public virtual ICollection<ProductBDO> Products { get; set; }
        public virtual ICollection<ProgramBDO> Programs { get; set; }

    }
}

我遇到的问题是在上面的SolutionAreaDAO类中我得到一个错误，说我无法将ICollection转换为ICollection。这是导致问题的代码行：

solutionAreaBDO = new SolutionAreaBDO();
                        {
                            solutionAreaBDO.Title = solutionAreaDAO.Title;
                            solutionAreaBDO.Programs = solutionAreaDAO.Programs;  
                        }

两个对象都具有属于单独实体的属性。 SolutionArea对象包含Program对象的Collection。当我尝试将集合从数据对象设置为业务对象时，我得到一个显式的强制转换错误。

Error      1              Cannot implicitly convert type 'System.Collections.Generic.ICollection<SolutionsEntities.Program>' to 'System.Collections.Generic.ICollection<SolutionsBDO.ProgramBDO>'. An explicit conversion exists (are you missing a cast?) C:\Projects\SolutionsBackgrounder\SolutionsEntities\DataAccessObjects\SolutionAreaDAO.cs 26                52           SolutionsEntities

我确定我没有做对，但如果有人能指出我正确的方向，我将不胜感激！

谢谢，

乔

Answer 1

您正在尝试将ICollection<SolutionsEntities.Program>>转换为ICollection<SolutionsBDO.ProgramBDO>

这是两个具有不同类型参数的集合（就编译器而言，它们是无关的）。您需要手动转换这些对象，更改BDO或DAO上的集合类型，或使用AutoMapper之类的东西自动转换它们

使用Entity Framework ntier - 将列表转换为icollection错误

1 个答案: