Question

我有一个WCF服务库和Widnows表单作为客户端。我有数据库ADO.NET EF 我想列出所有尺寸的产品（衣服）。（关系1到很多）。

public partial class ProductsEntity
{
    public ProductsEntity()
    {
        this.Sizes = new HashSet<SizesEntity>();
    }

    public int ID { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }

    public virtual ICollection<SizesEntity> Sizes{ get; set; }
}

这是我的数据合同：

[DataContract]
public class Products
{
    [DataMember]
    public int ID { get; set; }
    [DataMember]
    public string Name{ get; set; }
    [DataMember]
    public decimal Price { get; set; }
    [DataMember]
    public virtual ICollection<SizesEntity> Sizes{ get; set; }

}

 [DataContract]
public class Sizes
{

    [DataMember]
    public int ID { get; set; }
    [DataMember]
    public int Name { get; set; }
    [DataMember]
    public Nullable<int> Quantity { get; set; }
    [DataMember]
    public int ID_Product { get; set; }

    [DataMember]
    public virtual ProductsEntity Products { get; set; }

}

我在数据库中没有这个，但我为我的查询添加了Products_with_sizes（我不确定它是处理它的好方法）

[DataContract]
public class Products_with_sizes
{
    [DataMember]
    public int ID { get; set; }
    [DataMember]
    public string Name { get; set; }
    [DataMember]
    public decimal Price { get; set; }
    [DataMember]
    public int S { get; set; }
    [DataMember]
    public int M { get; set; }
    [DataMember]
    public int L { get; set; }
}

using (var context = new dbMagazynierEntities())
            {
                var q = (from p in context.Products
                            where p.Name.Contains(name) && p.Price>= Price_from && p.Price <= Price_to
                            join r in context.Sizes
                                on p.ID equals r.Prodcuts.ID
                                into sizes
                            select new
                            {
                                ID = p.ID,
                                Name= p.Name,
                                Price = p.Price,
                                S = sizes.Where(x => x.Name== 0).Sum(x => x.Quantity) ?? 0,
                                M = sizes.Where(x => x.Name== 1).Sum(x => x.Quantity) ?? 0,
                                L = sizes.Where(x => x.Name== 2).Sum(x => x.Quantity) ?? 0,
                            });
                odp = new List<Products_with_sizes>();
                foreach (var item in q)
                {
                    odp.Add(new Products_with_sizes{ ID = item.ID, Name= item.Name, Price = item.Price, S = item.S, M = item.M, L = item.L });
                }

所以知道我在我的客户端使用这个方法，我得到错误

                         wyn = context.SzukajProduktu(id, name.Text, price_from, price_to);

我得到：

Cannot implicitly convert type 'System.Collections.Generic.List<Magazynier2WindowsFormsApplication.ServiceReference1.MyServiceProducts_with_sizes>' to 'System.Collections.Generic.List<Magazynier2ServiceLibrary.MyService.Products_with_sizes>'

Answer 1

通过查看您的例外情况，您似乎正在尝试直接将服务代理生成的类投射到您自己创建的DTO中。

即使这两个类具有相同的名称和属性，它们实际上是不同的（即没有共同的父或接口），并且位于不同的名称空间中。

你应该编写一个方法，将代理生成的类明确地转换为你的DTO类，例如。

List<Magazynier2ServiceLibrary.MyService.Products_with_sizes> TranslateProxyClassToDTO(List<Magazynier2WindowsFormsApplication.ServiceReference1.MyServiceProducts_with_sizes> input)
{
    // translate all items and their properties and return the translated list
}

Answer 2

public List<Prodcuts_with_sizes> SzukajProduktu(int id, string name, decimal price_from, decimal price_to)
    {
        List<Prodcuts_with_sizes> odp;
        if (id == -1) //when id is not given
        {
            using (var context = new dbMagazynierEntities())
            {
                var q = (from p in context.Products
                            where p.Name.Contains(name) && p.Price >= price_from && p.Price <= price_to
                            join r in context.Size
                                on p.ID equals r.Products.ID
                                into sizes
                            select new
                            {
                                ID = p.ID,
                                Name = p.Name,
                                Price = p.Price,
                                S = sizes.Where(x => x.Name == 0).Sum(x => x.Quantity) ?? 0,
                                M = sizes.Where(x => x.Name == 1).Sum(x => x.Quantity) ?? 0,
                                L = sizes.Where(x => x.Name == 2).Sum(x => x.Quantity) ?? 0,
                            });
                odp = new List<Prodcuts_with_sizes>();
                foreach (var item in q)
                {
                    odp.Add(new Prodcuts_with_sizes { ID = item.ID, Name = item.Name, Price = item.Price, S = item.S, M = item.M, L = item.L });
                }
                //dataGridView1.DataSource = q.ToList();
            }
            return odp;
        }
        else //when id is given
        {
            using (var context = new dbMagazynierEntities())
            {
                var q = (from p in context.Products
                            where p.ID == id
                            join r in context.Sizes
                                on p.ID equals r.Products.ID
                                into sizes
                            select new
                            {
                                ID = p.ID,
                                Name = p.Name,
                                Price = p.Price,
                                S = sizes.Where(x => x.Name == 0).Sum(x => x.Quantity) ?? 0,
                                M = sizes.Where(x => x.Name == 1).Sum(x => x.Quantity) ?? 0,
                                L = sizes.Where(x => x.Name == 2).Sum(x => x.Quantity) ?? 0,
                            });
                odp = new List<Prodcuts_with_sizes>();
                foreach (var item in q)
                {
                    odp.Add(new Prodcuts_with_sizes { ID = item.ID, Name = item.Name, Price = item.Price, S = item.S, M = item.M, L = item.L });
                }
            }
            return odp;

        }
    }


 using (var context = new MyInterfaceClient())
                {
                     wyn = context.SzukajProduktu(id, name.Text, price_from, price_to);
                    //return wyn;
                }

Answer 3

我通过更改

解决了这个问题

    [OperationContract]
    List<WCFLIB.MyService.Products_with_sizes> SzukajProduktu(int id, string name, decimal price_form, decimal price_to);

到

[OperationContract]
    List<MyService.Products_with_sizes> SzukajProduktu(int id, string name, decimal price_form, decimal price_to);

WCF从WCF服务获取实体

3 个答案: