Question

我有三个项目：

App.Models：包含对象接口。
App.WebAPIService：使用JSON的RESTFul API服务。
App.Client：与RESTful API服务通信的WPF应用程序。

我使用 Entity Framework 来创建接口和模型。

App.Models在其他两个项目中用于创建对象。

public interface ISheet
{
    int ID { get; set; }
    string Name { get; set; }
    Nullable<System.DateTime> CreatedDate { get; set; }
    string CreatedUser { get; set; }

    ICollection<ICategory> Category { get; set; }
}

public interface ICategory
{
    int ID { get; set; }
    string Name { get; set; }
}

App.WebAPIService：

[DataContract(IsReference = true)]
[KnownType(typeof(Category))]
public partial class Sheet : ISheet
{
    #region Primitive Properties
    [DataMember]
    public int ID
    {
        get;
        set;
    }
    [DataMember]
    public Nullable<System.DateTime> CreatedDate
    {
        get;
        set;
    }
    [DataMember]
    public string CreatedUser
    {
        get;
        set;
    }
    [DataMember]
    public string Name
    {
        get;
        set;
    }
    #endregion
    #region Navigation Properties
    [DataMember]
    public ICollection<ICategory> Category
    {
        get
        {
            if (_category == null)
            {
                var newCollection = new FixupCollection<ICategory>();
                newCollection.CollectionChanged += FixupCategory;
                _category = newCollection;
            }
            return _category;
        }
        set
        {
            if (!ReferenceEquals(_category, value))
            {
                var previousValue = _category as FixupCollection<ICategory>;
                if (previousValue != null)
                {
                    previousValue.CollectionChanged -= FixupCategory;
                }
                _category = value;
                var newValue = value as FixupCollection<ICategory>;
                if (newValue != null)
                {
                    newValue.CollectionChanged += FixupCategory;
                }
            }
        }
    }
    private ICollection<ICategory> _category;

    #endregion
    #region Association Fixup
    private void FixupCategory(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (e.NewItems != null)
        {
            foreach (ICategory item in e.NewItems)
            {
                if (!item.Sheet.Contains(this))
                {
                    item.Sheet.Add(this);
                }
            }
        }

        if (e.OldItems != null)
        {
            foreach (ICategory item in e.OldItems)
            {
                if (item.Sheet.Contains(this))
                {
                    item.Sheet.Remove(this);
                }
            }
        }
    }

    #endregion
}

public class SheetController : ApiController
{
    private TORDBEntities db = new TORDBEntities();

    /// <summary>
    /// GET api/Sheet/5
    /// </summary>
    /// <param name="id">int</param>
    /// <returns>Sheet</returns>
    public Sheet GetSheet(int id)
    {
        Sheet sheet = db.Sheet.Include("Category").Single(s => s.ID == id);
        if (sheet == null)
        {
            throw new HttpResponseException
                (Request.CreateResponse(HttpStatusCode.NotFound));
        }

        return sheet;
    }
}

App.Client：

public class Sheet : ISheet
{
    public int ID { get; set; }
    public DateTime? CreatedDate { get; set; }
    public string CreatedUser { get; set; }
    public string Name { get; set; }

    public ICollection<ICategory> Category { get; set; }
}

class ServiceSheet
{
    public Sheet sheet = new Sheet();

    public Sheet GetSheet(int id)
    {
        string url = ConfigurationManager.AppSettings["UrlWebService"];
        url += @"api/sheet/" + id;
        HttpWebRequest requete = WebRequest.Create(url) as HttpWebRequest;
        requete.Method = WebRequestMethods.Http.Get;

        requete.BeginGetResponse(new AsyncCallback(this.GetSheetResponseCallback), 
            requete);

        return sheet;
    }

    private void GetSheetResponseCallback(IAsyncResult ar)
    {
        //Récupération de l'objet HttpWebRequest 
        HttpWebRequest requete = (HttpWebRequest)ar.AsyncState;

        try
        {
            using (HttpWebResponse reponse = requete.EndGetResponse(ar) 
                as HttpWebResponse)
            {
                using (StreamReader streamReader = new
                    StreamReader(reponse.GetResponseStream()))
                {
                    string Text = streamReader.ReadToEnd();
                    sheet = JsonConvert.DeserializeObject<Sheet>(Text);
                    //Newtonsoft.Json.JsonSerializer serializer = new 
                        Newtonsoft.Json.JsonSerializer();
                    //serializer.Converters.Add(new DTOJsonConverter());
                    //Sheet maSheet = serializer.Deserialize(streamReader);
                } 
            }
        }
        catch (WebException we)
        {
            if (we.Status == WebExceptionStatus.ProtocolError)
            {
                HttpWebResponse r = (HttpWebResponse)we.Response;
                if (r.StatusCode == HttpStatusCode.NotFound)

                    MessageBox.Show("Code d'erreur: " + r.StatusCode.ToString());
                r.Close();
            }
            else
                MessageBox.Show(we.Message + " " + we.Status.ToString());
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Erreur");
        }
    }
}

我的反序列化类别出错了。我尝试过以下方法：

public class Sheet : ISheet
{
    public int ID { get; set; }
    public DateTime? CreatedDate { get; set; }
    public string CreatedUser { get; set; }
    public string Name { get; set; }

    [JsonConverter(typeof(ConcreteTypeConverter<Category>))]
    public ICollection<ICategory> Category { get; set; }
}
public class ConcreteTypeConverter<TConcrete> : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        //assume we can convert to anything for now
        return true;
    }

    public override object ReadJson(JsonReader reader, Type objectType, 
        object existingValue, JsonSerializer serializer)
    {
        //explicitly specify the concrete type we want to create
        return serializer.Deserialize<TConcrete>(reader);
    }

    public override void WriteJson(JsonWriter writer, object value, 
        JsonSerializer serializer)
    {
        //use the default serialization - it works fine
        serializer.Serialize(writer, value);
    }
}

错误：

无法转换类型＆＃39; System.Collections.Generic.List 1[App.Client.Models.Category]' to type 'System.Collections.Generic.ICollection 1 [App.Models.ICategory]＆＃39;。
的对象

而且：

public override object ReadJson(JsonReader reader, Type objectType, 
    object existingValue, JsonSerializer serializer)
    {
        //explicitly specify the concrete type we want to create
        List<TConcrete> liste = serializer.Deserialize<List<TConcrete>>(reader);
        ICollection<TConcrete> coll = new Collection<TConcrete>();
        liste.ForEach(delegate(TConcrete obj)
        {
            coll.Add(obj);
        });

        return coll;
    }

错误：

无法投射类型的对象＆＃39; {System.Collections.Generic.Collection {1}} 1 [App.Models.ICategory]＆＃39;

我认为问题只是1[App.Client.Models.Category]' to type 'System.Collections.Generic.ICollection;你有没有遇到过这个问题，或者你有更好的解决方案吗？

答案：

好的，这是我的错！

我忘了添加代码客户端的这一部分：

ICollection

没有FixupCategory，它就无法工作。

希望，这会对一些人有所帮助。感谢那些帮助过我的人。

在C＃中将JSON列表反序列化为ICollection时出错

0 个答案: