Web API Restful服務ReadAsAsync <type>不返回列表

Question

我試圖返回類的內部對象的列表，但是當我嘗試讀取容器類的結果時，它將列表中的空值刪除。我對Web API非常陌生，所以我不知道這是通過設計還是我做錯了什麼。如果我將響應內容讀入字符串，那麼列表就在那裏。第一張圖片顯示列表完整，第二張顯示他們不再可用。任何方向將不勝感激！

using (HttpClient client = new HttpClient()) 
      { 
       string url = Url(String.Format("{0}", id)); 
       SetupClient(client, url); 

       HttpResponseMessage response = client.GetAsync(url).Result; 

       if (response.IsSuccessStatusCode) 
       { 


        shipment = response.Content.ReadAsAsync<ShipmentViewModel>().Result; 

       } 

編輯添加ShipmentViewModel源

public class ShipmentViewModel 
{ 
    public Guid Id { get; set; } 

    public String ShipmentName { get; set; } 

    public String Description { get; set; } 

    public String Comments { get; set; } 

    /// <summary> 
    /// Used for UI display purposes only 
    /// </summary> 

    public int NumberOrdersScanned { get; set; } 
    public int NumberOrdersTotal { get; set; } 

    public int NumberParcelsScanned { get; set; } 
    public int NumberParcelsTotal { get; set; } 

    public List<ShipmentEntity> ShipmentEntities { get; set; } 

    public ShipmentEntity ShipmentEntity { get; set; } 
    public Guid ValidationTypeId { get; set; } 
    //  public string ValidationType { get; set; } 
    public ValidationType ValidationType { get; set; } 
    public List<ValidationType> ValidationTypes { get; set; } 
    /// <summary> 
    /// Used for UI display purposes only 
    /// </summary> 
    public List<ShipmentStatus> ShipmentStatuses { get; set; } 

    public ShipmentStatus ShipmentStatus { get; set; } 

    /// <summary> 
    /// Used for UI display purposes only 
    /// </summary> 
    public List<ShipmentDestinationCountry> DestinationCountries { get; set; } 

    public ShipmentDestinationCountry DestinationCountry { get; set; } 

    private List<ShipmentTrackingNumber> _TrackingNumbers; 
    public List<ShipmentTrackingNumber> TrackingNumbers 
    { 
     get 
     { 
      return _TrackingNumbers ?? (_TrackingNumbers = new List<ShipmentTrackingNumber>()); 
     } 
     set 
     { 
      _TrackingNumbers = value; 
     } 
    } 

    public bool RequiresValidation { get; set; } 
    private List<ShipmentValidationViewModel> _Validations { get; set; } 

    public List<ShipmentValidationViewModel> Validations 
    { 
     get 
     { 
      return _Validations ?? (_Validations = new List<ShipmentValidationViewModel>()); 
     } 
     set 
     { 
      _Validations = value; 
     } 
    } 

    public Guid EdiShipmentInfoId { get; set; } 
    public EdiShipmentInfoViewModel EdiShipmentInfo { get; set; } 

    public ShipmentEvents Events { get; set; } 
} 

這裏是EdiShipmentInfoViewModel

public class EdiShipmentInfoViewModel 
{ 
    //  private string _packagingCode; 
    public Guid Id { get; set; } 
    public Guid ShipmentId { get; set; } 
    public Guid WarehouseId { get; set; } 
    public virtual InternalLookupModel Warehouse { get; set; } 
    public DateTime? ShippingDate { get; set; } 
    public DateTime? DeliveryDate { get; set; } 
    public string EquipmentNumber { get; set; } 

    public string ShippingWeight { get; set; } 

    public string PackagingCode { get; set; } 

    public string CarrierCommonName { get; set; } 
    public Guid ScacCodeId { get; set; } 
    public virtual InternalLookupModel ScacCode { get; set; } 
    public Guid PackagingFormId { get; set; } 
    public virtual InternalLookupModel PackagingForm { get; set; } 
    public Guid PackagingMaterialId { get; set; } 
    public virtual InternalLookupModel PackagingMaterial { get; set; } 

    public string MasterBillLading { get; set; } 
    public string BillLading { get; set; } 
    public string LadingDescription { get; set; } 
    public string FobShippingPoint { get; set; } 
    public string FobDestination { get; set; } 
    public Guid TransPayMethodId { get; set; } 
    public virtual InternalLookupModel TransPayMethod { get; set; } 
    public Guid TransTypeId { get; set; } 
    public virtual InternalLookupModel TransType { get; set; } 
    public Guid ServiceLevelCodeId { get; set; } 
    public virtual InternalLookupModel ServiceLevelCode { get; set; } 
    public Guid UnitOfMeasureId { get; set; } 
    public virtual InternalLookupModel UnitOfMeasure { get; set; } 


    private List<InternalLookupModel> _WarehouseList; 
    public List<InternalLookupModel> WarehouseList 
    { 
     get { return _WarehouseList ?? new List<InternalLookupModel>(); } 
     set { this._WarehouseList = value; } 
    } 

    private List<InternalLookupModel> _ScacCodeList; 

    public List<InternalLookupModel> ScacCodeList 
    { 
     get { return _ScacCodeList ?? new List<InternalLookupModel>(); } 
     set { this._ScacCodeList = value; } 
    } 
    private List<InternalLookupModel> _PackagingFormList; 
    public List<InternalLookupModel> PackagingFormList 
    { 
     get { return _PackagingFormList ?? new List<InternalLookupModel>(); } 
     set { this._PackagingFormList = value; } 
    } 

    private List<InternalLookupModel> _PackagingMaterialList; 
    public List<InternalLookupModel> PackagingMaterialList 
    { 
     get { return _PackagingMaterialList ?? new List<InternalLookupModel>(); } 
     set { this._PackagingMaterialList = value; } 
    } 

    private List<InternalLookupModel> _TransPayMethodList; 
    public List<InternalLookupModel> TransPayMethodList 
    { 
     get { return _TransPayMethodList ?? new List<InternalLookupModel>(); } 
     set { this._TransPayMethodList = value; } 
    } 

    private List<InternalLookupModel> _TransTypeList; 
    public List<InternalLookupModel> TransTypeList 
    { 
     get { return _TransTypeList ?? new List<InternalLookupModel>(); } 
     set { this._TransTypeList = value; } 
    } 

    private List<InternalLookupModel> _ServiceLevelCodeList; 

    public List<InternalLookupModel> ServiceLevelCodeList 
    { 
     get { return _ServiceLevelCodeList ?? new List<InternalLookupModel>(); } 
     set { this._ServiceLevelCodeList = value; } 
    } 

    private List<InternalLookupModel> _UnitOfMeasureList; 

    public List<InternalLookupModel> UnitOfMeasureList 
    { 
     get { return _UnitOfMeasureList ?? new List<InternalLookupModel>(); } 
     set { this._UnitOfMeasureList = value; } 
    } 
} 

Answer 1

我覺得@BrianBall是正確的。重寫你的類，以便你的列表屬性是簡單的getter/setter，並在你的構造函數中初始化列表。

public class ShipmentViewModel 
{ 
    public ShipmentViewModel() 
    { 
    TrackingNumbers = new List<ShipmentTrackingNumber>(); 
    } 

    public List<ShipmentTrackingNumber> TrackingNumbers { get; set; } 
    // and so on 
}