c# - 为什么我不能使用我的 IService 中的数据合同？

Question

我的 IService 中定义了以下数据协定：

[DataContract]
public class PumpClass {
    [DataMember]
    public int ID { get; set; }
    [DataMember]
    public double litresPumped { get; set; }
    [DataMember]
    public double price { get; set; }
    [DataMember]
    public string fuelType { get; set; }
    [DataMember]
    public DateTime date { get; set; }
    [DataMember]
    public bool requestUse { get; set; }
    [DataMember]
    public bool requestAccepted { get; set; }
    [DataMember]
    public bool finished { get; set; }
}

[DataContract]
public class DieselTank {
    [DataMember]
    public double MaximumLevel { get; set; }
    [DataMember]
    public double WarningLevel { get; set; }
    [DataMember]
    public double CurrentLevel { get; set; }
    [DataMember]
    public bool OrderFuel { get; set; }
}

[DataContract]
public class UnleadedTank {
    [DataMember]
    public double MaximumLevel { get; set; }
    [DataMember]
    public double WarningLevel { get; set; }
    [DataMember]
    public double CurrentLevel { get; set; }
    [DataMember]
    public bool OrderFuel { get; set; }
}

[DataContract]
public class CostOfFuel {
    [DataMember]
    public double DieselSupplierPrice { get; set; }
    [DataMember]
    public double DieselPrice { get; set; }
    [DataMember]
    public double UnleadedSupplierPrice { get; set; }
    [DataMember]
    public double UnleadedPrice { get; set; }
}

[DataContract]
public class Sale {
    [DataMember]
    public double value { get; set; }
    [DataMember]
    public double volumeSold { get; set; }
    [DataMember]
    public DateTime dateSold { get; set; }
}

[DataContract]
public class Ordered {
    [DataMember]
    public double volume { get; set; }
    [DataMember]
    public double cost { get; set; }
}

但只有PumpClass,DieselTank并且UnleadedTank可以从我使用此接口的服务中看到，我不知道为什么。只有这 3 个出现在 Visual Studio 的数据源中。