传递给WebAPI 2的实体方法正在被插入并链接到现有的实体

本文关键字：实体 插入 链接 WebAPI 方法 | 更新日期: 2023-09-27 18:11:00

我有以下类(简化为简洁);

   public partial class Stock 
{
    [Column("StockId")]
    [JsonProperty(PropertyName = "stockid")]
    public int ID { get; set; }
    public DateTime Date { get; set; }
    public int Quantity { get; set; }
    [JsonProperty(PropertyName = "devicecode")]
    public DeviceTypes Device { get; set; }
}
public partial class DeviceTypes
{
    [Column("id")]
    [JsonProperty(PropertyName = "devicetypeid")]
    public int ID { get; set; }
    public string DeviceType { get; set; }
}

仅用于丰满VS显示表的组成如下;

 CREATE TABLE [dbo].[Stocks] (
    [StockId]     INT            IDENTITY (1, 1) NOT NULL,
    [Date]        DATETIME       NOT NULL,
    [Quantity]    INT            NOT NULL,
    [Device_ID]   INT            NULL,
    CONSTRAINT [PK_dbo.Stocks] PRIMARY KEY CLUSTERED ([StockId] ASC),
    CONSTRAINT [FK_dbo.Stocks_dbo.DeviceTypes_Device_ID] FOREIGN KEY ([Device_ID]) REFERENCES [dbo].[DeviceTypes] ([id])
);
CREATE TABLE [dbo].[DeviceTypes] (
    [id]         INT          IDENTITY (1, 1) NOT NULL,
    [DeviceType] VARCHAR (50) NOT NULL,
    CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED ([id] ASC)
);

现在当我传递例如

Stock objStock = new Stock();
objStock.Device = new DeviceTypes { ID = deviceid };
objStock.Date = DateTime.UtcNow;
objStock.Quantity = quantity;

到API方法，如下所示;

    public IHttpActionResult Post([FromBody]Stock stock)
    {
        //done as a double check 
        var deviceType = _Service.GetDeviceType(stock.Device.ID);
        stock.Device = deviceType;
        _Service.Insert(stock);
        return Ok(stock.ID);
    }

。对象正在击中API post方法，然而，每次它插入一个新的DeviceType而不是链接到有效的一个?

我已经尝试过了，没有从数据库中获得DeviceType，没有快乐。

谁能告诉我我在这里做错了什么?

传递给WebAPI 2的实体方法正在被插入并链接到现有的实体

这是因为EF认为您也在传递一个新的DeviceTypes对象。你可以在stock对象中为这个DeviceTypes对象添加一个标识符，该标识符包含已有DeviceTypes对象的ID:

public partial class Stock 
{
    [Column("StockId")]
    [JsonProperty(PropertyName = "stockid")]
    public int ID { get; set; }
    public DateTime Date { get; set; }
    public int Quantity { get; set; }
    [JsonProperty(PropertyName = "devicecode")]
    public DeviceTypes Device { get; set; }
    [ForeignKey("Device")]
    public int DeviceTypesId {get; set;} // new field, holds existing devicetypes id
}

然后传递stock对象:

Stock objStock = new Stock();
objStock.DeviceTypesId = deviceid;
objStock.Date = DateTime.UtcNow;
objStock.Quantity = quantity;

其中deviceid为数据库中已经存在的DeviceTypes对象的id

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