Linq使用EF無法正常工作的情況

Question

一直在試圖找出我的查詢出了什么問題，並且一直在使用Where條件進行回合，但是沒有運氣。 以下是我在控制器文件中的查詢。

ValueStory valuestory = await db.ValueStories.FindAsync(id);

//Area Of Interest Value Drivers
var aoivaluedriver = (from AOIValueDrivers in db.AOIValueDrivers
                      join aoivd in db.AOIValueDrivers on AOIValueDrivers.AOIVDId equals aoivd.AOIId
                      join aoi in db.AreaOfInterests on aoivd.AOIId equals aoi.AOIId
                      join vs in db.ValueStories on aoi.Id equals vs.Id
                      where aoivd.AOIId == aoi.AOIId && aoi.Id == vs.Id && vs.Id == id
                      select aoivd
                      ).ToList();

List<AOIValueDrivers> aoivd1 = new List<AOIValueDrivers>();
foreach (var a in aoivaluedriver)
{
    aoivd1.Add(new AOIValueDrivers()
    {
        AOIVDId = a.AOIVDId,
        Item = a.Item,
        SubItem = a.SubItem,
        Value = a.Value,
        AOIId = a.AOIId

    });
}
//Area pf Interest  Value Drivers End


//Area Of Interest
var areaOfInterest = (from AreaOfInterest in db.AreaOfInterests
                      join aoi in db.AreaOfInterests on AreaOfInterest.AOIId equals aoi.AOIId
                      join vs in db.ValueStories on aoi.Id equals vs.Id
                      where aoi.Id == vs.Id && vs.Id == id
                      select aoi
                      //{
                      // AOIName = aoe.AOIName,
                      //ValueDriver = aoe.ValueDriver
                      //}
                             ).ToList();

List<AreaOfInterest> aoi1 = new List<AreaOfInterest>();
foreach (var a in areaOfInterest)
{
    aoi1.Add(new AreaOfInterest()
    {
        AOIId = a.AOIId,
        AOIName = a.AOIName,
        Selected = a.Selected,
        Id = a.Id,
        AOIValueDrivers = aoivd1

    });
}

我的Json中的結果是它列出了我的所有aoivaluedriver數據ang都忽略了Where條件。 這是Json的輸出

{
  "AreaOfInterest": [
    {
      "AOIId": 1,
      "AOIName": "Supply Chain/ Direct Materials",
      "Selected": true,
      "Id": 1,
      "ValueStory": null,
      "AOIValueDrivers": [
        {
          "AOIVDId": 1,
          "Item": "Negotiate better prices & conditions",
          "SubItem": "Automate the process of sourcing of direct materials and integrate it to you ERP and key execution systems",
          "Value": 3,
          "AOIId": 1,
          "AreaOfInterest": null
        },
        {
          "AOIVDId": 2,
          "Item": "Lower Cost",
          "SubItem": "Reduct costs of supply chain FTEs",
          "Value": 3,
          "AOIId": 1
        },
        {
          "AOIVDId": 10,
          "Item": "Negotiate better prices & conditions",
          "SubItem": "Foster supplier competition to reduce pricing and obtain best market value",
          "Value": 3,
          "AOIId": 2
        },
        {
          "AOIVDId": 19,
          "Item": "Negotiate better prices & conditions",
          "SubItem": "Control and maximise savings on non strategically source spend",
          "Value": 3,
          "AOIId": 3
        },
        {
          "AOIVDId": 24,
          "Item": "Buy and pay at the negotiated rate & conditions",
          "SubItem": "Reduce invoice matching exceptions (to contracts, orders, & receipts)",
          "Value": 3,
          "AOIId": 4
        },
        {
          "AOIVDId": 34,
          "Item": "Free up working capital",
          "SubItem": "Offer suppliers options to get paid quicker while not reducing DPO",
          "Value": 3,
          "AOIId": 5
        },
        {
          "AOIVDId": 38,
          "Item": "Protect your revenue",
          "SubItem": "Access to systems such as Dun & Bradstreet to certify suppliers",
          "Value": 3,
          "AOIId": 6
        },
        {
          "AOIVDId": 43,
          "Item": "nothing",
          "SubItem": "nothing",
          "Value": 0,
          "AOIId": 7
        }
      ]
    }
  ]
}

預期的結果是它只應返回AOIId = 1的所有項目，而應返回表中的所有項目。 我的查詢可能出什么問題了？ 對於EF和Linq來說仍然很陌生，並且仍在嘗試使自己熟悉它。

這是我感興趣的領域的數據庫建模

CREATE TABLE [dbo].[AreaOfInterest] (
    [AOIId]    INT            IDENTITY (1, 1) NOT NULL,
    [AOIName]  NVARCHAR (MAX) NOT NULL,
    [Selected] BIT            NOT NULL,
    [Id]       INT            NOT NULL,
    CONSTRAINT [PK_dbo.AreaOfInterest] PRIMARY KEY CLUSTERED ([AOIId] ASC),
    CONSTRAINT [FK_dbo.AreaOfInterest_dbo.ValueStory_Id] FOREIGN KEY ([Id]) REFERENCES [dbo].[ValueStory] ([Id]) ON DELETE CASCADE
);

GO
CREATE NONCLUSTERED INDEX [IX_Id]
    ON [dbo].[AreaOfInterest]([Id] ASC);

這是areaofinterestvaluevaluedriver的

CREATE TABLE [dbo].[AOIValueDrivers] (
    [AOIVDId] INT            IDENTITY (1, 1) NOT NULL,
    [Item]    NVARCHAR (MAX) NULL,
    [SubItem] NVARCHAR (MAX) NULL,
    [Value]   INT            NOT NULL,
    [AOIId]   INT            NOT NULL,
    CONSTRAINT [PK_dbo.AOIValueDrivers] PRIMARY KEY CLUSTERED ([AOIVDId] ASC),
    CONSTRAINT [FK_dbo.AOIValueDrivers_dbo.AreaOfInterest_AOIId] FOREIGN KEY ([AOIId]) REFERENCES [dbo].[AreaOfInterest] ([AOIId]) ON DELETE CASCADE
);
GO
CREATE NONCLUSTERED INDEX [IX_AOIId]
    ON [dbo].[AOIValueDrivers]([AOIId] ASC);

預期的json輸出應該像這樣

{
  "AreaOfInterest": [
    {
      "AOIId": 1,
      "AOIName": "Supply Chain/ Direct Materials",
      "Selected": true,
      "Id": 1,
      "ValueStory": null,
      "AOIValueDrivers": [
        {
          "AOIVDId": 1,
          "Item": "Negotiate better prices & conditions",
          "SubItem": "Automate the process of sourcing of direct materials and integrate it to you ERP and key execution systems",
          "Value": 3,
          "AOIId": 1,
          "AreaOfInterest": null
        }
      ]
    }
  ],
   "AreaOfInterest": [
    {
      "AOIId": 2,
      "AOIName": "Supply Chain/ Direct Materials",
      "Selected": true,
      "Id": 1,
      "ValueStory": null,
      "AOIValueDrivers": [
        {
          "AOIVDId": 10,
          "Item": "Negotiate better prices & conditions",
          "SubItem": "Foster supplier competition to reduce pricing and obtain best market value",
          "Value": 3,
          "AOIId": 2
        }
      ]
    }
  ],
    "AreaOfInterest": [
    {
      "AOIId": 3,
      "AOIName": "Supply Chain/ Direct Materials",
      "Selected": true,
      "Id": 1,
      "ValueStory": null,
      "AOIValueDrivers": [
        {
          "AOIVDId": 19,
          "Item": "Negotiate better prices & conditions",
          "SubItem": "Control and maximise savings on non strategically source spend",
          "Value": 3,
          "AOIId": 3
        }
      ]
    }
  ]
}

這是我的模型的樣子：

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;

namespace WebService.Models
{
    public class AreaOfInterest
    {


        [Key]
        public int AOIId { get; set; }
        [Required]
        public string AOIName { get; set; }
        public bool Selected { get; set; }

        // Foreign Key
        public int Id { get; set; }
        // Navigation property
        public virtual ValueStory ValueStory { get; set; }

        //Value Drivers AOI for the Value Story
        public List<AOIValueDrivers> AOIValueDrivers { get; set; }

    }

    public class AOIValueDrivers
    {
        [Key]
        public int AOIVDId { get; set; }
        public string Item { get; set; }
        public string SubItem { get; set; }
        public int Value { get; set; }

        // Foreign Key
        public int AOIId { get; set; }
        // Navigation property
        public virtual AreaOfInterest AreaOfInterest { get; set; }

    }

}

這是工作代碼

      //Area Of Interest Value Drivers
      var aoivaluedriver = (from AOIValueDrivers in db.AOIValueDrivers
                            join aoivd in db.AOIValueDrivers on AOIValueDrivers.AOIVDId equals aoivd.AOIId
                            join aoi in db.AreaOfInterests on aoivd.AOIId equals aoi.AOIId
                            select aoivd
                            ).ToList();

      List<AOIValueDrivers> aoivd1 = new List<AOIValueDrivers>();
      foreach (var a in aoivaluedriver)
      {
          aoivd1.Add(new AOIValueDrivers()
          {
              AOIVDId = a.AOIVDId,
              Item = a.Item,
              SubItem = a.SubItem,
              Value = a.Value,
              AOIId = a.AOIId

          });
      }
    //Area pf Interest  Value Drivers End

    //Area Of Interest
    var areaOfInterest = (from AreaOfInterest in db.AreaOfInterests
                          join aoi in db.AreaOfInterests on AreaOfInterest.AOIId equals aoi.AOIId
                          join vs in db.ValueStories on aoi.Id equals vs.Id
                          where aoi.Id == vs.Id && vs.Id == id
                          select aoi).ToList();



    List<AreaOfInterest> aoi1 = new List<AreaOfInterest>();
    foreach (var a in areaOfInterest)
    {
        aoi1.Add(new AreaOfInterest()
        {
            AOIId = a.AOIId,
            AOIName = a.AOIName,
            Selected = a.Selected,
            Id = a.Id,
            AOIValueDrivers = aoivd1?.Where(vd => vd.AOIId == a.AOIId)?.ToList()

        });
    }
    //Area pf Interest End

Answer 1

讓我們在這里簡化一下。

利用Entity Framework的延遲加載方法和建模，並且我假設您的實體建模是正確的，您可以執行類似的操作（僅作為示例）。

//Area Of Interest
var areaOfInterest = (from AreaOfInterest in db.AreaOfInterests.Include(a => a.AOIValueDrivers)
                      join aoi in db.AreaOfInterests on AreaOfInterest.AOIId equals aoi.AOIId
                      join vs in db.ValueStories on aoi.Id equals vs.Id
                      where aoi.Id == vs.Id && vs.Id == id
                      select aoi).ToList();


List<AreaOfInterest> aoi1 = new List<AreaOfInterest>();
foreach (var a in areaOfInterest)
{
    aoi1.Add(new AreaOfInterest()
    {
        AOIId = a.AOIId,
        AOIName = a.AOIName,
        Selected = a.Selected,
        Id = a.Id,
        AOIValueDrivers = a.AOIValueDrivers.Where(vd => vd.AOIId == a.AOIId).ToList()
    });
}

您不需要執行兩個查詢，因為當您對具有其他相關實體的實體進行選擇時，實體框架會延遲加載該關系。

在此處https://msdn.microsoft.com/zh-cn/library/jj574232(v=vs.113).aspx和此處http://www.entityframeworktutorial.net/EntityFramework4.3/lazy-loading中找到更多相關信息-with-dbcontext.aspx

Answer 2

我不太了解，但是根據代碼，您的linq查詢不正確。 查詢中的where子句錯誤。

如果您希望AOIID == 1的項，則下面的代碼將起作用。

var aoivaluedriver = (from AOIValueDrivers in db.AOIValueDrivers
                  join aoivd in db.AOIValueDrivers on AOIValueDrivers.AOIVDId equals aoivd.AOIId
                  join aoi in db.AreaOfInterests on aoivd.AOIId equals aoi.AOIId
                  join vs in db.ValueStories on aoi.Id equals vs.Id
                  where aoivd.AOIId == 1
                  select aoivd
                  ).ToList();

-加根https://blossomprogramming.blogspot.in/