Linq在條件無法正常工作的情況下，使用EF

一直在試圖弄清楚我的查詢出了什麼問題，並且一直在玩Where條件的一輪，但沒有運氣。以下是我在控制器文件中的查詢。Linq在條件無法正常工作的情況下，使用EF

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 

    }); 
}

在我的Json結果是它列出我所有的aoivaluedriver數據昂忽略我的Where條件。這裏是JSON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，它應該只AOIId = 1，而是其返回的所有表中的項目將返回所有項目。我的查詢有什麼問題？對EF和Linq仍然很陌生，仍然試圖讓自己熟悉它。

這裏是我的areaofinterest

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);

數據庫建模，這裏是一個爲areaofinterestvaluedriver

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輸出應該是這樣的

{ 
    "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 
     } 
     ] 
    } 
    ] 
}

這是怎麼了我的模特看起來：

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; } 

    } 

}

這是工作的代碼

 //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

來源

2017-07-31 Raymund Evangelista

您的查詢是沒有意義的。爲什麼你自己加入'db.AreaOfInterests'，然後將它加入到'db.ValueStories'中，但從不使用值'db.ValueStories'？ – DavidG

你可以發佈你的數據庫建模這些表嗎？我認爲你有一個懶加載問題，因爲你的表關係。 –

@Erick，我已經更新了我的帖子，數據庫結構 –

我們來試試這裏事情簡單化。

利用實體框架延遲加載方法和建模，我假設你實體建模是正確的，你可以做一些事情（只是一個例子）。

//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() 
    }); 
}

你並不需要做兩個查詢，因爲當你做一個選擇上的實體有相關的關係懶由實體框架加載其他實體。

來源

2017-07-31 08:55:58

我試過這個，但我得到一個CS0266錯誤：不能將類型'system.collections.generic.ienumerable '轉換爲'System.collections.generic.list vd.AOIId == a.AOIId） –

將ToList（）放在where的末尾。看我的編輯。 –

早些時候嘗試過，但當我在Postman上運行它時出現此錯誤： [link] https://ibb.co/gsda4k –

我不明白很多，但按代碼的LINQ查詢是不正確的。查詢中where子句是錯誤的。

如果你想AOIID == 1的項目，那麼下面的代碼將工作。

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();

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

來源

2017-07-31 08:46:15

我已經試過了。我通過發佈進行了更新，幷包含了預期的json輸出。 –

Linq在條件無法正常工作的情況下，使用EF

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