用于实体框架和 ASP.NET MVC 应用程序的自定义 Linq 查询

Question

I have been working on an ASP.NET MVC app using Entity Framework. Also, it's my first time developing an ASP.NET MVC app. I have been struggling (close to a month of trying and googling) to write a linq query to display results in jQuery datatable for the below SQL query. It involves various left joins and some columns have null values. It would be great if someone could help me out on this. There are 3 tables as below

1. Assets
2. Category
3. Term

SELECT 
    Asset.Name AS Name,
    Asset.Type AS Type,
    Asset.Parent_Asset AS "Parent Asset",
    Cat.Category AS Category,
    Cat.Parent_Category AS "Parent Category",
    T.BUSINESS_TERM AS "Business Term",
    T.SHORT_DESCRIPTION AS Description
FROM 
    (SELECT 
         CH.DISPLAY AS Name,
         CH.TYPE AS Type,
         PA.DISPLAY AS Parent_Asset,
         CH.CATEGORY_INT_ID
     FROM 
         [Metadata].[dbo].[Asset] CH
     LEFT JOIN 
         [Metadata].[dbo].[Asset] PA ON PA.PARENT_ASSET_ID = CH.ASSET_INT_ID) Asset
     LEFT JOIN 
         (SELECT
              CH.DISPLAY AS Category,
              PA.DISPLAY AS Parent_Category,
              CH.CATEGORY_INT_ID AS Category_Id
          FROM 
              [METADATA].[dbo].[Category] CH
          LEFT JOIN 
              [METADATA].[dbo].[Category] PA ON PA.PARENT_CATEGORY_ID = CH.CATEGORY_INT_ID) Cat ON Asset.CATEGORY_INT_ID = Cat.Category_Id
     LEFT JOIN 
         [Metadata].[dbo].[Term] T ON T.CATEGORY_INT_ID = Cat.Category_Id

Answer 1

Create Stored Procedure in the database where the application is connected

CREATE PROCEDURE sp_GetAsset
AS
BEGIN

SELECT 
    Asset.Name AS Name,
    Asset.Type AS Type,
    Asset.Parent_Asset AS ParentAsset,
    Cat.Category AS Category,
    Cat.Parent_Category AS ParentCategory,
    T.BUSINESS_TERM AS BusinessTerm,
    T.SHORT_DESCRIPTION AS Description
FROM 
(
    SELECT 
        CH.DISPLAY AS Name,
        CH.TYPE AS Type,
        PA.DISPLAY AS Parent_Asset,
        CH.CATEGORY_INT_ID
    FROM 
        [Metadata].[dbo].[Asset] CH
    LEFT JOIN 
        [Metadata].[dbo].[Asset] PA ON PA.PARENT_ASSET_ID = CH.ASSET_INT_ID) Asset
    LEFT JOIN 
        (SELECT
             CH.DISPLAY AS Category,
             PA.DISPLAY AS Parent_Category,
             CH.CATEGORY_INT_ID AS Category_Id
         FROM 
             [METADATA].[dbo].[Category] CH
         LEFT JOIN 
             [METADATA].[dbo].[Category] PA ON PA.PARENT_CATEGORY_ID = CH.CATEGORY_INT_ID) Cat ON Asset.CATEGORY_INT_ID = Cat.Category_Id
    LEFT JOIN 
        [Metadata].[dbo].[Term] T ON T.CATEGORY_INT_ID = Cat.Category_Id
);  
END

Create class to get data:

public class TestAsset
{
        public string Name           { get; set; }
        public string Type           { get; set; }
        public string ParentAsset    { get; set; }
        public string Category       { get; set; }
        public string ParentCategory { get; set; }
        public string BusinessTerm   { get; set; }
        public string Description    { get; set; }
}

Get data in your Context

 public class YourContext : DbContext
 {
    public List<TestAsset> GetAssets()
    {
        return this.Query<TestAsset>.FromSql("Exec sp_GetAsset").ToList();
    }
 }

Use GetAssets Method

using (YourContext context = new YourContext())
{       
   var list = context.GetAssets();
}