Table Valued Function and Entity Framework

Question

I\'m trying to execute an TVF with Entity Framework and for some reason it just doesn\'t work. Maybe anyone out there can help me see the problem.

Here are the code samp

Answer 1

Here is a very good article on the newer features of Entity Framework that provide direct support for Table Valued UDFs. MSDN blog on Table-Valued Function Support in Entity Framework.

For greater depth, this article provides significant detail. EDM and store functions exposed in LINQ.

One of the great advantages of the recent support for Table-Valued UDFs involves support for Full-Text Search capabilities. Read more about that here: Full text search features involving database objects.

Answer 2

[Tested] using:

Install-Package EntityFramework.CodeFirstStoreFunctions

Declare a class for output result:

public class MyCustomObject
{
   [Key]
   public int Id { get; set; }
   public int Rank { get; set; }
}

Create a method in your DbContext class

[DbFunction("MyContextType", "SearchSomething")]
public virtual IQueryable<MyCustomObject> SearchSomething(string keywords)
{
   var keywordsParam = new ObjectParameter("keywords", typeof(string)) 
                           { 
                              Value = keywords 
                            };
    return (this as IObjectContextAdapter).ObjectContext
    .CreateQuery<MyCustomObject>(
     "MyContextType.SearchSomething(@keywords)", keywordsParam);
}

Add

public DbSet<MyCustomObject> SearchResults { get; set; }

to your DbContext class

Add in the overriden OnModelCreating method:

modelBuilder.Conventions
.Add(new CodeFirstStoreFunctions.FunctionsConvention<MyContextType>("dbo"));

And now you can call/join with a table values function like this:

CREATE FUNCTION SearchSomething
(   
    @keywords nvarchar(4000)
)
RETURNS TABLE 
AS
RETURN 
(SELECT KEY_TBL.RANK AS Rank, Id
FROM MyTable 
LEFT JOIN freetexttable(MyTable , ([MyColumn1],[MyColumn2]), @keywords) AS KEY_TBL      
ON MyTable.Id = KEY_TBL.[KEY]  
WHERE KEY_TBL.RANK > 0   
)
GO

Answer 3

This is a way to send table parameter to function and return values of table valued function.

C#:

var fooDataTable = new DataTable();
var ids = new List<FooDto>();
if (ids.Count > 0)
{
    fooDataTable.Columns.Add("ID", typeof(int));
    fooDataTable.Columns.Add("CarNumber");
    fooDataTable.Columns.Add("ArriveDate", typeof(DateTime));                

    foreach (var car in ids)
    {
        fooDataTable.Rows.Add(car?.ID, car?.CarNumber, car?.ArriveDate);
    }
}

SqlParameter cdIDs = new SqlParameter("@ListToCalc", SqlDbType.Structured);
cdIDs.Value = fooDataTable;
cdIDs.TypeName = "tp_CarList";

var template = new CarFieldsDTO
{
    Fields = db.Database.SqlQuery<fn_Car_Result>
        ("SELECT * FROM dbo.fn_Car(@ListToCalc)", cdIDs)
            .Select(field => new CarFieldsDTO
            {
                ID = field.ID,
                CarNumber = field.CarNumber,
                ArriveDate = field.ArriveDate,                    
            }).ToList()
};

var fields = new List<CarFieldsDTO> { template };
return fields.AsQueryable();

Where db is DbContext.

DTO:

public class CarFieldsDTO
{        
    public int ID { get; set; }

    public string CarNumber { get; set; }

    public DateTime? ArriveDate { get; set; }

    public IEnumerable<CarFieldsDTO> Fields { get; set; }
}

SQL table valued function:

ALTER  FUNCTION [dbo].[fn_Car]
(
      @ListToCalc tp_CarList READONLY
)
RETURNS TABLE
AS
    RETURN
    (
        SELECT l.ID
               , l.CarNumber
               , l.ArriveDate
        FROM @ListToCalc l
        INNER JOIN Stations as sf ON sf.ID = l.id_StationFrom
    )

User defined Table Type:

CREATE TYPE [dbo].[tp_CarList] AS TABLE(
    [ID] [int] NOT NULL,
    [CarNumber] [varchar](12) NULL,
    [ArriveDate] [datetime] NULL    
)
GO