EF：从C＃将表值参数传递给用户定义的函数

问题描述

我在sql Server中有一个用户定义的函数，该函数接受TVP（表值参数）作为参数。在EF中，如何从C＃调用这样的函数？

我尝试使用方法ObjectContext.createquery<>，但遇到以下错误：

函数“ QueryByParam”的参数“ param”无效。参数只能是可以转换为Edm标量类型的类型。

也尝试了方法ObjectContext.ExecuteStoreQuery<>，并得到了相同的错误。无论如何，它不会返回IQueryable。

示例代码

[DbFunction(nameof(SampleDbContext),"QueryByParam")]
public IQueryable<SecurityQueryRow> QueryByParam(IEnumerable<ProfileType> profiles,bool isActive = false)
{
    DataTable dataTable = ....
    ObjectParameter profilesParam = new ObjectParameter("profileTypeIds",dataTable);

    ObjectParameter isActiveParam = new ObjectParameter("isActive ",isActive);

    return ((IObjectContextAdapter)this).ObjectContext.createquery<SecurityQueryRow>(
            string.Format("[{0}].[{1}](@profileTypeIds,@isActive)",GetType().Name,"QueryByParam"),profilesParam,isActiveParam);
}

要求是我们需要IQueryable返回，而不是消耗的结果。

解决方法

您可以使用Raw Sql en EF Core（与EF6中的方法类似）来执行此操作，但无法获得IQueryable。下面的两个示例。

实体框架核心

SQL类型以将其用作列表过滤器：

CREATE TYPE [dbo].[Table1Type] AS TABLE(
    [Id] [int] NULL,[Name] [nchar](10) NULL
)

SQL UDF：

CREATE FUNCTION [dbo].[Func1] 
(   
    @Ids Table1Type readonly
)
RETURNS TABLE 
AS
RETURN
(
    SELECT * from Table1 where id in (select Id from @Ids)
)

EF上下文：

public class MyContext : DbContext
{
    public DbSet<Table1> Table1 { get; set; }
}

DTO以匹配sql类型（为简单起见，也与表相同）：

public class Table1
{
    public int Id { get; set; }
    public string Name { get; set; }
}

示例：

static void Main(string[] args)
{
    using (var context = new MyContext())
    {
        // Declare de Structure filter param
        var dt = new DataTable();

        DataTable table = new DataTable();
        table.Columns.Add(new DataColumn("Id",typeof(int)));
        table.Columns.Add(new DataColumn("Name",typeof(string)));
        DataRow row = table.NewRow();
        row["Id"] = 1;
        row["Name"] = "Item";
        table.Rows.Add(row);
        var param = new SqlParameter("@Ids",table) { TypeName = "dbo.Table1Type",SqlDbType = SqlDbType.Structured };

        IQueryable<Table1> query = context.Table1.FromSqlRaw("SELECT * FROM dbo.func1(@Ids)",param);
        var result = query.ToList();
    }
}

实体框架6

您无法获得IQueryable，但是可以对生成的IEnumerable进行限制。

static void Main(string[] args)
{
    using (var context = new MyContext())
    {
        context.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);

        // Declare de Structure filter param
        var dt = new DataTable();

        DataTable table = new DataTable();
        table.Columns.Add(new DataColumn("Id",SqlDbType = SqlDbType.Structured };

        var query = context.Table1.SqlQuery("SELECT * FROM dbo.func1(@Ids)",param);

        var result = query.ToList();
    }
}

,

AdventureWorks示例数据库具有一个表值函数dbo.ufnGetContactInformation，其返回类型也可以表示为另一种复杂类型

[ComplexType]
public class ContactInformation
{
    public int PersonID { get; set; }

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string JobTitle { get; set; }

    public string BusinessEntityType { get; set; }
}

然后可以通过以下方式映射ufnGetContactInformation函数：

// Defines table-valued function,which must return IQueryable<T>.
[Function(FunctionType.TableValuedFunction,nameof(ufnGetContactInformation),Schema = dbo)]
public IQueryable<ContactInformation> ufnGetContactInformation(
    [Parameter(DbType = "int",Name = "PersonID")]int? personId)
{
    ObjectParameter personIdParameter = personId.HasValue
        ? new ObjectParameter("PersonID",personId)
        : new ObjectParameter("PersonID",typeof(int));

    return this.ObjectContext().CreateQuery<ContactInformation>(
        $"[{nameof(this.ufnGetContactInformation)}](@{nameof(personId)})",personIdParameter);
}

它的返回类型应该是IQueryable，以便它在LINQ to Entities中是可组合的。它可以被称为：

[TestMethod]
public void CallTableValuedFunction()
{
    using (AdventureWorks database = new AdventureWorks())
    {
        IQueryable<ContactInformation> employees = database.ufnGetContactInformation(1).Take(2);
        Assert.IsNotNull(employees.Single());
    }
}

上述ufnGetContactInformation调用和Take调用将转换为一个SQL查询：

exec sp_executesql N'SELECT TOP (2) 
    [top].[C1] AS [C1],[top].[PersonID] AS [PersonID],[top].[FirstName] AS [FirstName],[top].[LastName] AS [LastName],[top].[JobTitle] AS [JobTitle],[top].[BusinessEntityType] AS [BusinessEntityType]
    FROM ( SELECT TOP (2) 
        [Extent1].[PersonID] AS [PersonID],[Extent1].[FirstName] AS [FirstName],[Extent1].[LastName] AS [LastName],[Extent1].[JobTitle] AS [JobTitle],[Extent1].[BusinessEntityType] AS [BusinessEntityType],1 AS [C1]
        FROM [dbo].[ufnGetContactInformation](@PersonID) AS [Extent1]
    )  AS [top]',N'@PersonID int',@PersonID=1