问EF:从C#将表值参数传递给用户定义的函数。
EN

Stack Overflow用户

提问于 2020-09-04 06:16:52

回答 2查看 2.6K关注 0票数 13

我在Server中有一个用户定义的函数，它接受一个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ObjectContext.CreateQuery<>方法，但得到了以下错误：

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ObjectContext.ExecuteStoreQuery<>方法，得到了同样的错误。无论如何，它不会返回一个IQueryable。

样本代码

[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);
}

需求是我们需要一个IQueryable返回，而不是消耗的结果。

entity-framework-6

table-valued-parameters

sql-server

entity-framework

回答 2

Stack Overflow用户

发布于 2020-09-07 09:09:14

您可以使用(类似于EF6中的aproach )来实现它，但是您不能获得一个IQueryable。这两个例子都在下面。

实体框架核心

将SQL类型用作列表筛选器：

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 (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，但可以将其链接到生成的IEnumerable。

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", 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 };

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

        var result = query.ToList();
    }
}

票数 9

Stack Overflow用户

发布于 2020-09-09 04:01:18

AdventureWorks示例数据库有一个表值函数dbo.ufnGetContactInformation，它的返回类型也可以表示为另一个复杂类型。

[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，因此它在LINQ实体中是可组合的。它可以称为：

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

上面的ufnGetContactInformation调用和接受调用将被转换为一个单一的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