如何使用Dapper获取存储过程的返回值？

Question

我在使用sql server 2016 express的asp.net mvc 4项目.net f/w 4.6.1中使用Dapper

<packages>
  <package id="Dapper" version="1.50.2" targetFramework="net461" />
</packages> 

我有一个存储过程从两个表中删除应该是事务性的

ALTER PROCEDURE [dbo].[FeedbackDelete] @FeedbackID UNIQUEIDENTIFIER
AS 
    SET NOCOUNT OFF 
    SET XACT_ABORT ON  

BEGIN TRANSACTION
    DELETE
    FROM dbo.Document
    WHERE FeedbackId = @FeedbackID
    IF(@@ERROR != 0)
        BEGIN
            ROLLBACK TRANSACTION
            RETURN 1
        END

    DELETE
    FROM   [dbo].[Feedback]
    WHERE  [FeedbackID] = @FeedbackID
    IF(@@ERROR != 0 OR @@ROWCOUNT != 1)
        BEGIN
            ROLLBACK TRANSACTION
            RETURN 1
        END

COMMIT TRANSACTION
RETURN 0

我的repo方法使用这样的短小精悍

public Response DeleteFeedback(Guid feedbackId)
        {
            string storedProcName = "FeedbackDelete";
            int returnValue = int.MinValue;
            using (var con = Connection)
            {
                con.Open();
                returnValue = con.Execute(storedProcName, new { feedbackId }, commandType: CommandType.StoredProcedure);
            }
            return Convert.ToInt32(returnValue) == 0 ? new Response(Code.Success, "Feedback successfully deleted") : new Response(Code.Failure, "There was an error deleting feedback");
        }

我得到的returnValue每次都是1,这是可以理解的,因为dapper返回受影响的行数.

但是我想得到我的存储过程的return语句的值,以检查事务删除期间的错误(在我的情况下,成功为0,任何错误为1)

我该如何实现这一目标？

使用裸机ado.net我曾经这样做并且它有效

var returnValue = db.ExecuteScalar(storedProcName, new object[] { feedbackId });

使用dapper我尝试了con.ExecuteScalar,因为dapper元数据显示标量//返回://选择的第一个单元格不起作用

任何帮助将不胜感激？

这是我需要使用Dapper执行的下一个过程

ALTER PROCEDURE [dbo].[FeedbackUpdate] 
    @DocumentData VARBINARY(MAX),
    @DocumentName NVARCHAR(100),
    @FeedbackID UNIQUEIDENTIFIER,
    @FirstName NVARCHAR(100),
    @LastName NVARCHAR(100),
    @Notes NVARCHAR(MAX)
AS 
    SET NOCOUNT ON 
    SET XACT_ABORT ON  

    BEGIN TRAN

    UPDATE [dbo].[Feedback]
    SET    [FirstName] = @FirstName, [LastName] = @LastName, [Notes] = @Notes
    WHERE  [FeedbackID] = @FeedbackID
    IF(@@ERROR != 0 OR @@ROWCOUNT != 1)
        BEGIN
            ROLLBACK TRAN
            RETURN 1
        END

    IF DATALENGTH(@DocumentData) > 1
    BEGIN

            DELETE
            FROM   [dbo].[Document]
            WHERE  FeedbackId = @FeedbackId
            IF(@@ERROR != 0)
                BEGIN
                    ROLLBACK TRAN
                    RETURN 1
                END

            INSERT [dbo].[Document] (DocumentData,DocumentName,DocumentId,FeedbackId)
            VALUES(@DocumentData,@DocumentName,NEWID(),@FeedbackID)
            IF(@@ERROR != 0 OR @@ROWCOUNT != 1)
                BEGIN
                    ROLLBACK TRAN
                    RETURN 1
                END
        END

        COMMIT TRAN
        RETURN 0

Answer 1

您可以使用direction声明动态参数:ReturnValue您也可以使用"select"而不是"return"并使用Query<T>扩展名.

create procedure sp_foo
    as
    begin
        return 99
    end

[Test]
public void TestStoredProcedure()
{
    using (var conn = new SqlConnection(@"Data Source=.\sqlexpress;Integrated Security=true; Initial Catalog=foo"))
    {
        var p = new DynamicParameters();
        p.Add("@foo", dbType: DbType.Int32, direction: ParameterDirection.ReturnValue);

        conn.Execute("sp_foo", p, commandType: CommandType.StoredProcedure);

        var b = p.Get<int>("@foo");

        Assert.That(b, Is.EqualTo(99));
    }
}