如何使用存储过程结果在 ASP.NET MVC 中将列表项作为 JSON 返回？

Question

I want to return some data from a SQL Server table; I used a stored procedure like this:

ALTER PROCEDURE [dbo].[SP_TITILESEARCH]
    (@FLAG INT, 
     @Author VARCHAR(300) = NULL,
     @Category VARCHAR(100) = NULL,
     @Title VARCHAR(MAX) = NUll)
AS
BEGIN
    IF (@FLAG = 1)
    BEGIN
        SELECT * 
        FROM SmartLibClientDB.dbo.LibraryMediaEntry 
        WHERE Title LIKE '%' + @Title + '%' 
    END
END

On the server-side, the stored procedure is executed like this:

var media = new LibraryMediaEntry();
var db = new SchooberrySchoolEntities();

SqlParameter param1 = new SqlParameter("@Title", "Charpy Impact Test");
SqlParameter param2 = new SqlParameter("@FLAG", 1);

media = db.Database.SqlQuery<LibraryMediaEntry>("exec SP_TITILESEARCH @Title, @FLAG", param1, param2)
                   .ToList()
                   .FirstOrDefault();   // Getting error when executed
return Json(media, JsonRequestBehavior.AllowGet);

But the code throws an error:

Conversion failed when converting the varchar value 'Charpy Impact Test' to data type int.

What I want to do is return the table data as JSON is this the correct method to do this? Or why the error? I can't understand what I am doing wrong because the column the error asking to convert to int is actually a varchar column

Note: I am using a stored procedure because the data I am returning is from a different database on the same server

Answer 1

Conversion failed when converting the varchar value 'Charpy Impact Test' to data type int.

This means that the @Title parameter is expecting an int (integer). Charpy Impact Test is not an integer so your stored procedure call fails. Picking an integer value is the first step.

want to do is return the table data as JSON

Your code:

 media = db.Database.SqlQuery<LibraryMediaEntry>("exec SP_TITILESEARCH @Title,@FLAG"
  ,param1
  ,param2)
  .ToList()
  .FirstOrDefault();

is calling .FirstOrDefault() which will result in a singe row in media. Did you intend to have a single record returned?

Answer 2

There are a couple of possible issues with your code.

Your stored proc param @FLAG is defined as varchar(25) . Yet, when populating it, you are passing an integer ( SqlParameter param2 = new SqlParameter("@FLAG",1); ). Change it to:

var param2 = new SqlParameter("@FLAG", "1");

On the matter of the actual error you are getting... Check your LibraryMediaEntry object. Is the property that's getting populated an int by any chance? That's probably where the problem lies.

Finally, your stored proc. SELECT * FROM is bad form in a stored procedure. Specify the actual fields you want. It also helps with debugging.

Answer 3

I couldn't find what caused the error but passing all parameters including the null did the job for me

var DB = new dbEntities();
                    SqlParameter param1 = new SqlParameter("@FLAG", 1);
                    SqlParameter param2 = new SqlParameter("@Author", "");
                    SqlParameter Param3 = new SqlParameter("@Category", "");
                    SqlParameter param4 = new SqlParameter("@Title", Convert.ToString(id));
                    var medias = db.Database.SqlQuery<LibraryMediaEntry>("exec SP_TITILESEARCH @FLAG,@Author,@Category,@Title", param1, param2, Param3, param4).ToList();