从nvarchar值到数据类型int的转换失败?

CREATE TYPE ItemTableType AS TABLE   
( 
  BrandId INT, 
  BranchId INT,
  InventoryCategoryId INT,
  Attributes nvarchar(Max),
  Price Decimal(18,2),
  [Description] nvarchar(Max)
); 

我在C代码中创建了一个数据表,如下所示

 var dt = new DataTable();
            dt.Columns.Add("BrandId");
            dt.Columns.Add("BranchId");
            dt.Columns.Add("attributes");
            dt.Columns.Add("InventoryCategoryId");
            dt.Columns.Add("Price");
            dt.Columns.Add("Description");

            foreach (var item in inventoryItems)
            {
                DataRow r = dt.NewRow();
                r["BrandId"] = item.BrandId;
                r["BranchId"] = item.BranchId;
                r["InventoryCategoryId"] = item.InventoryCategoryId;
                r["attributes"] = item.Attributes;
                r["Price"] = item.Price;
                r["Description"] = item.Description;
                dt.Rows.Add(r);

            }

当我尝试将dt传递到SP时,我得到

{System.Data.SqlClient.SqlException (0x80131904): Conversion failed when converting the nvarchar value '{"PartNumber":"XA1167","Qty":999,"CleanedPartNumber":"1167"}' to data type int.


The data for table-valued parameter "@Source" doesn't conform to the table type of the parameter. SQL Server error is: 245, state: 1
The statement has been terminated.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite, String method)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite, String methodName)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at line 202
ClientConnectionId:7a91a363-e5a0-4476-a92f-d02c30262728
Error Number:245,State:1,Class:16}