显示异常，无法将对象从DBNull强制转换为其他类型。

问题描述

private void SaveData()
       {
       try
           {
               objVehicleCategory = new VehicleCategoryPresenter();
               if (Session["CorporateID"] != null)
               {
                   CorporateID = Convert.ToInt32(Session["CorporateID"]);
               }

            int result= objVehicleCategory.SaveData( txtVehicleCategory.Text,Convert.ToInt32 (txtVehicleCategory1.Text), txtDescription.Text,CorporateID);
            if (result == 1)
            {
                ucPageHeader.DisplayMessage = Resources.Messages.SaveSuccess;
            }
            else if (result == 2)
            {
                ucPageHeader.DisplayMessage = Resources.Messages.VehicleCategoryExist;
            }
            else
            {
                ucPageHeader.DisplayMessage = Resources.Messages.SaveFailed;
            }
            txtVehicleCategory.Text = string.Empty;

                   txtDescription.Text=string.Empty;
           }
           catch (Exception ex)
           {

           }
       }
  

 public int SaveData( string CategoryName,int NumberOfSeats, string Description,int CorporateID)
        {
            return objVehicleCategory.SaveData( CategoryName, NumberOfSeats, Description,CorporateID);
        }



<pre lang="cs">public int SaveData( string CategoryName,int NumberOfSeats, string Description,int CorporateID)
        {
            try
            {
                var outputParameter = new ObjectParameter("VehicleCategoryID", typeof(Int32));
                objEntity.usp_VehicleCategory_Insert(outputParameter, CategoryName, NumberOfSeats, Description, CorporateID);
                return Convert.ToInt32(outputParameter.Value);
            }
            catch (Exception ex)
            {
                return 0;
            }
        }

public virtual int usp_VehicleCategory_Insert（ObjectParameter vehicleCategoryID，string categoryName，Nullable< int> numberOfSeats，string description，Nullable< int> corporateID）

{

var categoryNameParameter = categoryName！= null？

new ObjectParameter（CategoryName，categoryName）：

new ObjectParameter（CategoryName，typeof（string））;



var numberOfSeatsParameter = numberOfSeats.HasValue？

new ObjectParameter（NumberOfSeats，numberOfSeats）：

new ObjectParameter（NumberOfSeats，typeof（int））;



var descriptionParameter = description！= null？

new ObjectParameter（Description，description）：

new ObjectParameter（Description，typeof（string））;



var corporateIDParameter = corporateID.HasValue？

new ObjectParameter（CorporateID，corporateID）：

新的ObjectParameter（CorporateID，typeof（int））;



return（（IObjectContextAdapter）this）.ObjectContext.ExecuteFunction（usp_VehicleCategory_Insert， vehicleCategoryID，categoryNameParameter，numberOfSeatsParameter，descriptionParameter，corporateIDParameter）;

}

public virtual int usp_VehicleCategory_Insert(ObjectParameter vehicleCategoryID, string categoryName, Nullable<int> numberOfSeats, string description, Nullable<int> corporateID)
{
var categoryNameParameter = categoryName != null ?
new ObjectParameter("CategoryName", categoryName) :
new ObjectParameter("CategoryName", typeof(string));

var numberOfSeatsParameter = numberOfSeats.HasValue ?
new ObjectParameter("NumberOfSeats", numberOfSeats) :
new ObjectParameter("NumberOfSeats", typeof(int));

var descriptionParameter = description != null ?
new ObjectParameter("Description", description) :
new ObjectParameter("Description", typeof(string));

var corporateIDParameter = corporateID.HasValue ?
new ObjectParameter("CorporateID", corporateID) :
new ObjectParameter("CorporateID", typeof(int));

return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction("usp_VehicleCategory_Insert", vehicleCategoryID, categoryNameParameter, numberOfSeatsParameter, descriptionParameter, corporateIDParameter);
}

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