使用存储过程时,对象引用未设置为对象的实例

Question

这是一个.cs页面,我有两个函数要执行,但错误是函数没有被执行,如果我评论一个函数,另一个将工作,两个都没有执行,它给出一个常见的错误 object reference not set to an instance of an object

下面指定的是.cs页面.

Business bus = new Business();

try
{
    intResult = bus.create_user(ua);
}
catch (Exception ex)
{

}
finally
{
    bus = null;
}

int intres = 0;

try
{
    intres = bus.fninsertuser_role_map(ua, role, i);

}
catch (Exception ee)
{

}
finally
{
    bus = null;
}

数据访问对象

public int create_user(UserMaster ua)
{
    //  Connection connect = new Connection();
    try
    {
        return cs.create_user(ua);

    }
    catch (Exception e)
    {
        throw e;
    }
    finally
    {
        cs = null;
    }

}

public int fninsertuser_role_map(UserMaster ua, int[] role, int i)
{
    //  Connection connect = new Connection();
    try
    {
        return cs.fninsertuser_role_map(ua, role, i);

    }
    catch (Exception e)
    {
        throw e;//**Throws the exception here.**
    }
    finally
    {
        //cs = null;
    }

商业价值对象

public int create_user(UserMaster ua)
{
    SqlConnection Con = new SqlConnection(str);
    Con.Open();
    SqlCommand Cmd = new SqlCommand("createuser", Con);
    Cmd.CommandType = CommandType.StoredProcedure;
    try
    {
        log.Debug("Inside Create user");
        Cmd.Parameters.AddWithValue("@User_Id", ua.UserName);
        Cmd.Parameters.AddWithValue("@Password", ua.Password);
        Cmd.Parameters.AddWithValue("@Name", ua.Name);
        Cmd.Parameters.AddWithValue("@Role_Id", ua.Role);
        Cmd.Parameters.AddWithValue("@Department_Id", ua.Department);
        Cmd.Parameters.AddWithValue("@Active", ua.Active);
        log.Debug("Inside Create_User: New User created having ID: " + ua.UserName);
        log.Info("user created");
        return Cmd.ExecuteNonQuery();
    }
    catch (Exception e)
    {
        log.Debug("Error: Inside catch block of Create User");
        log.Error("Error msg:" + e);
        log.Error("Stack trace:" + e.StackTrace);

        throw e;
    }
    finally
    {
        Cmd.Dispose();
        Con.Close();
        Con.Dispose();
    }


}

/*Function to insert into user_role_map*/

public int fninsertuser_role_map(UserMaster u, int[] role, int i)
{
    SqlConnection Con = new SqlConnection(str);
    Con.Open();
    transaction = Con.BeginTransaction();
    int result = 0;


    for (int a = 0; a < i; a++)
    {
        SqlCommand Cmd = new SqlCommand("create_UR_Map", Con, transaction);
        Cmd.CommandType = CommandType.StoredProcedure;
        Cmd.Parameters.Clear();
        Cmd.Parameters.AddWithValue("@User_Id", u.UserName);
        Cmd.Parameters.AddWithValue("@Role_Id", role[a]);


        result = Cmd.ExecuteNonQuery();
    }
    transaction.Commit();

    return result;

}

我只需要在同一页面中执行这两个功能.非常感谢.

Answer 1

问题:您正在尝试放入null实例变量bus,然后使用相同的变量调用方法,如下所示:

try
{
    intResult = bus.create_user(ua);
}
catch (Exception ex)
{

}
finally
{
    bus = null;//bus becomes null here for sure even if there is no excption thrown
}

int intres = 0;

try
{
    intres = bus.fninsertuser_role_map(ua, role, i);//throws exception here

}

这就是它抛出的原因object reference not set to an instance of an object.

注意:您应该记住,finally无论情况如何都将执行该块意味着它将在所有情况下执行,并且即使没有抛出异常,您的实例变量也会bus变得null确定.

解决方案:我认为你需要真正重构你的代码,但你的意图是将实例变量bus设为null如果它抛出异常,如果是在catch块中移动该语句的情况.

试试这个:

try
{
    intResult = bus.create_user(ua);
}
catch (Exception ex)
{
    bus = null;
}
finally
{
    //any code which needs to be executed for sure
}

int intres = 0;

try
{
    intres = bus.fninsertuser_role_map(ua, role, i);

}
catch (Exception ee)
{
  bus = null;
}
finally
{
    //any code which needs to be executed for sure
}