异常处理 - 有更好的方法吗？

Question

public bool AddEntity(int ParentId, 字符串描述) { 尝试 { _connection.Open(); SqlCommand 命令 = new SqlCommand("INSERT 结构（路径，描述）" + "VALUES(" + GetPath(parentId) + ".GetDescendant(" + GetLastChildPath(parentId, 1) + ", NULL), " + 描述+“）”，_连接）；

            if (command.ExecuteNonQuery() <= 0) _success = false;

            command.Connection.Close();

            if (_success)
            {
                return true;
            }

            throw new Exception("An error has occured whilst trying to add a entity");
        }
        catch (Exception ex)
        {
            AddError(new ErrorModel("An error has occured whilst trying to add a entity", ErrorHelper.ErrorTypes.Critical, ex));
            return false;
        }
    }

有没有更好的方法来处理上面示例中的异常？

预先感谢您的任何帮助。

克莱尔

Answer 1

这里有很多问题。

一个。您正在使用内联 SQL 并将我只能假设为用户生成的数据注入其中。这是一个安全风险。使用参数化查询。

b.您的异常处理没问题，但是如果发生错误，这将使连接保持打开状态。我会这样写：

 public bool AddEntity(int parentId, string description)
 {
    try
    {
        //Assuming you have a string field called connection string
        using(SqlConnection conn = new SqlConnection(_connectionString))
        {
            SqlParameter descriptionParam = new SqlParameter("@description", SqlDbType.VarChar, 11);
            descriptionParam.Value = description;

            SqlParameter parentIdParam = new SqlParameter("@parentId", SqlDbType.Int, 4);
            parentIdParam.Value = parentId;

            //Bit confused about the GetPath bit.
            SqlCommand command = new SqlCommand("INSERT Structure (Path,Description) " +
                                            "VALUES(" + GetPath(parentId) + ".GetDescendant(" + GetLastChildPath(parentId, 1) + ", NULL),@description)", conn);

            command.Parameters.Add(descriptionParam);

            if (command.ExecuteNonQuery() <= 0) _success = false;
        }

        if (_success)
        {
            return true;
        }

        //This isn't really an exception. You know an error has a occured handle it properly here.
        throw new Exception("An error has occured whilst trying to add a entity");
    }
    catch (Exception ex)
    {
        AddError(new ErrorModel("An error has occured whilst trying to add a entity", ErrorHelper.ErrorTypes.Critical, ex));
        return false;
    }

Answer 2

您可以利用 IDisposable 接口以及 using 块的强大功能。

using(var connection = new Connection()) // Not sure what _connection is, in this method, so making pseudo-code
{
  // ... work with connection
}

即使抛出异常，这也会关闭连接。它变成（或多或少）这样：

var connection = new Connection();

try
{
  // ... work with connection
}
finally
{
  connection.Dispose();
}

在这种情况下，Dispose 将关闭连接。