azure-sql-database - 机器人模拟器 "ExceptionMessage": "Object reference not set to an instance of an object.", "exceptionType": "System.NullReferenceException",

Question

我想将对话存储在聊天机器人上并为此使用 IActivityLogger。代码如下:

public class EntityFrameworkActivityLogger : IActivityLogger
{
    Task IActivityLogger.LogAsync(IActivity activity)
    {
        IMessageActivity msg = activity.AsMessageActivity();
        using (BotApplicationSqlData.ConversationDataContext dataContext = new BotApplicationSqlData.ConversationDataContext())
        {
            var newActivity = Mapper.Map<IMessageActivity, BotApplicationSqlData.Activity>(msg);
            if (string.IsNullOrEmpty(newActivity.Id))
                newActivity.Id = Guid.NewGuid().ToString();
            dataContext.Activities.Add(newActivity);
            dataContext.SaveChanges();
        }
        return null;
    }
}

我收到请求错误

'https://botapplicationsqlexample.azurewebsites.net/api/messages' failed: [500] Internal Server Error .

在调试时，它显示了一个Null Reference Exception 和Object reference not set to an instance of an object。

对话正在存储在 Azure 数据库中，但机器人端没有回复。谁能帮我解决这个问题？

Answer 1

我运行了这段代码，发现如果 ActivityTypes.Typing 类型的事件通过，activity.AsMessageActivity() 会返回一个空对象。要解决这个问题，只需用空检查包围保存代码:

    public async Task LogAsync(IActivity activity)
    {
        IMessageActivity msg = activity.AsMessageActivity();

        if (msg != null)
        {
            using (Data.ConversationDataContext dataContext = new Data.ConversationDataContext())
            {
                var newActivity = Mapper.Map<IMessageActivity, Data.Activity>(msg);
                if (string.IsNullOrEmpty(newActivity.Id))
                    newActivity.Id = Guid.NewGuid().ToString();

                dataContext.Activities.Add(newActivity);
                dataContext.SaveChanges();
            }
        }
    }