c# - 编写具有良好 C# 语法的简单 bool 方法的最佳方法

Question

大家好，我好像到处都有这种方法。

下面的方法想要完成这些简单的任务:

1. 打开数据库连接(IntLMPDB 对象)
2. 从一个小的数据库表中读取一条简单的记录(数据库表以字符串作为键，因为每个字符串都是方法的名称，所以我只需要表中的每一行)，该行的其余部分是一系列时间戳，告诉我事情何时发生。
3. 如果找不到记录，则返回异常，因为无能为力。
4. 如果您找到记录，请查看第二个日期(如果它只是明显缺失)，然后设置为 true，因为这是有史以来第一次运行。
5. 或者最后进入正题，如果第一个日期大于第二个日期，则将其设置为 True，因为它已经更新并且该运行了。否则，如果没有，则设置为 False，因为还没有更新。

所以这是代码...我正在尝试做的是将其缩减为运行这些检查的最佳和最快的方法。我不关心数据库连接问题或类似问题。

    private static bool isLastIntervalNewerThanDB(string muiMethod)
    {
       using (var db = new IntLMPDB())
        {
            // Try to load a matching record.
            LastIntervalUpdated liRec = db.LastIntervalUpdateds.FirstOrDefault(rec => rec.method == muiMethod);
            // If it could not be loaded, exit because there's no way to determine if we should run.
             if (liRec == null) { throw new Exception(string.Format("Could NOT find LastIntervalUpdated record for muiMethod: {0}", muiMethod)); }
            else
            {
                // we have a valid interval record, so lets check that it has been updated since the last webPostTime.
                // put another way, there are three datetime values in the LastIntervalUpdated table. First is the
                // interval itself, second is the retrievalTime and third is the webPostTime. Whenever the MUI is 
                // checked for a new interval if one is found then the code updates the retrievalTime to the current
                // instant in time. This tells us what the last interval this application found on its last run was.
                // The thrid value is the webPostTime, this time instant is only updated by this very method we're in
                // right here. We can use this logic: if the retrievalTime is greater than the webPostTime then there's
                // a newer interval that we haven't yet processed and inserted into the databse. So we should run the
                // method below and update ALL of the syncable values into the databse. Then we'll set the dbPostTime to 
                // the current instance. As it goes, if this program then runs again before the interval is updated
                // then the dbPostTime will be greater than the retrieval time and we'll know to do nothig. Simple Right? :)

                // or check here includes a NULL check on dbPostTime because it's possible that dbPostTime is NULL,
                // in the example of the first time the system runs. It might have run a LastUpdate sync and not yet
                // done this method, so dbPostTime would be NULL. None of the other columns are allowed to be null.
                if (liRec.dbPostTime_EST == null || liRec.retrievalTime_EST > liRec.dbPostTime_EST)
                { return true; }
                else { return false; }
            }
       }
    }

Answer 1

我觉得逻辑没问题。我建议你做这样的事情来提高可读性*:

private static bool isLastIntervalNewerThanDB(string muiMethod)
{
   using (var db = new IntLMPDB())
    {
        LastIntervalUpdated liRec 
            = db.LastIntervalUpdateds
                    .FirstOrDefault(rec => rec.method == muiMethod);

        if (liRec == null) 
        { 
            throw new Exception(
                string.Format("Could NOT find LastIntervalUpdated record for muiMethod: {0}", muiMethod)); 
        }

        return liRec.dbPostTime_EST == null 
            || liRec.retrievalTime_EST > liRec.dbPostTime_EST;        
   }
}

*虽然可读性是主观的，但我认为 if (liRec == null) 之后的 else 只会添加不必要的嵌套并且可以折叠最终条件成一个单一的表达。也永远不要低估长表达式中位置恰当的换行符 - 它可以使代码的可读性和不可读性完全不同。