模型属性将不会更新，验证错误呼吁单独的属性不更新？ [英] Model Attribute Won't Update, Validation Error Called On Separate Attribute Not Being Updated?

问题描述

我有以下的半先进的数据库查询，是要通过每小时的价格在过去的10年，回到日平均价格为过去七天：

I have the following semi-advanced DB query that is going through hourly prices for the last 10 years and returning daily average prices for the last seven days:

averages = Trade.where('date >= ?', 7.days.ago).average(:price, :group => "DATE_TRUNC('day', date - INTERVAL '1 hour')")

这将返回日期（这一天）和 averageprice 是这样的：

This returns the date (for that day) and an averageprice like this:

"2012-12-29 00:00:00"=>#<BigDecimal:7f97932be328,'0.2513458333 33333333E2',27(27)>

我然后通过每个响应循环，并将其保存为一个TradeDailyAverage型号新记录。

I then loop through each response and save them as new records in a TradeDailyAverage Model.

    # Loops through each daily average produced above 
    averages.each do |date, avg|

     # Converts the BigDecimal to Floating Point(?)
     averagefloat = avg.to_f

     # Rounds the Daily Average to only two decimal points
     dailyaverage = number_with_precision(averagefloat, :precision => 2)

     # Creates a new Object in the PpDailyAverage table  
     TradeDailyAverage.create(date: date, averageprice: dailyaverage)

这工作，但由于这将是一个小时的 Rake任务，新的价格进来的每一个小时，我怎样才能改变这种先找到一个TradeDailyAverage通过日期键，如果存在的话，请更新 averageprice 属性，或创建一个新的记录，如果它不存在。

This works, but since this will be an hourly Rake Task, with new prices coming in every hour, how can I change this to first find a TradeDailyAverage by date and if it exists, update the averageprice attribute, or create a new record if it doesn't exist.

Validate_uniqueness坐落于TradeDailyAverage模型。

Validate_uniqueness is set on TradeDailyAverage Model.

更新

当我这样做，7项出现，具有精确的平均值。但是，他们是不会保存。当我添加 newaverage.save 我得到的验证错误：日期已经采取了！

When I do this, 7 items appear, with accurate averages. But they just won't save. When I add newaverage.save! I get a "Validation Error: Date has already been taken!"

 newaverage = TradeDailyAverage.find_or_initialize_by_date(date: date)
          newaverage.averageprice = dailyaverage
          puts newaverage.date
          puts newaverage.averageprice

另外，如果我做newaverage.new_record？自从平均返回TRUE

Also, if I do newaverage.new_record? Ever average returns TRUE

推荐答案

这个问题（感谢亚历克斯的帮助）是由于在日期时间的差异。一旦保存到PG分贝，小时将更改日期时间。这可能是由于在分贝一个时区的问题。因此，code以上未能找到现有的记录，因为它包含了不同小时的时间比已保存在数据库中。

The issue (thanks to Alex's help) was due to a difference in the datetimes. Upon saving to a PG db, the hour would change on the datetime. This may be due to a timezone issue in the db. So, the code above could not find existing records, since it contained a different hourly time than what has been saved in the database.

由于我生产的日平均值，我不需要的时候，只要在日期列中的日期。于是，我将我的日期，以日期，以避免时间差的问题。此外，我改变了codeA位用的情况下，这样我可以报告错误。我不认为这是非常有效的，但它的工作现在。我相信，亚历克斯的解决方案上面还可以工作，只要日期时间值转换为日期与 .to_date ：

Since I am producing daily averages, I don't need the time, just the date in the date column. So, I converted my dates to date to avoid the time difference issue. Also I changed the code a bit with a Case, so that I can report errors. I don't think this is very efficient, but it is working for now. I believe Alex's solution above may also work as long as the datetime values are converted to dates with .to_date:

# Loops through each daily average produced above 
    averages.each do |datetime, avg|

    # Converts the BigDecimal to Floating Point(?)
    avgfloat = avg.to_f

    # Rounds the Daily Average to only two decimal points
    avgprice = number_with_precision(avgfloat, :precision => 2)

    # Converts datetime to date since this will not work with datetime (PostgreSQL is time-zoned challenged)    
    avgdate  = datetime.to_date

        # These are printed to use for testing. 
      puts avgdate
      puts avgprice

      # Starts Case to either report an error, update an existing record, or create new.
      case

        when avgdate.blank? || avgprice.blank?
            puts "Something went terribly wrong with your seven day averages producing algorithm."

        when TradeDailyAverage.exists?(:date=>avgdate)
            updateavg = TradeDailyAverage.find_by_date(avgdate)
            updateavg.averageprice = avgprice
            updateavg.save

        else
            TradeDailyAverage.create(:date=>avgdate, :averageprice=>avgprice)

        end # Ends Case  

    end # Ends Loop for each Daily Average 

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