Question

我的开发环境：

Ubuntu 9
Ruby 1.9.1 / 1.8.7（rvm）
Rails 2.3.5
Mysql 5.0
Apache Passenger

以下是代表问题的程序流程的一部分。

请求来了：

#action
def create
  begin
    @report = Report.new(params[:report])
    ...  
  rescue LocationNotFound => e
    ...
  end
end

报告构造函数：

class Report
  attr_accessor :locations

  def initialize(params = {})
    @locations = params[:locations] ? fetch_locations(params[:locations]) : []
  end
  ...
end

fetch_locations：

def fetch_locations(loc_names)
  Rails.logger.debug "LOC_NAMES: " + loc_names.inspect
  ls = Location.find(:all, :conditions => [ # line 57
    "locations.name in (#{loc_names.map{'?'}.join(',')})",
    *loc_names
  ], :include => [:sample_summaries, :samples]) # loc_names will never be empty
  ...
end

位置模型：

class Location < ActiveRecord::Base
  has_many :sample_summaries
  has_many :samples, :through => :sample_summaries
  ...
end

现在，第一次（在乘客重新启动后）这个运行正常并完成工作。在大多数情况下，我都会收到错误：

Mar-11 11:01:00 #15098 DEBUG: LOC_NAMES: ["Moscow, RF", "London, UK"]
Mar-11 11:01:00 #15098 DEBUG:   Location Load (0.0ms)   SELECT * FROM `locations` WHERE (locations.name in ('Moscow, RF','London, UK'))
Mar-11 11:01:00 #15098 DEBUG:   SampleSummary Load (0.0ms)   SELECT `sample_summaries`.* FROM `sample_summaries` WHERE (`sample_summaries`.location_id IN (1,3))
Mar-11 11:01:00 #15098 DEBUG:   SampleSummary Columns (0.0ms)   SHOW FIELDS FROM `sample_summaries`
Mar-11 11:01:00 #15098 FATAL:
NoMethodError (You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.include?):
  app/models/report.rb:57:in `fetch_locations'
  app/models/report.rb:9:in `initialize'
  app/controllers/report_controller.rb:11:in `new'
  app/controllers/report_controller.rb:11:in `create'

对我来说很随意。有什么想法吗？

P.S。我还尝试将查询包装在uncached块中，但这并未改变任何内容。

修改

以下是SampleSummary模型的样子：

class SampleSummary < ActiveRecord::Base
  has_many :samples
  belongs_to :location
  ... #validations

  default_scope :include => :samples, :order => 'rss_ts desc'
  ...
end

EDIT2

它在控制台中不会失败。

Answer 1

那么，如果你通过./script/console（控制器动作的相关部分）多次使用相同的参数运行它，它会随机失败？或者它一直都失败了？目前尚不清楚。

随便，为什么不试试......

ls = Location.find（：全部，：conditions =＆gt; [“（。）中的locations.name”，loc_names]，：include =＆gt; ：sample_summaries =＆gt; {：samples}）

Answer 2

由于sample_summaries的默认范围包括样本，您可以尝试：

def fetch_locations(loc_names)
  ls = Location.find(:all, 
    :conditions => {:locations => {:name => loc_names}, 
    :include => :sample_summaries
  )
end

另外，如果你完全离开：include off，它会失败吗？

Answer 3

这就是它发生的事情：

https://rails.lighthouseapp.com/projects/8994/tickets/1339-arbase-should-not-be-nuking-its-children-just-because-it-lost-interest

好消息是，它只发生在开发模式（config.cache_classes = false）。将其更改为true将使其消失（代价是每次更改后都不会忘记重新启动服务器）。

来自ActiveRecord的奇怪错误（可能）

3 个答案: