NoMethodError：未定义的方法`<<'为零：NilClass

我有一个任务，我没有建立，但不再工作。我是新来的红宝石轨道上，还没有找到这个问题的解决方案呢。NoMethodError：未定义的方法`<<'为零：NilClass

当我运行任务获得：

这是任务：

小调试通控制台

确认有120530个负载转移：

loads = Load.where("pickup < NOW()").count  
2014-07-23 12:55:56 DEBUG -- (149.8ms) SELECT COUNT(*) FROM "loads" WHERE (pickup < NOW()) 
=> 120530

创建空arr AY：

expired_loads = [] 
=> []

运行where命令

loads = Load.where("pickup < NOW()")

许许多多的记录......我也仅限于两个用于测试

1.9.3-p547 :006 > loads = Load.where("pickup < NOW()").limit(2) 
2014-07-23 13:02:07 DEBUG -- Load Load (74.2ms) SELECT "loads".* FROM "loads" WHERE (pickup < NOW()) LIMIT 2 
=> [#<Load id: 18398947, user_id: 11074, origin: #<RGeo::Geographic::SphericalPointImpl:0x595f056 "POINT (-80.48237609863281 37.772544860839844)">, dest: #<RGeo::Geographic::SphericalPointImpl:0x595ec64 "POINT (-78.30302429199219 40.295894622802734)">, length: 48, comments: "~PostEverywhere_20140721140916~", ltl: false, rate: nil, delivery: "2014-07-22 17:00:00", pickup: "2014-07-21 17:00:00", weight: 48, equipment_id: 8, covered: false, created_at: "2014-07-21 19:16:16", updated_at: "2014-07-21 19:16:16", owner: nil, deleted: false, origin_city: "ronceverte", origin_state: "wv", dest_city: "martinsburg", dest_state: "pa">, #<Load id: 18398948, user_id: 11074, origin: #<RGeo::Geographic::SphericalPointImpl:0x553cd2a "POINT (-81.035400390625 37.384891510009766)">, dest: #<RGeo::Geographic::SphericalPointImpl:0x553c9d8 "POINT (-79.80570983886719 40.317527770996094)">, length: 48, comments: "~PostEverywhere_20140721140916~", ltl: false, rate: nil, delivery: "2014-07-22 17:00:00", pickup: "2014-07-21 17:00:00", weight: 48, equipment_id: 8, covered: false, created_at: "2014-07-21 19:16:16", updated_at: "2014-07-21 19:16:16", owner: nil, deleted: false, origin_city: "princeton", origin_state: "wv", dest_city: "greenock", dest_state: "pa">]

真的不知道该< <是什么但我认为这只是分布的属性，以便他们可以保存在另一个表

这里

**NoMethodError: undefined method `<<' for nil:NilClass**

下一行

loads.each {|load| expired_loads << load.attributes }

错误是：将它们保存到archived_loads表和负载表中删除

ArchivedLoad.create(expired_loads) 
loads.delete_all

来源

2014-07-23 Big Al Ruby Newbie

为什么不使用#map呢？ expired_loads = loads.map(&:attributes)或更好，但只需在Load中创建一个方法即可将其归档，例如

class Load 
    scope :expired_loads, -> {where("pickup < NOW()")} 
    def self.archive_now 
    ArchiveLoad.create(expired_loads.map(&:attributes)) 
    expired_loads.delete_all 
    end   
end

然后就可以调用Loads.archive_now我不确定你的任何结构，这仅仅是一个建议，以更简洁的方式。

如果您还在里面使用了<<方法，也可以谨慎地发布您的ArchivedLoad的create方法。如果你还没有实现某种自定义的create方法，我认为你需要一个迭代，而不是如

expired_loads.map(&:attributes).each{|load| ArchiveLoad.create(load)}

而且<<类似于push它添加一个对象的Array

结束

来源

2014-07-23 18:37:20 engineersmnky

NoMethodError：未定义的方法`<<'为零：NilClass

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