Rails - 可枚举的Group_By多个关联 [英] Rails - Enumerable Group_By multiple associations

问题描述

我想通过它们有很多关系来分组对象的集合...像这样

I want to group a collection of objects by their has many relations... like this

s.inventoryitems.group_by{|i| i.locations}

为简单起见，这会返回如下所示的结果：

For the sake of simplicity this returns me something like this:

{[1, 2, 3]=>["a"], [2]=>["b", "c"], []=>["d"]}

这虽然：

I'm looking for a result like this though:

{[1] => ["a"], [2] => ["a","b","c"], [3] => ["a"], [] => ["d"]}

我正在重组事物，所以这些都可以在更多直观的DB&模型关联导向的方式，但同时我需要立即实现这一点，需要用一些Ruby来对其进行讨论，但我不确定。感谢您的帮助！

I am working on restructuring things so this can all be done in a more intuitive DB & model association oriented way, but in the meantime I need implement this immediately and need to wrangle it with some Ruby and am not sure. Thanks for any help!

推荐答案

您需要展开此操作，将其反转并重新对其进行分组，像那样的结构。你可以简单地通过遍历它并手动重新组合：

You need to expand this, invert it, and re-group it if you want to flip the structure like that. You could do this simply by iterating over it and regrouping manually:

h = { [ 1, 2, 3 ] => [ "a" ], [ 2 ] => [ "b", "c" ], [ ] => [ "d" ] }
s = { }

h.each do |keys, values|
  keys.each do |key|
    values.each do |value|
      s[[ key ]] ||= [ ]
      s[[ key ]] << value
    end
  end

  if (keys.empty?)
    s[[ ]] = values
  end
end

puts s.inspect
# => {[1]=>["a"], [2]=>["a", "b", "c"], [3]=>["a"], []=>["d"]}

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