替换哈希值

Question

我有一系列哈希：

[{"__content__"=>"Guitars", "id"=>"2"},
 {"__content__"=>"For Guitars", "id"=>"3", "parentId"=>"2"},
 {"__content__"=>"6-string", "id"=>"24", "parentId"=>"2"},
 {"__content__"=>"7-string", "id"=>"25", "parentId"=>"2"},
 {"__content__"=>"8-string", "id"=>"26", "parentId"=>"2"}]

我想将parentId值替换为__content__值，以获取：

[{"__content__"=>"Guitars", "id"=>"2"},
 {"__content__"=>"For Guitars", "id"=>"3", "parentId"=>"Guitars"},
 {"__content__"=>"6-string", "id"=>"24", "parentId"=>"Guitars"},
 {"__content__"=>"7-string", "id"=>"25", "parentId"=>"Guitars"},
 {"__content__"=>"8-string", "id"=>"26", "parentId"=>"Guitars"}]

我该怎么做？

Answer 1

我更喜欢将这个禁止的array更改为hash以便更好地制作maping。

<强>输入

arr = [
  {"__content__" => "Guitars", "id" => "2"},
  {"__content__" => "For Guitars", "id" => "3", "parentId" => "2"},
  {"__content__" => "6-string", "id" => "24", "parentId" => "2"},
  {"__content__" => "7-string", "id" => "25", "parentId" => "2"},
  {"__content__" => "8-string", "id" => "26", "parentId" => "2"}
]

创建父母

parents = arr.each_with_object({}) { |h, exp| exp[h['id']] = h['__content__'] }

在这个良好的地图结构之后，您只需使用map方法。

<强>过程

output = arr.map do |h|
  h['parentId'] = parents[h['parentId']] if h['parentId'] && parents[h['parentId']]
  h
end

<强>输出

p output

# [
#   {"__content__" => "Guitars", "id" => "2"},
#   {"__content__" => "For Guitars", "id" => "3", "parentId" => "Guitars"},
#   {"__content__" => "6-string", "id" => "24", "parentId" => "Guitars"},
#   {"__content__" => "7-string", "id" => "25", "parentId" => "Guitars"},
#   {"__content__" => "8-string", "id" => "26", "parentId" => "Guitars"}
# ]

我希望这会有所帮助。

修改

你也可以这样使用

按ID排序

arr.sort_by! { |h| h['id'] }

<强>过程

output = arr.each_with_object({}) do |h, exp|
    exp[h['id']] = h
    h['parentId'] = exp[h['parentId']]['__content__'] if h['parentId'] && exp[h['parentId']]
    h
  end

在此之后你将拥有像键一样的id哈希，所以对你的输出：

<强>输出

p output.values

# [
#  {"__content__"=>"Guitars", "id"=>"2"},
#  {"__content__"=>"6-string", "id"=>"24", "parentId"=>"Guitars"},
#  {"__content__"=>"7-string", "id"=>"25", "parentId"=>"Guitars"}, 
#  {"__content__"=>"8-string", "id"=>"26", "parentId"=>"Guitars"},
#  {"__content__"=>"For Guitars", "id"=>"3", "parentId"=>"Guitars"}
# ]

Answer 2

小心！下面的解决方案改变了原始哈希！

▶ hashes = [{"__content__"=>"Guitars", "id"=>"2"},
▷   {"__content__"=>"For Guitars", "id"=>"3", "parentId"=>"2"}, 
▷   {"__content__"=>"6-string", "id"=>"24", "parentId"=>"2"}, 
▷   {"__content__"=>"7-string", "id"=>"25", "parentId"=>"2"}, 
▷   {"__content__"=>"8-string", "id"=>"26", "parentId"=>"2"}]   

hashes.each_with_object({}) do |h, memo|
  memo[h['id']] = h['__content__']
  h['parentId'] = memo[h['parentId']]
end

hashes
#⇒ [{"__content__"=>"Guitars", "id"=>"2", "parentId"=>nil},
#   {"__content__"=>"For Guitars", "id"=>"3", "parentId"=>"Guitars"},
#   {"__content__"=>"6-string", "id"=>"24", "parentId"=>"Guitars"},
#   {"__content__"=>"7-string", "id"=>"25", "parentId"=>"Guitars"},
#   {"__content__"=>"8-string", "id"=>"26", "parentId"=>"Guitars"}]

Answer 3

arr = [{"__content__"=>"Guitars", "id"=>"2"}, {"__content__"=>"For Guitars", "id"=>"3", "parentId"=>"2"}]

id_content_mapping = arr.reduce({}) do |h, elt|
  h[elt["id"]] = elt["__content__"]
  h
end

arr.map do |elt|
  if elt.has_key? "parentId"
    elt["parentId"] = id_content_mapping[elt["parentId"]]
  end
  elt
end