ruby - 如何将平面 Ruby 散列解析为嵌套散列?
问题描述
我有以下平面 Ruby 哈希:
{
"builder_rule_0_filter"=>"artist_name",
"builder_rule_0_operator"=>"contains",
"builder_rule_0_value_0"=>"New Found Glory",
"builder_rule_1_filter"=>"bpm",
"builder_rule_1_operator"=>"less",
"builder_rule_1_value_0"=>"150",
"builder_rule_2_filter"=>"days_ago",
"builder_rule_2_operator"=>"less",
"builder_rule_2_value_0"=>"40",
"builder_rule_3_filter"=>"release_date_start",
"builder_rule_3_operator"=>"between",
"builder_rule_3_value_0"=>"2019-01-01",
"builder_rule_3_value_1"=>"2019-12-31",
}
我想将其转换为更有条理/可用的嵌套哈希:
{
"0"=>
{
"filter"=>"artist_name",
"operator"=>"contains",
"values"=>
{
"0"=>"New Found Glory"
}
},
"1"=>
{
"filter"=>"bpm",
"operator"=>"less",
"values"=>
{
"0"=>"150"
}
}
"2"=>
{
"filter"=>"days_ago",
"operator"=>"less",
"values"=>
{
"0"=>"40"
}
}
"3"=>
{
"filter"=>"release_date_start",
"operator"=>"between",
"values"=>
{
"0"=>"2019-01-01"
"1"=>"2019-12-31"
}
}
}
那么,如何转换平面哈希(我从表单中获取)并根据这些键名将其转换为嵌套?
解决方案
首先,您可以根据前缀编号将散列拆分为多个散列(随意运行此命令以查看返回值)
groups = input.
group_by { |k,v| k.match(/builder_rule_(\d+)/)[1] }.
transform_values(&:to_h)
此时,如果您只使用一些硬编码来构建 key-valls,那么创建内部对象会更容易:
result = groups.each_with_object({}) do |(prefix, hash), memo|
memo[prefix] = {
"filter" => hash["builder_rule_#{prefix}_filter"],
"operator" => hash["builder_rule_#{prefix}_operator"],
"values" => hash.select do |key, val|
key =~ /builder_rule_#{prefix}_value/
end.sort_by { |key, val| key }.map { |(key, val)| val }
}
end
可能会混淆什么.sort_by { |key, val| key }.map { |(key, val)| val }
意思。我可以拼写出来:
hash.select { |key, val| key =~ /builder_rule_#{prefix}_value/ }
获取将用于“值”数组的键值。它返回一个哈希。.sort_by { |key, val| key }
将散列转换为元组数组[key, val]
,按键排序。这是为了使这些值以正确的顺序出现。.map { |(key, val)| val }
将嵌套数组转换为单级数组,丢弃键
您也可以使用sort_by(&:first).map(&:second)
,尽管您需要积极的支持才能使用Array#second