将列表解析为地图答案

【问题标题】：Parsing a list into a map将列表解析为地图
【发布时间】：2019-02-02 00:22:50
【问题描述】：

我从plug`conn.req_headers 收到以下回复：

[
  {"accept",
   "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8"},
  {"accept-encoding", "gzip, deflate, br"},
  {"accept-language", "en-GB,en;q=0.9,fr;q=0.8"},
  {"cache-control", "max-age=0"},
  {"connection", "keep-alive"},
  {"cookie",
   "_xsrf=2|353a732a|e6f0e245b4f4617b78f5080f716b5a83|1548858283; username-localhost-8888=\"2|1:0|10:1548926887|23:username-localhost-8888|44:MjlmNjg1MmMwMTA5NGZlNjllM2FmNzg0YmFlMDM4ZTY=|b5777f2478a76e40e5d2a194c35a6dc49771b5522513299099e9baf47d7c0975\"; _shortr_key=SFMyNTY.g3QAAAABbQAAAAtfY3NyZl90b2tlbm0AAAAYcnEvMWJQRE1OSVROSG1JOXRDY1VrUT09.SAlNvN6U9ol3ldsUP2qjlVXTJgvtLdSUzjBkAuuW5NM"},
  {"host", "localhost:4000"},
  {"referer", "http://localhost:4000/links"},
  {"upgrade-insecure-requests", "1"},
  {"user-agent",
   "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.81 Safari/537.36"}
]

我需要将其转换为 Map（发送到 ecto），这样 %{"accept" => "...", ...}

在 python 中我会做类似的事情

{v[0]: v[1] for v in original_list}

Elixir 有这么美的东西吗？

【问题讨论】：

标签： elixir phoenix-framework

【解决方案1】：

使用Enum#into/2:

将给定的 enumerable 插入可收集的对象中。

例如（有关更多示例，请参阅文档）：

iex> [{"foo", "bar"}, {"fizz"}, {"buzz"}] |> Enum.into(%{})
%{"foo" => "bar", "fizz" => "buzz"}

在你的情况下：

iex(1)> [             
...(1)>   {"accept",
...(1)>    "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8"},
...(1)>   {"accept-encoding", "gzip, deflate, br"},
...(1)>   {"accept-language", "en-GB,en;q=0.9,fr;q=0.8"},
...(1)>   {"cache-control", "max-age=0"},
...(1)>   {"connection", "keep-alive"},
...(1)>   {"cookie",
...(1)>    "_xsrf=2|353a732a|e6f0e245b4f4617b78f5080f716b5a83|1548858283; username-localhost-8888=\"2|1:0|10:1548926887|23:username-localhost-8888|44:MjlmNjg1MmMwMTA5NGZlNjllM2FmNzg0YmFlMDM4ZTY=|b5777f2478a76e40e5d2a194c35a6dc49771b5522513299099e9baf47d7c0975\"; _shortr_key=SFMyNTY.g3QAAAABbQAAAAtfY3NyZl90b2tlbm0AAAAYcnEvMWJQRE1OSVROSG1JOXRDY1VrUT09.SAlNvN6U9ol3ldsUP2qjlVXTJgvtLdSUzjBkAuuW5NM"},
...(1)>   {"host", "localhost:4000"},
...(1)>   {"referer", "http://localhost:4000/links"},
...(1)>   {"upgrade-insecure-requests", "1"},
...(1)>   {"user-agent",
...(1)>    "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.81 Safari/537.36"}
...(1)> ] |> Enum.into(%{})
%{
  "accept" => "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
  "accept-encoding" => "gzip, deflate, br",
  "accept-language" => "en-GB,en;q=0.9,fr;q=0.8",
  "cache-control" => "max-age=0",
  "connection" => "keep-alive",
  "cookie" => "_xsrf=2|353a732a|e6f0e245b4f4617b78f5080f716b5a83|1548858283; username-localhost-8888=\"2|1:0|10:1548926887|23:username-localhost-8888|44:MjlmNjg1MmMwMTA5NGZlNjllM2FmNzg0YmFlMDM4ZTY=|b5777f2478a76e40e5d2a194c35a6dc49771b5522513299099e9baf47d7c0975\"; _shortr_key=SFMyNTY.g3QAAAABbQAAAAtfY3NyZl90b2tlbm0AAAAYcnEvMWJQRE1OSVROSG1JOXRDY1VrUT09.SAlNvN6U9ol3ldsUP2qjlVXTJgvtLdSUzjBkAuuW5NM",
  "host" => "localhost:4000",
  "referer" => "http://localhost:4000/links",
  "upgrade-insecure-requests" => "1",
  "user-agent" => "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.81 Safari/537.36"
}

【讨论】：

【解决方案2】：

你也可以使用Map.new

https://hexdocs.pm/elixir/Map.html#new/1

iex> [{"foo", "bar"}, {"fizz", "buzz"}] |> Map.new
%{"fizz" => "buzz", "foo" => "bar"}

【讨论】：