Elixir：从嵌套列表中提取元素

我有以下JSON文件，其中包含一些混合数据

例如，我想从Facebook的

社交链接

链接

中提取

[
  [
    "social_links",
    [
      {
        "image":"http://example.com/icons/facebook.svg",
        "link":"https://www.facebook.com/Example",
        "alt":"Facebook"
      },
      {
        "image":"http://example.com/icons/twitter.svg",
        "link":"https://twitter.com/example",
        "alt":"Twitter"
      },
      {
        "image":"http://example.com/icons/linkedin.svg",
        "link":"https://www.linkedin.com/company/example",
        "alt":"Linkedin"
      },
      {
        "image":"http://example.com/icons/icons/rounded_googleplus.svg",
        "link":"https://plus.google.com/+example",
        "alt":"Google Plus"
      }
    ]
  ]
]

在Ruby中，我们可以使用以下代码从嵌套数据结构中获取数据：

hsh = JSON.parse str
hsh.select{ |k, _| k == "social_links" }[0][1].find { |k, _| k["alt"] == "Facebook"}["link"]
=> "https://www.facebook.com/Example"

---

如何在长生不老药中做同样的事情？从嵌套结构中提取数据的最佳做法是什么？

我将使用毒药进行解析：

[_, links] = Poison.decode!(json) |> Enum.find(&match?(["social_links" | _], &1))
link = Enum.find_value(links, fn %{"alt" => "Facebook", "link" => link} -> link end)

完整代码：

json = """
[
  [
    "social_links",
    [
      {
        "image":"http://example.com/icons/facebook.svg",
        "link":"https://www.facebook.com/Example",
        "alt":"Facebook"
      },
      {
        "image":"http://example.com/icons/twitter.svg",
        "link":"https://twitter.com/example",
        "alt":"Twitter"
      },
      {
        "image":"http://example.com/icons/linkedin.svg",
        "link":"https://www.linkedin.com/company/example",
        "alt":"Linkedin"
      },
      {
        "image":"http://example.com/icons/icons/rounded_googleplus.svg",
        "link":"https://plus.google.com/+example",
        "alt":"Google Plus"
      }
    ]
  ]
]
"""

[_, links] = Poison.decode!(json) |> Enum.find(&match?(["social_links" | _], &1))
link = Enum.find_value(links, fn %{"alt" => "Facebook", "link" => link} -> link end)
IO.puts link

输出：

https://www.facebook.com/Example

---

我会像这样使用毒药进行解析：

[_, links] = Poison.decode!(json) |> Enum.find(&match?(["social_links" | _], &1))
link = Enum.find_value(links, fn %{"alt" => "Facebook", "link" => link} -> link end)

完整代码：

json = """
[
  [
    "social_links",
    [
      {
        "image":"http://example.com/icons/facebook.svg",
        "link":"https://www.facebook.com/Example",
        "alt":"Facebook"
      },
      {
        "image":"http://example.com/icons/twitter.svg",
        "link":"https://twitter.com/example",
        "alt":"Twitter"
      },
      {
        "image":"http://example.com/icons/linkedin.svg",
        "link":"https://www.linkedin.com/company/example",
        "alt":"Linkedin"
      },
      {
        "image":"http://example.com/icons/icons/rounded_googleplus.svg",
        "link":"https://plus.google.com/+example",
        "alt":"Google Plus"
      }
    ]
  ]
]
"""

[_, links] = Poison.decode!(json) |> Enum.find(&match?(["social_links" | _], &1))
link = Enum.find_value(links, fn %{"alt" => "Facebook", "link" => link} -> link end)
IO.puts link

输出：

https://www.facebook.com/Example