我有一个像这样的列表
[%{User: "1"}, %{User: "2"}]
使用后
HTTPoison.request(method, url, body, headers, option)
标题是
\"headers\":[{\"User\":\"1\"},{\"User_2\":\"2\"}]\r\n}
我希望有这样的结构
[{:user, "1"},{:user, "2"},{"content-type", "application/json"}]
添加偶数
{"content-type", "application/json"}
但我不明白如何在元组中转换我的数据(用户)
答案 0 :(得分:1)
目前还不是很清楚你想要改变什么以及如何改变。
假设您要将[%{User: "1"}, %{User: "2"}]
转换为[{user: "1"},{user: "2"}]
。
[%{User: "1"}, %{User: "2"}]
|> Enum.map(fn(item) -> {:user, item[:User]} end)
将产生
[user: "1", user: "2"]
结果等于[{:user, "1"},{:user, "2"}]
(关键字列表)。
答案 1 :(得分:1)
使用Kernel.SpecialForms.for/1
理解:
for %{User: id} <- [%{User: "1"}, %{User: "2"}], do: {:user, id}
#⇒ [user: "1", user: "2"]
请注意,[user: "1", user: "2"]
和[{:user, "1"}, {:user, "2"}]
完全相同。也就是说,两者都代表相同的元组列表(大小为2)。
添加新元组:只需将其添加到列表中:
[
{"content-type", "application/json"} |
(for %{User: id} <- [%{User: "1"}, %{User: "2"}], do: {:user, id})
]
#⇒ [{"content-type", "application/json"},
# {:user, "1"},
# {:user, "2"}]
或者,到最后(期望在将元素添加到列表末尾时的性能命中,最好如上所示进行前置,然后再List.reverse/1
):
users = for %{User: id} <- [%{User: "1"}, %{User: "2"}],
do: {:user, id}
users ++ [{"content-type", "application/json"}]
要将地图转换为相应的关键字列表(大小为2的元组),请使用Enum.flat_map/2
:
[%{foo: "1"}, %{baz: "2"}, %{bix: "3"}]
|> Enum.flat_map(&Map.to_list/1)
#⇒ [foo: "1", baz: "2", bix: "3"]
将密钥作为字符串:
[%{foo: "1"}, %{baz: "2"}, %{bix: "3"}]
|> Enum.flat_map(fn map ->
for {k, v} <- map, do: {Atom.to_string(k), v}
end)
#⇒ [{"foo", "1"}, {"baz", "2"}, {"bix", "3"}]