Elixir:更新 map 列表

Question

假设我们有以下内容:

list = 
[
  %{"id" => 1, "name" => "Alice"},
  %{"id" => 2, "name" => "Bob"},
  %{"id" => 3, "name" => "Charlie"}
]

为了向每个元素添加具有值 person 的键 type，我们可以这样做:list |> Enum.map(fn x -> Map.put(x, "type", "person") end) 这将导致:

[
  %{"id" => 1, "name" => "Alice", "type" => "person"},
  %{"id" => 3, "name" => "Bob", "type" => "person"},
  %{"id" => 3, "name" => "Charlie", "type" => "person"}
]

现在，假设我们有另一个列表:

types = ["human", "alien", "unknown"]

如何组合list 和types 以便最终结果为:

[
  %{"id" => 1, "name" => "Alice", "type" => "human"},
  %{"id" => 2, "name" => "Bob", "type" => "alien"},
  %{"id" => 2, "name" => "Charlie", "type" => "unknown"}
]

?

Answer 1

使用 Enum.zip/2和 Enum.map/2应该做的伎俩:

list
|> Enum.zip(types)
|> Enum.map(fn {list, type} -> Map.put(list, "type", type) end)

[
  %{"id" => 1, "name" => "Alice", "type" => "human"},
  %{"id" => 2, "name" => "Bob", "type" => "alien"},
  %{"id" => 3, "name" => "Charlie", "type" => "unknown"}
]