将地图转换为结构 [英] Convert maps to struct

问题描述

我正在尝试将地图转换为结构，如下所示：

I am trying to convert maps to struct as follow:

我有地图：

iex(6)> user                      
%{"basic_auth" => "Basic Ym1hOmphYnJhMTc=", "firstname" => "foo",
  "lastname" => "boo"}

该值应应用于struct：

The value should be applied to struct:

iex(7)> a = struct(UserInfo, user)
%SapOdataService.Auth.UserInfo{basic_auth: nil, firstname: nil, lastname: nil}

如您所见，struct的值为nil，为什么呢？

As you can see, the values of struct is nil, why?

推荐答案

到在JustMichael的答案上​​进行扩展，您可以先使用 String.to_existing_atom / 1 将键转换为原子，然后使用 Kernel.struct / 2 来构建结构：

To expand on JustMichael's answer, you can first convert the keys to atoms, using String.to_existing_atom/1, then Kernel.struct/2 to build the struct:

user_with_atom_keys = for {key, val} <- user, into: %{} do
  {String.to_existing_atom(key), val}
end

user_struct = struct(UserInfo, user_with_atom_keys)
# %UserInfo{basic_auth: "Basic Ym1hOmphYnJhMTc=", firstname: "foo",
 lastname: "boo"}

请注意，使用 String.to_existing_atom / 1 来防止VM达到全局Atom限制。

Note that this uses String.to_existing_atom/1 to prevent the VM from reaching the global Atom limit.

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