用自定义值替换结构中的特定值

我会用 :maps.map/2 ,模式匹配值参数,并根据需要替换它:

new_unit =
  :maps.map(fn
    _, %Ecto.Association.NotLoaded{} -> "not loaded"
    _, value -> value
  end, unit)

Enum.map/2

因为结构只是映射,所以它们使用来自映射模块的函数

defmodule Test do
  defmodule User do
    defstruct name: "John", age: 27
  end

  def test() do
    a = %User{}
    IO.inspect a
    a = Map.put(a, :name, "change")
    IO.inspect a
  end

end

Test.test()

您可以尝试以下方法:

unit = %{
  __meta__: #Ecto.Schema.Metadata<:loaded, "units">,
  cdc_location_class_id: nil,
  description: "",
  facility: #Ecto.Association.NotLoaded<association :facility is not loaded>,
  facility_id: 2215,
  id: 719,
  is_active: true,
  name: "Unit",
  rooms: #Ecto.Association.NotLoaded<association :rooms is not loaded>
}

unit = case Ecto.assoc_loaded?(unit.facility) do
  false -> Map.put(unit, :facility, "not loaded")
  _ -> unit
end