使用structs Elixir更新列表

map = %{
  shares: [%{name: "Junaid0"}]
}
add_shares = [%{name: "Junaid1"}, %{name: "Junaid2"}]

Straigt列表连接

%{map | shares: map[:shares] ++ add_shares}

%{map | shares: (for share <- add_shares, into: map[:shares], do: share)}

Enum.reduce

Enum.reduce(add_shares, map, fn share, acc ->
  %{acc | shares: [share | acc[:shares]]}
end)

Enum.into

%{map | shares: Enum.into(add_shares, map[:shares], & &1)}

FWIW:

将元素添加到现有列表中:

list = []
element = 42

list1 = [element | list]
#⇒ [42]
list2 = [element | list1]
#⇒ [42, 42]

Enum.reduce(email_array, {[], []}, fn
  email, {shares, changes} = _acc ->
    with {:found_user, sharee} <- ensure_user(email) do
      case :camera_share do
        {:ok, camera_share} ->
           {[camera_share | shares], changes}
        {:error, changeset} ->
           {shares, [changeset | changes]}
      end
    else
      # basically the same
      # make sure ALL branches return an acumulator
    end
  end)

上面的将返回一个元组 {shares, changes}

您可以创建如下简单方法:

def add_share(%{shares: shares} = map, share) do
  %{ map | shares: [share | shares] }
end

并调用它将项目添加到地图中的列表中:

%{shares: []}
|> add_share(%Cs{name: "Junaid1"})
|> add_share(%Cs{name: "Junaid2"})

结果:

%{shares: [%Cs{name: "Junaid2"}, %Cs{name: "Junaid1"}]}