我已经使用Elixir和Phoenix创建了JSON API
我在控制器中有一个创建操作的终点，该示例将带有JSON数据，看起来像这样：
[{"opens_detail"=>
[{"ua"=>"Linux/Ubuntu/Chrome/Chrome 28.0.1500.53",
"ip"=>"55.55.55.55",
"ts"=>1365190001,
"location"=>"Georgia, US"}],
"template"=>"example-template",
"metadata"=>{"user_id"=>"123", "website"=>"www.example.com"},
"clicks"=>42,
"ts"=>1365190000,
"state"=>"sent",
"clicks_detail"=>
[{"ua"=>"Linux/Ubuntu/Chrome/Chrome 28.0.1500.53",
"ip"=>"55.55.55.55",
"ts"=>1365190001,
"url"=>"http://www.example.com",
"location"=>"Georgia, US"}],
"email"=>"recipient.email@example.com",
"subject"=>"example subject",
"sender"=>"sender@example.com",
"_id"=>"abc123abc123abc123abc123",
"tags"=>["password-reset"],
"opens"=>42}]
我的目标是拿起这个JSON并从中创建一个新的，其中一些键和值重命名为以下示意图：
in Web/models/Messages.ex
...
schema "messages" do
field :sender, :string
field :uniq_id, :string # equal to '_id' in the payload
field :ts, :utc_datetime
field :template, :string
field :subject, :string
field :email, :string
field :tags, {:array, :string}
field :opens, :integer
field :opens_ip, :string # equal to nested 'ip' value in 'open_details'
field :opens_location, :string # equal to nested 'location' value in 'open_details'
field :clicks, :integer
field :clicks_ip, :string # equal to nested 'ip' value in 'click_details'
field :clicks_location, :string # equal to nested 'location' value in 'click_details'
field :status, :string # equal to the "state" in the payload
timestamps()
end
...
这是我尝试的：
in Web/Controller/Message_controller.ex ：
def create(conn, payload) do
%{ payload |
"uniq_id" => payload["_id"],
"status" => payload["type"]
"open_ips" => Enum.at(payload["opens_detail"], 0)['ip'],
"open_location" => Enum.at(payload["opens_detail"], 0)['location'],
"click_ips" => Enum.at(payload["clicks_detail"], 0)['ip'],
"click_location" => Enum.at(payload["clicks_detail"], 0)['location'],
}
changeset = Message.changeset(%Message{}, payload)
...
end
，但很快就很清楚它也行不通，因为我仍然需要删除一些钥匙。
我来自Ruby/Python(Rails/django(，不想开始污染我对功能编程的学习，特别是Elixir/Phoenix，借助我的知识。
您将如何解决此问题？
您将如何解决此问题？
我将创建一个从头开始的新地图，而不是更新原始地图。您可以使用get_in简化逻辑以访问嵌套字段。这是一个例子：
map = %{
uniq_id: get_in(payload, ["_id"]),
open_ips: get_in(payload, ["opens_detail", Access.at(0), "ip"]),
open_locations: get_in(payload, ["opens_detail", Access.at(0), "location"]),
}
如果要从原始地图中选择一部分字段，则可以使用Map.merge和Map.take：
Map.merge(Map.take(payload, [:sender, ...]), %{uniq_id: ...})
但是，如果只是几个字段，我宁愿手动写出它们。