问题描述
我是Elixir和Phoenix的新手,所以这个问题可能很简单。我的Phoenix应用程序是一个API客户端,我正在尝试创建一个结构以对将从REST端点接收的数据进行建模。我基本上按照Poison GitHub页面上的小示例创建了我的模块:
defmodule Elixirserver.CurrentlyReprModule do
@derive [Poison.Encoder]
defstruct [:id,:time,:summary,:icon,:nearestStormdistance,:nearestStormbearing,:precipIntensity,:precipProbability,:temperature,:apparentTemperature,:dewPoint,:humidity,:pressure,:windSpeed,:windGust,:windbearing,:cloudCover,:uvIndex,:visibility,:ozone]
end
该模块位于lib/elixir_server/
下(这是否是此类文件的最佳位置?)。
(CompileError) lib/elixir_server/currently_repr_module.ex:2: module Poison.Encoder is not loaded and Could not be found
当我尝试运行iex -S mix
时,我收到类似的错误:
(UndefinedFunctionError) function Poison.Encoder.__using__/1 is undefined or private
解决方法
您的问题可能与项目的结构或从中调用命令的位置有关。这是从零到凤凰的示例,说明如何获取使用Jason
进行json编码的结构mix phx.new poison_demo --no-webpack --no-ecto
Fetch and install dependencies? [Yn] y
cd poison_demo
lib / poison_demo_web / router.ex
defmodule PoisonDemoWeb.Router do
use PoisonDemoWeb,:router
pipeline :api do
plug :accepts,["json"]
end
scope "/api",PoisonDemoWeb do
pipe_through :api
get "/repr",ReprController,:show
end
end
lib / poison_demo_web / controllers / repr_controller.ex
defmodule PoisonDemoWeb.ReprController do
use PoisonDemoWeb,:controller
def show(conn,_params) do
json(conn,%CurrentlyReprModule{})
end
end
lib / repr / repr.ex
defmodule CurrentlyReprModule do
@moduledoc false
@derive Jason.Encoder
defstruct [:id,:time,:summary,:icon,:nearestStormDistance,:nearestStormBearing,:precipIntensity,:precipProbability,:temperature,:apparentTemperature,:dewPoint,:humidity,:pressure,:windSpeed,:windGust,:windBearing,:cloudCover,:uvIndex,:visibility,:ozone]
end
iex -S mix phx.server
curl localhost:4000/api/repr
{"apparentTemperature":null,"cloudCover":null,"dewPoint":null,"humidity":null,"icon":null,"id":null,"nearestStormBearing":null,"nearestStormDistance":null,"ozone":null,"precipIntensity":null,"precipProbability":null,"pressure":null,"summary":null,"temperature":null,"time":null,"uvIndex":null,"visibility":null,"windBearing":null,"windGust":null,"windSpeed":null}
,
因此,事实证明我的问题是使用模块别名。这是我之前的elixir_server.ex
文件:
def repr_module do
quote do
use ElixirServer.CurrentlyReprModule
end
end
defmacro __using__(which) when is_atom(which) do
apply(__MODULE__,which,[])
end
在我alias
完成模块后:
def repr_module do
quote do
alias ElixirServer.CurrentlyReprModule,as: CurrentlyReprModule
end
end
defmacro __using__(which) when is_atom(which) do
apply(__MODULE__,[])
end
仍不确定为什么能解决Poison错误,但我们还是接受这些。