拨号器（通过 Dialyxir）从 Absinthe (GraphQL) 路由的 `forward` 命令发出有关“但此值不匹配”的警告。如何解决？

Posted 2023-03-08

【中文标题】拨号器（通过 Dialyxir）从 Absinthe (GraphQL) 路由的 `forward` 命令发出有关“但此值不匹配”的警告。如何解决？

【英文标题】：Dializer (via Dialyxir) warning about "but this value is unmatched" from `forward` command for Absinthe (GraphQL) route. How to address?

【发布时间】：2020-04-16 13:24:42

【问题描述】：

我收到关于不匹配返回的透析器错误，我不确定如何正确解决。

mix dialyzer --quiet
lib/my_app_web/router.ex:1:no_return
Function __checks__/0 has no local return.
________________________________________________________________________________
lib/my_app_web/router.ex:21:unmatched_return
The expression produces a value of type:

%
  :adapter => _,
  :before_send => _,
  :content_type => _,
  :context => _,
  :document_providers => _,
  :json_codec => _,
  :log_level => _,
  :no_query_message => _,
  :pipeline => _,
  :pubsub => _,
  :raw_options => Keyword.t(),
  :schema_mod => atom(),
  :serializer => _


but this value is unmatched.

________________________________________________________________________________
lib/my_app_web/router.ex:24:unmatched_return
The expression produces a value of type:

%
  :adapter => _,
  :additional_pipeline => _,
  :assets => _,
  :before_send => _,
  :content_type => _,
  :context => _,
  :default_headers => _,
  :default_url => _,
  :document_providers => _,
  :interface => _,
  :json_codec => _,
  :log_level => _,
  :no_query_message => _,
  :pipeline => Absinthe.Plug.GraphiQL, :pipeline,
  :pubsub => _,
  :raw_options => [_, _],
  :schema_mod => atom(),
  :serializer => _,
  :socket => _,
  :socket_url => _


but this value is unmatched.

我的mix.exs 看起来像这样：

  def project do
    [
      app: :my_app,
      version: "0.1.0",
      elixir: "1.9.4",
      elixirc_paths: elixirc_paths(Mix.env()),
      compilers: [:phoenix, :gettext] ++ Mix.compilers(),
      start_permanent: Mix.env() == :prod,
      dialyzer: [
        plt_add_deps: :transitive,
        flags: [:error_handling, :race_conditions, :unmatched_returns, :underspecs]
      ],
      aliases: aliases(),
      deps: deps()
    ]
  end

我的router.ex 看起来像这样：

defmodule MyAppWeb.Router do
  use MyAppWeb, :router

  pipeline :browser do
    plug :accepts, ["html"]
    plug :fetch_session
    plug :fetch_flash
    plug :protect_from_forgery
    plug :put_secure_browser_headers
    plug MyAppWeb.Auth
  end

  pipeline :api do
    plug :accepts, ["json"]
  end

  # Other scopes may use custom stacks.
  scope "/api" do
    pipe_through :api

    forward "/graphql", Absinthe.Plug, schema: MyAppWeb.Schema.UserTypes

    if Mix.env() == :dev do
      forward "/graphiql", Absinthe.Plug.GraphiQL,
        schema: MyAppWeb.Schema.UserTypes,
        interface: :simple
    end
  end

  scope "/", MyAppWeb do
    pipe_through :browser

    resources "/users", UserController,
      only: [:index, :show, :new, :create, :edit, :delete, :update]

    resources "/sessions", SessionController, only: [:new, :create, :delete]

    get "/", PageController, :index, as: :home

    get "/*path", PageController, :index
  end
end

我尝试了_ = 技巧，但它似乎不起作用。我认为使用无与伦比的回报可能会有所帮助，但在这种情况下可能不会。我已阅读此页面 (https://github.com/jeremyjh/dialyxir/wiki/Phoenix-Dialyxir-Quickstart)，但我认为它无助于解决此问题。

任何反馈或指导将不胜感激。

谢谢

【问题讨论】：

请将整个router.ex 发帖，以便我们检查dialyzer 提到的第1、21、24 行。

@AlekseiMatiushkin 我添加了整个路由器。第 21 和 24 行或 graphql 和 graphiql 行。

也就是说，dialyzer 不喜欢forwards。我从来没有用过 Absinth，但我会去检查他们的代码。

【参考方案1】：

我发现问题来自这个凤凰提交：https://github.com/phoenixframework/phoenix/commit/b10fb7dc33a198595872b783cbbf90f1daee91ba

可能是 Phoenix 问题或 Absinthe.Plug.init/1 规范导致警告。

在解决时间问题时，您可以使用 Dialyxir 的忽略警告功能：https://github.com/jeremyjh/dialyxir#ignore-warnings