elixir

问题 I have made this genserver defmodule Recorder do use GenServer def start_link(args) do id = Map.get(args, :id) GenServer.start_link(__MODULE__, args, name: id) end def init(state) do schedule_fetch_call() {:ok, state} end def handle_info(:jpeg_fetch, state) do spawn(fn -> IO.inspect("I am being called") IO.inspect(DateTime.utc_now()) Fincher.request(:get, state.url) |> IO.inspect() end) schedule_fetch_call() {:noreply, Map.put(state, :run, true)} end defp schedule_fetch_call do Process.send

问题 In testing my Phoenix app, I keep running into situations where I'm comparing lists of expected versus actual record IDs. Errors are tedious to interpret because Elixir keeps printing the integer lists as charlists, so my test output looks like: Assertion with == failed code: assert H.sort(Enum.map(list1, &(&1.id()))) == H.sort(Enum.map(list2, &(&1.id()))) left: 'stu' right: 'st' This is nudging me to rewrite my tests to avoid comparing lists of integers, which is tolerable, but it's a shame

问题 I created an alternative phx.gen.html which creates templates with TailwindCSS. It works fine. I'd like to share it by creating a Hex package phx_tailwind_generators . Here is what I have so fare: $ phx_tailwind_generators:main> tree . ├── README.md ├── lib │ ├── phx_tailwind_generators.ex ├── mix.exs ├── priv │ └── templates │ └── tailwind.gen.html │ ├── controller.ex │ ├── controller_test.exs │ ├── edit.html.eex │ ├── form.html.eex │ ├── index.html.eex │ ├── new.html.eex │ ├── show.html.eex

问题 I'm building a Nerves project and am attempting to verify my custom firmware will be built with the main Nerves application following the instructions here. I've set up a UI project with Phoenix and have the custom image in its own directory under a project directory. The main Nerves project is here and the custom firmware is here I've set my MIX_TARGET equal to the custom image name (rpi0_wiringPi) and when running: mix deps.get I get the error * (ArgumentError) argument error :erlang.binary

问题 This question already has answers here : Elixir lists interpreted as char lists (3 answers) Closed last month . In Elixir, why does the comprehension for x <- 3..4, do: x * 2 result in [6, 8] but for x <- 3..4, do: x * 3 results in '\t\f' ? I'm executing this in the iex repl. 回答1: This is one of the most confusing gotchas in Elixir: the "humanizing" of charlists. See this post for a question revolving around this same issue. Charlists are lists of integer codepoints, used to represent un

问题 How would I go about finding if a sub-bitstring is present with another bitstring in Elixir? I need to verify that bitstring X exists somewhere within bitstring Y for testing purposes. Is there a simple way to do this with existing functions? x = "bar" y = "foo bar baz" some_substring_function(x, y) with some_substring_function returning a truthy value. Thanks in advance! 回答1: You can use the =~ operator: iex> "hello world" =~ "hello" true The String module also has some convenience functions

问题 I am compiling my application with mix compile and there an error is occurring for the dependency salty . I have already added the dependency salty and libsodium . But still error is not resolved. this is my mix.exs file with all the dependencies. defp deps do [ {:poison, "~> 3.0", override: true}, {:syndicate, in_umbrella: true}, {:xarango, "~> 0.7.0"}, {:ecto, "~> 3.1"}, {:phoenix, "~> 1.4.0"}, {:gettext, "~> 0.11"}, {:cowboy, "~> 2.6"}, {:joken, "~> 2.0"}, {:ecto_sql, "~> 3.0"}, {:jason, "

问题 I'm struggling to get this to work with Postgres and Ecto. The query below works fine without the group_by, but I need to group on the fragment field, which it can't seem to see. Any idea what's wrong with it? def query_clicks do from(Click) |> select( [c], [ fragment("date_trunc('hour',?) as hour", c.inserted_at), c.link_id] ) |> group_by([c], c.hour) |> Repo.all end Result: iex(1)> recompile; Shortr.LinkContext.query_clicks [debug] QUERY ERROR source="clicks" db=1.2ms queue=4.9ms SELECT

问题 I'm struggling to get this to work with Postgres and Ecto. The query below works fine without the group_by, but I need to group on the fragment field, which it can't seem to see. Any idea what's wrong with it? def query_clicks do from(Click) |> select( [c], [ fragment("date_trunc('hour',?) as hour", c.inserted_at), c.link_id] ) |> group_by([c], c.hour) |> Repo.all end Result: iex(1)> recompile; Shortr.LinkContext.query_clicks [debug] QUERY ERROR source="clicks" db=1.2ms queue=4.9ms SELECT

问题 I just changed an image path in a template in my Phoenix app and reloaded the page. This error message appeared in the browser: CompilationError at GET / Showing console output == Compilation error on file web/views/page_view.ex == ** (CompileError) web/views/page_view.ex:1: cannot define module Youli.PageView because it is currently being defined in web/views/page_view.ex:1 (stdlib) erl_eval.erl:657: :erl_eval.do_apply/6 Running mix compile in the terminal made the problem go away, but isn't