elixir

How do you run middleware functions post response in Phoenix framework?

由 孤者浪人 提交于 2021-01-27 22:18:41
问题 I'm developing a simple website in Elixir with Phoenix. I'd like to add some custom middleware that runs after a response has been generated. For example, in order to log the total number of bytes in each response I'd like to have a Plug like this defmodule HelloWeb.Plugs.ByteLogger do import Plug.Conn require Logger def init(default), do: default def call(conn, default) do log("bytes sent: #{String.length(conn.resp_body)}") end end Trying to use this plug in one of the Phoenix pipelines in

elixir-lang Finding non-duplicate elements in a list

由 穿精又带淫゛_ 提交于 2021-01-26 10:00:28
问题 I'm trying to find non duplicate values from a list e.g. original list: iex> list = [2, 3, 4, 4, 5, 6, 6, 6, 7, 8, 8, 8, 9, 9, 10, 10, 10] [2, 3, 4, 4, 5, 6, 6, 6, 7, 8, 8, 8, 9, 9, 10, 10, 10] iex> unique = Enum.uniq(list) [2, 3, 4, 5, 6, 7, 8, 9, 10] iex> nondupes = unique -- Enum.uniq(list -- unique) [2, 3, 5, 7] result: [2, 3, 5, 7] I was wondering if there was a better way to achieve this in elixir/erlang 回答1: Another method (not necessarily better) that might be faster for large data is

Efficient way to filter a Map by value in Elixir

由 戏子无情 提交于 2021-01-18 05:26:25
问题 In Elixir, what would be an efficient way to filter a Map by its values. Right now I have the following solution %{foo: "bar", biz: nil, baz: 4} |> Enum.reject(fn {_, v} -> is_nil(v) end) |> Map.new This solution seems pretty inefficient to me. When called on a Map , Enum.reject/2 returns a Keywords . Since I want a Map , I need to call Map.new/1 to convert that Keywords back to me. This seems inefficient because Enum.reject/2 has to iterate over the Map once and then presumably, Map.new/1

Efficient way to filter a Map by value in Elixir

由 空扰寡人 提交于 2021-01-18 05:25:06
问题 In Elixir, what would be an efficient way to filter a Map by its values. Right now I have the following solution %{foo: "bar", biz: nil, baz: 4} |> Enum.reject(fn {_, v} -> is_nil(v) end) |> Map.new This solution seems pretty inefficient to me. When called on a Map , Enum.reject/2 returns a Keywords . Since I want a Map , I need to call Map.new/1 to convert that Keywords back to me. This seems inefficient because Enum.reject/2 has to iterate over the Map once and then presumably, Map.new/1

Java/Python/Elixir 正则库使用上的注意事项

由 穿精又带淫゛_ 提交于 2021-01-14 04:53:45
个人笔记，写得乱。。不过自己看得懂就行了—_— 日常工作中能接触到的正则，分为两大派别，其中 Unix-Like 系统中常用的正则，属于 POSIX “派”（较弱），而各编程语言标准库中的 Re，基本都是 PCRE “派”。（详见 正则表达式“派别”简述 ） 可虽然说各编程语言基本都属于 PCRE 派，实现上却还是各有特点，一个正则想在各语言间移植，也往往需要一番修改。 今天学 Elixir，就在正则上遇到了问题，百度一番，想想索性就把这些差别总结一遍，防止下次又掉坑里。（包括 Python、Java、Elixir、文本编辑器的正则，有时间把 SQL 的正则也写写。。） 一、正则库方法上的差别 1.1 模式匹配 文本编辑器的正则 是用来搜索的 ，会匹配 整段文本中所有符合该模式的字符串 ，可以叫做 find all 。 而不同的编程语言，又要看方法设计上的理念差别： Python 提供了以下方法 match：要求必须从字符串开头开始尝试匹配，相当与使用了 PCRE 的 anchored（锚定）模式。（或者说自动在正则开头添加了 \A ，它在 Python 中表示字符串开头） fullmatch：要求必须匹配整个字符串，相当于在正则的开头添加 \A ，末尾添加 \Z （它在 Python 中表示字符串末尾）. search：从字符串中搜索该模式，找到第一个就返回。 findall

【Phoenix】1、搭建 Phoenix 环境

由 半世苍凉 提交于 2021-01-09 02:54:07
Ps: 需要注意的是，我学习的时候，Elixir 是 1.8.1的版本，而 Phoenix 是 1.4.1的版本，对于其他版本，不一定正确。　 　 　　1、安装 Phoenix 之前，先安装 Elixir。 　　2、如果已经安装好了 Elixir ，使用一下命令安装 hex 这一个模块（为什么要安装 hex 我也不太懂，或许可以直接进行第三步）。 $ mix local.hex 　　3、安装好了 hex 使用下面的命令，安装 Phoenix。 $ mix archive. install hex phx_new 1.4 . 1 　　4、进行完上面的步骤，Phoenix 已经是安装好了。 　　5、Plug，Cowboy and Ecto 是 Phoenix 默认安装的依赖。 　　6、Phoenix 是默认使用 webpack 打包的，所以要安装 node.js，node.js 的版本 >= 5.0.0，Phoenix 安装 node.js 的教程是（如果你已经安装了 node.js 就不需要这一步的安装了） 　　　　（1）、install nodejs-legacy　　　　　　 $ apt-get install nodejs-legacy 　　　　 (2)、create a symlink (创建软连接，相当于 windows 的快捷方式) $ ln -s /usr/bin

Writing a clean/cleaner solution to “Valid Anagram” in Elixir

由 半腔热情 提交于 2021-01-07 06:36:38
问题 Trying to level up my Elixir understanding by doing algo/leetCode style problems using Elixir. As I'm a relatively new programmer (around a year in) and was trained on traditionally OOP languages like Ruby and JS, it's still somewhat hard for me to wrap my head around doing algo questions in a functional paradigm, though I felt I understood the Udemy course I took on Elixir/Phoenix. I wrote a solution to the LeetCode "valid anagram" problem using Elixir and Repl and wanted to see if people

Writing a clean/cleaner solution to “Valid Anagram” in Elixir

由 眉间皱痕 提交于 2021-01-07 06:35:31
问题 Trying to level up my Elixir understanding by doing algo/leetCode style problems using Elixir. As I'm a relatively new programmer (around a year in) and was trained on traditionally OOP languages like Ruby and JS, it's still somewhat hard for me to wrap my head around doing algo questions in a functional paradigm, though I felt I understood the Udemy course I took on Elixir/Phoenix. I wrote a solution to the LeetCode "valid anagram" problem using Elixir and Repl and wanted to see if people

Writing a clean/cleaner solution to “Valid Anagram” in Elixir

由 寵の児 提交于 2021-01-07 06:33:56
问题 Trying to level up my Elixir understanding by doing algo/leetCode style problems using Elixir. As I'm a relatively new programmer (around a year in) and was trained on traditionally OOP languages like Ruby and JS, it's still somewhat hard for me to wrap my head around doing algo questions in a functional paradigm, though I felt I understood the Udemy course I took on Elixir/Phoenix. I wrote a solution to the LeetCode "valid anagram" problem using Elixir and Repl and wanted to see if people

Nerves Project Circuits SPI Clock not initialised

由 我与影子孤独终老i 提交于 2021-01-05 07:23:07
问题 I cannot get the SPI to work. I am trying to interface an IC mcp2515. It is an SPI to CAN interface. I probed the CE pins (GPIO 8 and GPIO 7) and SCLK (GPIO 11) with the oscilloscope but got nothing. these are deps defp deps do [ {:nerves, "~> 1.6.3", runtime: false}, {:shoehorn, "~> 0.6.0"}, {:ring_logger, "~> 0.8.1"}, {:toolshed, "~> 0.2.13"}, {:vintage_net_wizard, "~> 0.4.0"}, {:circuits_uart, "~> 1.4"}, {:circuits_gpio, "~> 0.4.6"}, {:nerves_leds, "~> 0.8.1"}, {:circuits_spi, "~> 0.1.5"},
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