Category Archives: Phoenix

Erlang and Elixir with asdf in Raspberry 4 with Ubuntu 20.04

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To install the latest/current versions of erlang (23.0.2) and elixir (1.10.3), follow the instructions below:

Install asdf ( full instructions https://asdf-vm.com/#/core-manage-asdf-vm):

SHELL

Add the following two lines in your ~/.bashrc file:

SHELL

Reload/Source your bash file with

SHELL

Install the erlang plugin

SHELL

If you get the following warnings:

SHELL

Install the missing packages:

SHELL

Install latest erlang version:

SHELL

Set it up globally (if you want):

SHELL

Add elixir plugin:

SHELL

Install latest elixir version (1.10.3):

SHELL

Set it up globally:

SHELL

Finally you can also install the latest Phoenix version (1.5.3):

SHELL

Using a primary key not named id with Ecto and Mysql

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Problem

You would like to use a legacy or a database you don’t have control over, with Phoenix, but the primary key of the table it is not named ‘id’.

** (Mariaex.Error) (1054): Unknown column 'p0.id' in 'field list'

Solution

You can define the primary key using the @primary_key as in:

 @primary_key {:id_other_name, :integer, []}
  schema "db_table" do
    field :description, :string
    ...
  end

Taken from here

Starting Phoenix server in a different port than 4000

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Problem

You would like start a phoenix application in a port different from the default 4000, by using something similar to the rails:

rails s -p 4001

Solutin

You will need to change the config/dev.exs file to include the following:

http: [port: System.get_env("PORT") || 4000],

and then start the server with:

PORT=4002 mix phoenix.server

Taken from the answer here

Request failed (404) ** (Mix) Package fetch failed and no cached copy available

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Problem

You are trying to use hex for installing dependencies but when you are behind a proxy you get the following message:

Request failed (404)
** (Mix) Package fetch failed and no cached copy available

Solution

You can use the following to set up hex (taken from the answer here:

mix hex.config http_proxy http://proxy.mycompany.com

Error: Brunch 2+ requires node v4.0+. Upgrade node or use older brunch for old node.js: npm i -g brunch@1

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Problem

Trying to start a new phoenix application while your node installation is old you get the following error:

Error: Brunch 2+ requires node v4.0+. Upgrade node or use older brunch for old node.js: npm i -g brunch@1 -g brunch@1

Solution

You will need to upgrade your node installation by following the steps below:

$> node -v
v0.10.32
$> sudo yum install nodejs npm (if npm is not available)
$> npm cache clean -f
$> npm install -g n
$> sudo /path/n/was/installed(ie /home/kosmas/bin/n) stable
$> node -v
v5.10.1

Updating Phoenix from 0.3.1 to 0.4.0

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Problem

You would like to upgrade to the latest version of Phoenix 0.4.0 from the previous version of 0.3.1. When you try to update the dependencies and try to start phoenix again (mix phoenix.start) you get the following error:

** (Mix) You're trying to run :your_app_name on Elixir v1.0.0-rc1 
but it has declared in its mix.exs file it supports 
only Elixir ~> 0.15.0

Solution

After upgrading your Elixir version to the latest (1.0.0-rc1), and updating the path to your elixir installation so that it uses the new one, clear the dependencies from your project:

mix deps.clear --all

Change the dependency in your mix.exs file to be as the following:

def project do
    [ app: :your_app_name,
      version: "0.0.1",
      elixir: "~> 1.0.0-rc1",
      elixirc_paths: ["lib", "web"],
      deps: deps ]
  end

and then get the dependencies again with:

mix deps.get

after that you should be able to start your phoenix project with tne new version.