Create and replace mix.exs file

shahryarjb

Hi my friends, Imaging you have a mix file which you want to change part of it and replace after doing your changes.

For example

defmodule Dvote.MixProject do
  use Mix.Project

  def project do
    [  ..  ]
  end

  def application do
    [..... ]
  end

  defp elixirc_paths(:test), do: ["lib", "test/support"]
  defp elixirc_paths(_), do: ["lib"]

  defp deps do
    [
      {:phoenix, "~> 1.6.6"},
      {:mishka_installer, git: "https://github.com/mishka-group/mishka_installer.git"}
    ]
  end

  defp aliases do
    [.... ]
  end
end

Now I just want to change deps function and keep the other same as the orginal file and create a new mix.exs file.

  defp deps do
    [
      {:phoenix, "~> 1.6.6"},
      {:mishka_installer, git: "https://github.com/mishka-group/mishka_installer.git"},
      {:new_plug, "~> 1.0.0"}
    ]
  end

So I need suggestions how to do this! Regex? Or the other way, you can offer me?!
After creating this file in runtime!! So we need to compile whole the project because it is exs file? Or we can hot reload with a way?!

Why I need something like this?

I let my user add a dep from hex site in runtime, but I need to change the mix file auto with code and do not make user get involved to changing this file manually

By the way, I load my new deps from a json file

Thank you

The simple code for this: https://github.com/mishka-group/mishka_installer/blob/master/lib/installer/run_time_sourcing.ex

7 comments

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2022-05-16 08:21:24 UTC

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cmo

You’re completely mad

Post #1

shahryarjb

Thank you, I think it is going to help me to edit deps, and it is a good target to learn more about macro.

Why am I mad :)) ?

I will test it very soon.

Post #2

lud

Remember that your mix.exs file is code. That means that the deps function can return anything from anywhere, including using anything that is present in the erlang distribution like xmerl to read XML files for instance.

You could then define the dependencies in an xml file, which could allow more control of the data.

So you want to provide an app that can be added new dependencies to, at runtime? What is is exactly that you are trying to do? If the code added that way is not needed for the project to run then it is not an actual dependency ; maybe you need to implement a plugin solution for instance?

Post #3

shahryarjb

Hi dear @lud, I talked about this way I want to do in these post, I am open to receive any suggestion

and

in this video, you can see a simple demo

with these line I add a dep or delete it from my source
https://github.com/mishka-group/mishka_installer/blob/master/lib/installer/run_time_sourcing.ex#L10-L30

So, my user need to add his package into deps function and I create this for him/her

https://github.com/mishka-group/mishka_installer/blob/master/lib/installer/dep_handler.ex#L116-L127

So all the plugins are called from a JSON file which is created from my database

for example

  %MishkaInstaller.Installer.DepHandler{
    app: "mishka_social",
    version: "0.0.2 ",
    type: "hex",
    url: "https://hex.pm/packages/mishka_social",
    git_tag: nil,
    custom_command: nil,
    dependency_type: "force_update",
    update_server: nil,
    dependencies: [
      %{app: :phoenix, min: "1.6"},
      %{app: :phoenix_live_view, max: "0.17.7", min: "0.17.7"},
      %{app: :ueberauth, max: "0.17.7", min: "0.17.7"},
      %{app: :ueberauth_github, min: "0.8.1"},
      %{app: :ueberauth_google, min: "0.10.1"},
    ]
  }

So the only problem exist here that is keeping state when a dep was installed before. So my library let users register an event; before compiling I send a name of app and some information, if an app needs to save something, it prevents to force_update, if not it is going to be run the bottom function.

  # If you have a Task in your project you can load it in a list like [{:task_one, "ecto.migrate"}], it should be a list
  @spec deps(list()) :: list
  def deps(custom_command \\ []) when is_list(custom_command) do
    [{:get, "deps.get"}, {:compile, "deps.compile"}] ++ custom_command
    |> Enum.map(fn {operation, command} ->
      {stream, status} = System.cmd("mix", [command], into: IO.stream(), stderr_to_stdout: true)
      %{operation: operation, output: stream, status: status}
    end)
  end

In this function, when the lib gets an answer, it sends a pubsu to used admin dashboard

https://github.com/mishka-group/mishka_installer/blob/master/lib/installer/dep_changes_protector.ex#L83-L97

A simple dashboard I’m developing it: https://github.com/mishka-group/mishka_installer/blob/master/lib/installer/live/dep_getter.ex after that I add it in my CMS: GitHub - shahryarjb/mishka-cms: MishkaCms an open source and real time API base CMS Powered by Elixir and Phoenix · GitHub

My solution for event

https://github.com/mishka-group/mishka_installer

Post #4

lud

Ok so it looks like it is working, based on your demo.

I would still add special code to mix.exs to fetch deps from another file instead of modifying mix.exs itself. It can be an XML or it can be a binary file generater with :erlang.term_to_binary(new_deps).

create a new mix.exs file.

If you absolutely need to generate a new file then you can just change the path of the xml (or whatever format) in the mix.exs source. With the following code:

@xml_path "path/to/file.xml"

def deps do
    [
        {:a, "~> 1.2"},
        {:b, "~> 0.1.1"}
    ]
    ++ plugin_deps(@xml_path)
end

…a regex to update @xml_path "path/to/file.xml" is easy.

Post #5

shahryarjb

There is a problem, I did not test with xml, but with JSON, I can not call the function out of the mix file to convert JSON to list of tuples. Especially if you want to use a library, in exs file under a mix project like:
Mix.install([{:sourceror, github: "doorgan/sourceror"}]). And I call some essential information from my Genserver (on state), and mix file can not access to it.