Allow the baseUrl of elixir APIs to be overridden

[johannesE]

Elixir uses config.exs files to store most configuration values. This change allows the baseURL to be overridden with dev.exs and prod.exs in a project using the generated code.

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@mrmstn

[mrmstn]

Awesome, thank you very much for your contribution :D!

I've added a comment to your code, every thing else looks good to me 👍

(And I'm also quite unsure about my sugestion. I would simply add it for the sake of backwords compatibilty)

[mrmstn]

A little off-topic – but I'm currently making some extra changes in my connection.ex (which haven't found its way to this generator) so you might also be interested in something like this:

https://github.com/mrmstn/nomad_client/blob/main/lib/nomad_client/connection.ex

This solution is much more flexible since it allows you to use multiple URLs and also give some extra room to add some more middlewares or changing the adapter for the specific module. I'm very interested in some feedback about this practice.

Nonetheless, I'm a great fan of this PR :)!

[johannesE]

#12268 (comment)

Yes, that seems a lot more flexible and a little more complicated. Having the option to override the http adapter sounds great. We'd just need to document it with some examples and a link to the tesla configuration options. If you ever decide to give it a go for the main generator, I'll gladly check it out.

I'd probably change
config :tesla, NomadClient.Connection, ... to
config NomadClient.Connection, :tesla, ... though.

[wing328]

Tested locally and the result is good:

Generated openapi_petstore app
You have configured application :open_api_petstore in your configuration file,
but the application is not available.

This usually means one of:

  1. You have not added the application as a dependency in a mix.exs file.

  2. You are configuring an application that does not really exist.

Please ensure :open_api_petstore exists or remove the configuration.

...

Finished in 0.2 seconds (0.00s async, 0.2s sync)
3 tests, 0 failures

Randomized with seed 183352
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  11.087 s
[INFO] Finished at: 2022-05-01T15:48:27+08:00
[INFO] ------------------------------------------------------------------------

[halostatue]

@wing328 @mrmstn As I mentioned in #12751, there are changes that should be made to how the connection.ex is created, and the example provided by @mrmstn is very close to what I plan on doing as a future PR.