Make it easier to install?

[dbenamy]

I'm new to elixir and I'm having some trouble getting postgrex & ecto installed.

I brew installed elixir 0.13.0. It looks to me like the latest postgrex depends on a dev version of elixir. I found an older revision (7bb042d) and put that in my mix.exs and then I'm able to install it with "mix deps.update postgrex", but I can't compile because ecto wants a newer version of postgrex. I browsed through the ecto history a bit but it wasn't clear to me what revision to use.

Is there any easy way to do this without installing a dev version of elixir?

Thanks very much!

[josevalim]

Hey @dbenamy, we are sorry about that. We released postgrex depending on elixir-dev by accident and that is what is causing pain.

Please try using this commit: ec804cb

[dbenamy]

Thanks for the quick reply!

I changed my mix.exs to have

  defp deps do
    [
      {:phoenix, github: "phoenixframework/phoenix"},
      {:postgrex, "0.4.2", github: "ericmj/postgrex", tag: "ec804cb"}, # this revision works with elixir 0.13.0
      {:ecto, github: "elixir-lang/ecto"}
    ]
  end

ran

mix deps.clean --all
mix deps.get
mix deps.update postgrex

which gave normal looking output, and then

mix compile
Unchecked dependencies for environment dev:
* postgrex (git://github.com/ericmj/postgrex.git)
  the dependency postgrex in mix.exs is overriding a child dependency:

  > In mix.exs:
    {:postgrex, "0.4.2", [git: "git://github.com/ericmj/postgrex.git", tag: "ec804cb"]}

  > In deps/ecto/mix.exs:
    {:postgrex, "~> 0.4.0", [git: "git://github.com/ericmj/postgrex.git", optional: true]}

  Ensure they match or specify one of the above in your Statman.Mixfile deps and set `override: true`
** (Mix) Can't continue due to errors on dependencies

Am I missing something?

[ericmj]

You need to add override: true, like this: {:postgrex, "0.4.2", github: "ericmj/postgrex", tag: "ec804cb", override: true}.

[dbenamy]

That did it, thanks!!

Why does the override setting exist? If the version and/or tag are given, I would think that it's clear what the dev wants. But I'm really new at all this so I'm probably missing some important piece :-)

[josevalim]

@dbenamy the override exists because you may accidentally replace a dependency specified below. The override is to make sure you are defining it exactly because you want to override something.

[dbenamy]

Got it. Thanks for the explanation.

Want me to take a stab at a patch which updates the error message to
explain this and how to solve it?

On Thu, Apr 24, 2014 at 12:21 PM, José Valim notifications@github.comwrote:

@dbenamy https://github.com/dbenamy the override exists because you may
accidentally replace a dependency specified below. The override is to make
sure you are defining it exactly because you want to override something.

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/12#issuecomment-41300389
.

[ericmj]

@dbenamy The error message already includes the solution. From what you pasted: "Ensure they match or specify one of the above in your Statman.Mixfile deps and set override: true".

Do you think it should be more clear?

[dbenamy]

Oh :-) Now that I read it more carefully, I totally understand what it's saying. Maybe I was too new to elixir or too tired to process it at the time.

If I was going to rewrite the message though, I might have it say something like this

$ mix compile
** (Mix) Can't continue due to errors on dependencies
"projdir/mix.exs" has this dependency:
    {:postgrex, "0.4.2", [git: "git://github.com/ericmj/postgrex.git", tag: "ec804cb"]}
which conflicts with another dependency in "projdir/deps/ecto/mix.exs":
    {:postgrex, "~> 0.4.0", [git: "git://github.com/ericmj/postgrex.git", optional: true]}

Normally, you should change "projdir/mix.exs" to specify the same version as ecto, for example:
    {:postgrex, "~> 0.4.0", [git: "git://github.com/ericmj/postgrex.git"]}
If you really want to use the version in "projdir/mix.exs", add the override setting like this:
    {:postgrex, "0.4.2", [git: "git://github.com/ericmj/postgrex.git", tag: "ec804cb", override: true]}

But it's probably not too important.