Automatically cast datetimes? about ex_machina HOT 12 CLOSED

I'll have to look into this more. Under the hood ExMachina uses changesets, so it might not be hard to also cast all the fields. I'm not totally sure ExMachina should handle this, but I'll think about it.

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Thank you :) I think dates/times in factories might be a bit painful otherwise – though maybe there's a nicer way than what I did.

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In the meantime you could simplify this by extracting a private function and calling Ecto.DateTime.cast

def factory(:package, _attrs) do
  %Package{
    hex_update_at: date_time("2001-02-03T04:05:06Z")
  }
end

defp date_time(date_time) do
  Ecto.DateTime.cast(date_time)
end

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@paulcsmith Good idea, thank you.

I'll sneak this in here since it's quite related: I'm unable to get this working for passed-in dates.

I tried this:

  def factory(:package, attrs) do
    time = Dict.get(attrs, :hex_updated_at, "2001-02-03T04:05:06Z")
    {:ok, cast_time} = Ecto.DateTime.cast(time)

    %Package{
      name: sequence(:name, &"package#{&1}"),
      description: "A package.",
      hex_updated_at: cast_time,
    }
  end

The default value is cast OK, but if I pass in a custom value, it is not cast. I debugged a bit and it seems the changes changeset that ExMachina.Ecto.save_record/3 gets does indeed not have the cast value. I guess I'm misunderstanding something about how you're meant to customize attributes if you also want to massage them a bit.

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@henrik Ah yes, that is a good point. The problem is that the cast attribute is overridden because the attrs are merged in after the factory/2 function is called. You can do what I said with a hard-coded binary, but if it's from the attrs it won't work unless you custom the save_record function to cast the changes with Ecto.Changeset.cast.

The more I think about it, the more it seems like this should be part of ExMachina.Ecto. I'll probably add it this week or next. Unless you want to try to tackle it in a PR :) I think it just needs to get the changes and pass them through Ecto.Changeset.cast.

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Oh yeah, I just found that part of the code. This bit, right?

  def build(module, factory_name, attrs \\ %{}) do
    attrs = Enum.into(attrs, %{})
    module.factory(factory_name, attrs) |> Map.merge(attrs)
  end

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I would love to tackle it in a PR, but I'm hard-pressed to find time for the project I'm actually trying to work on, so I don't think I'll have the time to spare until that's done :/ I'll customize save_record for now – good idea.

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No problem, I totally understand. Yes that's the bit that merges the parameters and overrides your cast one. Good luck with your project :)

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I started work on this, but it relies on elixir-ecto/ecto#1081 before I can get it working with associations. Once a new version of Ecto is released I can pick this work up again

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I'm going to check this when Ecto 2.0 comes out to see if it is handled automatically when you call Repo.insert!. That would be the most ideal solution, but if that doesn't work I'll try to come up with something else. I do agree that automatically casting would be a lot nicer. That way you can give it an erlang time from GoodTimes (as an example) and it would cast it correctly without having to do explicit conversion every time

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Chatted with @josevalim about this on IRC

[11:42:03] <paulcsmith_> josevalim Hmm, any ideas on how to handle this? #54 basically, it would be nice if you could set a datetime with an erlang datetime, but you have to manually cast it somewhere, either in the factory or when setting the attrs
[11:42:19] <paulcsmith_> And if you don't have time, no worries :)
[11:43:40] <paulcsmith_> Maybe I could cast everything and then call apply_changes before passing the record to Repo.insert. That's the first thing that comes to mind that might work. Not sure of the ramifications though
[11:44:31] paulcsmith_: i would say you should pass the proper value in
[11:44:45] paulcsmith_: datetime(....) when you call the factory
[11:44:49] paulcsmith_: won't hurt
[11:45:03] build(:package, inserted_at: datetime("...."))
[11:45:07] can even make it a sigil
[11:45:09] ~d(...)
[11:45:12] <paulcsmith_> Yeah that might be the best option. It's what I'm doing now and it does work :)
[11:45:24] <paulcsmith_> Oh the sigil idea sounds interesting. I'll have to try that out.
[11:45:27] <paulcsmith_> Thanks for the input :)

To sum up, the best option might be to add the datetime function as mentioned here to your factory, or add a sigil that does that for you. You'd probably want to make it a public function though so it could be used in your tests to override attributes: build(:package, inserted_at: datetime(GoodTimes.a_day_ago))

I'm considering adding a sigil to ExMachina.Ecto that you could optionally import, but it might be simple enough to just do on your own and we could add it to the README instead.

Does this help @henrik?

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I'm going to close this in favor of #94. Let me know if you have any further feedback on the other issue please :)

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