Mechanism to pull Kino.Input values into a module about kino

[josevalim]

Hi @davydog187! This is an Elixir behaviour, you can't access variables from "outside" inside functions. But you should be able to pass them inside by using a module attribute:

ExUnit.start()

defmodule SportFeed.Test do
  use ExUnit.Case
  @feed Kino.Input.textarea("feed")

  setup do
    %{data: Kino.Input.read(@feed)}
  end

  test "it works", %{data: data} do
    
  end
end

ExUnit.run()

You can also read the data before you store it.

[davydog187]

Thanks @josevalim. That was an approach I had tried, but you will get the following error

** (ArgumentError) cannot inject attribute @feed into function/macro because cannot escape #Reference<0.2064788886.4111204353.192084>. The supported values are: lists, tuples, maps, atoms, numbers, bitstrings, PIDs and remote functions in the format &Mod.fun/arity
    (elixir 1.13.0) lib/kernel.ex:3509: Kernel.do_at/5
    (elixir 1.13.0) expanding macro: Kernel.@/1
    feed_parser.livemd#cell:9: SportFeed.Test.__ex_unit_setup_0/1

[jonatanklosko]

@josevalim we could make the input reference a string, we already do that for the JS widgets, so it would be consistent (it's more of an id, but we use the word id for reevaluation safe id 🙈). WDYT?

[davydog187]

If that's a reasonable solution I can send a PR

[josevalim]

Sounds good to me! @jonatanklosko, how you want to generate the binary references?

[jonatanklosko]

I'd go with the same way we generate ids in Livebook, which is:

:crypto.strong_rand_bytes(20) |> Base.encode32(case: :lower)

I'll send a PR shortly, since there is probably a number of typespecs/docs to adjust too.

[jonatanklosko]

@davydog187 for the record here's a working example https://gist.github.com/jonatanklosko/2ce5865e361ff1a70e43b3dcc686c1fa :)

[davydog187]

great, thank you @jonatanklosko!

[BrooklinJazz]

Reading this over again (thank you a ton for doing this!)

I realized that @davydog187 and @jonatanklosko use a different methods for accessing the value from kino.

Dave put the Kino input in the module attribute.

defmodule SportFeed.Test do
  @feed Kino.Input.textarea("feed")
end

And Jonatan read the input in the module attribute.

feed = Kino.Input.textarea("feed")
defmodule SportFeed.Test do
  @feed Kino.Input.read(feed)
end

Wanted to clarify in case anyone tries to use the first option and it doesn't work.
I'm not sure if the second option did or did not work originally, but regardless thank you all!

[jonatanklosko]

@BrooklinJazz actually it's more like

# Cell 1
feed = Kino.Input.textarea("feed")
# [ Feed input ]

# Cell 2
defmodule SportFeed.Test do
  @feed feed

  # Then Kino.Input.read(feed) in tests
end

The point is that we need to render the input. We could also do @feed Kino.Input.textarea("feed") |> Kino.render(), but that's less obvious.

In practice reading the value as you mentioned totally does the job, because re-running the tests involves redefining the module anyway :)

[BrooklinJazz]

@jonatanklosko Woah! @feed Kino.Input.textarea("feed") |> Kino.render() totally works. That's really cool. This also helps me render multiple inputs so that's awesome.

Huge thank you 🙏