Fix up from_query docs

[cigrainger]

The examples for DataFrame.from_query show from_query/2, but this isn't defined. Params need to be passed, even if empty.

[josevalim]

At the time, we chose to require the parameters to avoid having two optional arguments that default to an empty list, which can be confusing.

Anyway, I am OK with merging this, your call!

[cigrainger]

Yeah I agree it can be confusing. Perhaps better to document it correctly instead of changing it? Or, could params just be an opt?

[josevalim]

👍 for improving the docs too!

[cigrainger]

Okay I've made params an opt and defaulted to [].

[josevalim]

Actually, I am not the biggest fan of this approach, sorry. :( Params are allegedly very common (or should be due for security), so I think it should be more first class than an option. Maybe we can do this:

@doc """
Shortcut for `query/4`.
"""
def query(conn, query, params_or_opts \\ []) when is_list(params_or_opts) do
  if Keyword.keyword?(params_or_opts) do
    query(conn, query, [], params_or_opts)
  else
    query(conn, query, params_or_opts, [])
  end
end

This way we can both as default but without the confusion? 🤔

[cigrainger]

Ah, I didn't know they should be encouraged. In that case, I think better to leave it as is but document it -- I'll do that.

[cigrainger]

😅 Okay there.