Data module

[ghost]

Short hand api and specialized charts

[josevalim]

Here the Data example comes last, but in the previous example the Data example comes first. Should we make it consistent?

[josevalim]

There is an issue in this approach. This code only works because both x and color use "total". But if the color was encoded with another value, then its field would not be included in only. Thoughts?

[ghost]

Good catch! We rely on Table.Reader, so it might be better to remove the implicit only and allow passing it as an option of the data argument. Or maybe make it implicit by default and use the option to override it. 🤔

[josevalim]

I think we can have one option called additional_fields or something?

[ghost]

I prefer only for consistency, like in values_from

[ghost]

Data.chart([data: fuels, only: …], :point, x: "total", y: "solid_fuel")
And that should be the only argument accepted for data

[ghost]

Also, you said nothing about having or not a default…

[josevalim]

We should have a default, for sure. But I was wondering if we could have that as part of fields somehow:

Data.chart(fuels, :point, x: "total", y: "solid_fuel", additional_fields: [:foo, :bar])

Another idea is to move the logic VegaLite itself. We could support only: :lazy and then we compute it the time we build the JSON.

[josevalim]

Let's merge this without tackling this problem and please open up an issue so we do it next. :)

[ghost]

Ok!

[josevalim]

Some final nitpicks. We can handle the :only separately. :)