Legacy wrapper with rjson/RJSONIO behaviour

[jeroen]

Many people that come from rjson or RJSONIO have complained about the different defaults. Maybe we should add a legacy wrapper to jsonlite that uses similar defaults as RJSONIO (but without the bugs).

• auto_unbox = true
• dataframe = "column"
• na = "null"
• null = "null"
• use_signif = true

That might make it easier for people to migrate. I think shiny does something similar internally. Perhaps this could also address #71 and r-lib/httr#187.

[hadley]

I was thinking it might be use to have a few variants:

• rjson/RJSONIO legacy flavour
• API flavour, auto_unbox = TRUE and dataframe = "column"

[jeroen]

See also rstudio/shiny#767.

[wch]

I think the command would now be something like:

# RJSONIO compatibility wrapper
toJSON2 <- function(x, ...) {
  jsonlite::toJSON(I(x), dataframe = "columns", null = "null", na = "null",
                   auto_unbox = TRUE, use_signif = TRUE, force = TRUE,
                   rownames = FALSE, keep_vec_names = TRUE, ...)
}

[jeroen]

You need to specify the arguments in toJSON2 header otherwise they get set twice if the user does e.g. toJSON2(x, dataframe="row")

[wch]

Oh, right, thanks.

It turns out there's also an incompatible change with time conversion: rstudio/shiny#773.

[hadley]

Maybe toApiJSON would be a nice name?

[jeroen]

I'm not sure I want to promote the RJSONIO legacy behavior as optimal for apis. The keep_vec_names = TRUE option is dangerous and unnecessary and most API's that I have worked with prefer dataframe="rows".

[hadley]

The auto boxing behaviour is super annoying - I don't care about anything else

[jeroen]

Yes I am aware of that. But we should think the other defaults through as well if we want to get it right this time.

[wch]

OK, so the updated function for compatibility would look like:

toJSON2 <- function(x, dataframe = "columns", null = "null", na = "null",
  auto_unbox = TRUE, use_signif = TRUE, force = TRUE, rownames = FALSE,
  POSIXt = "epoch", keep_vec_names = TRUE, ...) {

  jsonlite::toJSON(I(x), dataframe = dataframe, null = null, na = na,
    auto_unbox = auto_unbox, use_signif = use_signif, force = force,
    rownames = rownames, POSIXt = POSIXt, keep_vec_names = keep_vec_names, ...)
}

But for Shiny, it looks we're going to diverge from full RJSONIO compatibility a bit. Instead of POSIXt="epoch", we're probably going to do POSIXt="ISO8601", UTC = TRUE.