r - カスタム更新***入力関数からShiny::toJSON引数を設定する方法は?

Question

Shinyのカスタム入力バインディングを開発しています。data.table私はjavascriptに渡すことを持っています。残念ながら、データは列単位ではなく行単位でエンコードする必要があります。 private$inputMessageQueue追加の引数shiny::toJSONなしで処理されるため、デフォルトの引数をオーバーライドする場所はありません。必要なフォーマットを取得するにはどうすればよいですか?

data.tablemy (as message$data)を受け取る Shiny 関数

debugging in: session$sendInputMessage(inputId, message)
debug: {
    data <- list(id = inputId, message = message)
    private$inputMessageQueue[[length(private$inputMessageQueue) + 
        1]] <- data
}

私の構造data.table：

Browse[4]> str(message$data)
Classes ‘data.table’ and 'data.frame':  8 obs. of  7 variables:
 $ coOrdinate       : chr  "c1" "c2" "c3" "c4" ...
 $ injectionSite    : Factor w/ 2 levels "head","body": NA NA NA NA NA NA NA NA
 $ drug             : Factor w/ 2 levels "aconitin","nicotine": NA NA NA NA NA NA NA NA
 $ drugConcentration: num  NA NA NA NA NA NA NA NA
 $ bath             : Factor w/ 2 levels "aconitin","nicotine": NA NA NA NA NA NA NA NA
 $ bathConcentration: num  NA NA NA NA NA NA NA NA
 $ status           : Factor w/ 3 levels "active","dead",..: 1 1 1 1 1 1 1 1
 - attr(*, ".internal.selfref")=<externalptr> 

私の実際のデータdata.table:

Browse[4]> message$data
   coOrdinate injectionSite drug drugConcentration bath bathConcentration status
1:         c1            NA   NA                NA   NA                NA active
2:         c2            NA   NA                NA   NA                NA active
3:         c3            NA   NA                NA   NA                NA active
4:         c4            NA   NA                NA   NA                NA active
5:         c5            NA   NA                NA   NA                NA active
6:         c6            NA   NA                NA   NA                NA active
7:         c7            NA   NA                NA   NA                NA active
8:         c8            NA   NA                NA   NA                NA active

シャイニーにやりたいこと：

Browse[4]> jsonlite::toJSON(message$data)

[
    {"coOrdinate":"c1","status":"active"},
    {"coOrdinate":"c2","status":"active"},
    {"coOrdinate":"c3","status":"active"},
    {"coOrdinate":"c4","status":"active"},
    {"coOrdinate":"c5","status":"active"},
    {"coOrdinate":"c6","status":"active"},
    {"coOrdinate":"c7","status":"active"},
    {"coOrdinate":"c8","status":"active"}
] 

private$InputMessageQueue が処理されたときの Shiny の動作 ( shiny.Rにある)

jsonlite::toJSON(I(message$data),dataframe='columns',null='null', na='null', auto_unbox=T, force=T, rownames=F, keep_vec_name=T)

{
    "coOrdinate":["c1","c2","c3","c4","c5","c6","c7","c8"],
    "injectionSite":[null,null,null,null,null,null,null,null],
    "drug":[null,null,null,null,null,null,null,null],
    "drugConcentration":[null,null,null,null,null,null,null,null],
    "bath":[null,null,null,null,null,null,null,null],
    "bathConcentration":[null,null,null,null,null,null,null,null],
    "status":["active","active","active","active","active","active","active","active"]
}

他のすべてが失敗した場合は、data.table をマトリックスにキャストできます。これにより、行単位の JSON が得られますが、列名が失われます。

Browse[4]> jsonlite::toJSON(I(as.matrix(message$data)),dataframe='columns',null='null', na='null', auto_unbox=T, force=T, rownames=F, keep_vec_name=T)

[
    ["c1",null,null,null,null,null,"active"],
    ["c2",null,null,null,null,null,"active"],
    ["c3",null,null,null,null,null,"active"],
    ["c4",null,null,null,null,null,"active"],
    ["c5",null,null,null,null,null,"active"],
    ["c6",null,null,null,null,null,"active"],
    ["c7",null,null,null,null,null,"active"],
    ["c8",null,null,null,null,null,"active"]
] 

では、Shiny に data.frame を行ごとに渡すように強制するにはどうすればよいでしょうか?