如何从自定义更新***输入函数设置 Shiny::toJSON 参数？

Question

我正在开发一个 custom input binding for Shiny. I have a data.table that I am passing to a javascript. Unfortunately, the data needs to be encoded row-wise rather than column-wise. private$inputMessageQueue is processsed without extra arguments so there is no place to overrideshiny::toJSON 默认参数。我怎样才能得到我需要的格式？

接收我 data.table 的闪亮函数（如 message$data）

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

我的结构 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>

我的实际数据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

我希望 Shiny 做什么：

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"}
]

处理 private$InputMessageQueue 时 Shiny 做了什么（在 shiny.R 中找到）

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"]
}

如果一切都失败了，我可以将我的 data.table 转换为矩阵。这将按行显示 JSON，但我会丢失列名：

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"]
]

那么，我怎样才能强制 Shiny 按行传递我的 data.frame？

Answer 1

您可以简单地使用 jsonlite::toJSON() 对 R 数据进行预编码，然后将编码后的 JSON 字符串传递给 shiny。它将被视为逐字 JSON 字符串而不是双重编码（例如 "[1,2]" 将不会再次编码为 "\"[1,2]\""）。这是因为我们在 jsonlite::toJSON() (PR#795) 中使用了参数 json_verbatim = TRUE。这需要 shiny >= 0.12.0.

如何从自定义更新***输入函数设置 Shiny::toJSON 参数？

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