jsonlite::toJSON R- unbox json中的`[]`括号太多

Question

我目前正在构建一个api，它有几层信息。目前，我正在使用tibble并将信息嵌套在列下：

# A tibble: 1 x 3
  APICallTimeGMT      Error                some_data       
  <dttm>              <list>               <list>          
1 2018-10-19 11:43:10 <data.frame [1 × 2]> <tibble [2 × 3]>

然后，当我使用jsonlite::toJSON将其转换为JSON时，我得到了许多列表[]括号。有没有办法将这些特定的对象转换为json对象而不是列表。那么，嵌套对象应该是什么类(而不是data.frame)呢？

当前输出：

​

​

所需输出：

​

​

下面是可重复性的dput(x)：

structure(list(APICallTimeGMT = structure(1539949390.26164, class = c("POSIXct", 
"POSIXt")), Error = list(structure(list(msg = structure(1L, .Label = "OK", class = "factor"), 
    status = 200), .Names = c("msg", "status"), row.names = c(NA, 
-1L), class = "data.frame")), some_data = list(structure(list(
    Outcome = c("Case1", "Case2"), predictions = list(structure(list(
        ClassA = 0.4, ClassB = 0.1, ClassC = 0.5), .Names = c("ClassA", 
    "ClassB", "ClassC"), row.names = c(NA, -1L), class = "data.frame"), 
        structure(list(ClassA = 0.4, ClassB = 0.1, ClassC = 0.5), .Names = c("ClassA", 
        "ClassB", "ClassC"), row.names = c(NA, -1L), class = "data.frame")), 
    meta = list(structure(list(model = structure(1L, .Label = "Awesome AI", class = "factor"), 
        runs = 55), .Names = c("model", "runs"), row.names = c(NA, 
    -1L), class = "data.frame"), structure(list(model = structure(1L, .Label = "Awesome AI", class = "factor"), 
        runs = 55), .Names = c("model", "runs"), row.names = c(NA, 
    -1L), class = "data.frame"))), row.names = c(NA, -2L), class = c("tbl_df", 
"tbl", "data.frame"), .Names = c("Outcome", "predictions", "meta"
)))), row.names = c(NA, -1L), .Names = c("APICallTimeGMT", "Error", 
"some_data"), class = c("tbl_df", "tbl", "data.frame"))

Answer 1

Stéphane Laurent的回答很接近。看起来问题在于，如果数据在嵌套的碎石中，那么auto-unbox = TRUE就会以某种方式失败。为了正确打印上面的数据，我使用了mutate + purrr

library(jsonlite)

x_unboxed <- x %>% 
  mutate(Error = map(Error, ~.x %>% unbox),
         some_data = map(some_data, ~.x %>% 
                           mutate(predictions = map(predictions, ~.x %>% unbox),
                                  meta = map(meta, ~.x %>% unbox)))) %>% 
  unbox

x_unboxed %>% toJSON(., pretty = T)