R: flatten a JSON file into a data frame

dataframeFromJSON

## Example data.json
[{"event":"glop","params":{"name":"toto","value":"glop"}},
{"event":"glot","params":{"name":"toto","info":"gggg"}},
{"event":"gogo","params":"text"},
{"event":"gogo2"}
];

## Expected output
  event params.name params.value params.info params
1  glop        toto         glop        <NA>   <NA>
2  glot        toto         <NA>        gggg   <NA>
3  gogo        <NA>         <NA>        <NA>   text
4 gogo2        <NA>         <NA>        <NA>   <NA>

## Flattening function
dataframeFromJSON <- function(l) {
  l1 <- lapply(l, function(x) {
    x[sapply(x, is.null)] <- NA
    unlist(x)
  })
  keys <- unique(unlist(lapply(l1, names)))
  l2 <- lapply(l1, '[', keys)
  l3 <- lapply(l2, setNames, keys)
  res <- data.frame(do.call(rbind, l3))
  return(res)
}
## Example
data <- fromJSON(paste(readLines('data.json'), collapse=""))
df <- dataframeFromJSON(data)