r-json-and-set-list-elements-to-null.R

library(tidyverse)
library(jsonlite)
#> 
#> Attaching package: 'jsonlite'
#> The following object is masked from 'package:purrr':
#> 
#>     flatten

# Ref: https://stackoverflow.com/questions/7944809/assigning-null-to-a-list-element-in-r

# JSON with 'null' keyword gets a null when cast to list object.
json_with_null <- '{"a": 1, "b": "B", "c": null}'
json_with_null %>% fromJSON()
#> $a
#> [1] 1
#> 
#> $b
#> [1] "B"
#> 
#> $c
#> NULL


# This works as well
lstt <- list(a=1, b="B", c=NULL)
str(lstt)
#> List of 3
#>  $ a: num 1
#>  $ b: chr "B"
#>  $ c: NULL

# ! Does not work, removes whole entry
lstt[["c"]] <- NULL
str(lstt)
#> List of 2
#>  $ a: num 1
#>  $ b: chr "B"

# This however does NOT QUITE work
lstt[["c"]] <- list(NULL)
str(lstt)
#> List of 3
#>  $ a: num 1
#>  $ b: chr "B"
#>  $ c:List of 1
#>   ..$ : NULL


# This does...
lstt["c"] <- list(NULL)
str(lstt)
#> List of 3
#>  $ a: num 1
#>  $ b: chr "B"
#>  $ c: NULL

# Created on 2018-09-06 by the [reprex package](http://reprex.tidyverse.org) (v0.2.0).