Data does not round trip through `writePreference()` and `readPreference()`

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
38/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
r
Domain
api

Research direction

Start by reproducing the reprex with rstudioapi::writePreference() and readPreference(), comparing the nested list structure with waldo::compare(). Trace how these functions serialize and reconstruct named lists. Done means a value written as a named list reads back with the same structure, without requiring the JSON-string workaround described in the issue.

Written by the indexing model from the issue text.

Description

Related to #247, I discovered that readPreference() does not preserve the structure of the value as it was provided to writePreference(). At a quick glance, the difference looks a lot like the data is being serialized as JSON but read with auto_unbox = FALSE.

Here's a small reprex list:

value_write <- list(
  fruit = "banana",
  drink = "coffee"
)

rstudioapi::writePreference("test", value_write)
value_read <- rstudioapi::readPreference("test", default = NULL)

waldo::compare(value_write, value_read)
#> `old$fruit` is a character vector ('banana')
#> `new$fruit` is a list
#> 
#> `old$drink` is a character vector ('coffee')
#> `new$drink` is a list

str(value_read)
#> List of 2
#>   $ fruit:List of 1
#>     ..$ : chr "banana"
#>   $ drink:List of 1
#>     ..$ : chr "coffee"

I thought I could handle serialization myself with jsonlite::serializeJSON(), but this led to #247.

value_write_json <- jsonlite::serializeJSON(value_write)
rstudioapi::writePreference("test", value_write_json)
#> Error in .rs.writePrefInternal("rs_writeApiPref", prefName, value) : 
#>   Type mismatch: expected <Object>; got <String>

I can safely roundtrip the data by serializing to a json string and storing in a named list, so I have a workaround, but it means a lot of boilerplate code to work around how the list is handled.

rstudioapi::writePreference("test", list(value = value_write_json))
# because of the first bit, we need $value[[1]] instead of just $value
value_read_json <- rstudioapi::readPreference("test", NULL)$value[[1]]
value_read_json <- jsonlite::unserializeJSON(value_read_json)

waldo::compare(value_write, value_read_json)
#> ✓ No differences
Session Info 
> rstudioapi::versionInfo()
$mode
[1] "desktop"

$version
[1] ‘2022.6.0.25’

$long_version
[1] "2022.06.0-daily+25"

$release_name
[1] "Spotted Wakerobin"

─ Session info ─────────────────────────────────────────────────────────────────────
 setting  value                       
 version  R version 3.6.3 (2020-02-29)
 os       OS X Snow Leopard 11.6.2    
 system   x86_64, darwin15.6.0        
 ui       RStudio                     
 language (EN)                        
 collate  en_US.UTF-8                 
 ctype    en_US.UTF-8                 
 tz       America/New_York            
 date     2022-01-28                  

─ Packages ─────────────────────────────────────────────────────────────────────────
 package    * version     date       lib source                             
 jsonlite     1.7.3       2022-01-17 [1] CRAN (R 3.6.3)                     
 rstudioapi   0.13.0-9000 2022-01-28 [1] Github (rstudio/rstudioapi@5d0f087)
Dominant language
R
Stars
175
Forks
37
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