Batch paste to an api using post in R - r

Question

Im trying to paste multiple vin numbers to the nthsa API.
My working solution looks like this:
vins <- c('4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466','4JGCB5HE1CA138466',)
for (i in vins){
json <- fromJSON(paste0('https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVinValues/',i,'?format=json'))
print(json)
}
This solution is very slow. I tried pbapply, same thing because it pastes one vin at a time.
There is a batch paste option that i just cant figure out. Can someone please assist.
Here is my code so far:
data <- list(data='4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466')
json <- toJSON(list(data=data), auto_unbox = TRUE)
result <- POST('https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVINValuesBatch/', body = data)
Output <- content(result)
The vin numbers string has to be in the following format: vin;vin;vin;vin;
here is the link: https://vpic.nhtsa.dot.gov/api/ (the last one)
Thanks in advance.
UPDATE:
I also tried this from some other threads but no luck:
headers = c(
`Content-Type` = 'application/json'
)
data = '[{"data":"4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466"}]'
httr::POST(url = 'https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVINValuesBatch/', httr::add_headers(.headers=headers), body = data)
print(r$status_code)
I am getting status code 200 but server code 500 with no data.

Answer 1

I am not sure if this is possible. The batch endpoint is specifically looking for a dictionary to be passed (ruling out string representations). httr states:
body: must be NULL, FALSE, character, raw or list
I tried using collections library to generate dict
data <- Dict$new(list(format = 'json', data = "4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466"))
httr unsurprisingly rejected it as wrong body ype.
I tried using jsonlite to convert with:
data <- jsonlite::toJSON(data)
Yielding:
Error: No method asJSON S3 class: R6
I think due to data being an environment.
Trying to read in string dictionary to json returns no data:
library(httr)
library(jsonlite)
headers = c(
'Accept' = '*/*',
'Accept-Encoding' = 'gzip, deflate',
'Content-Type' = 'application/x-www-form-urlencoded',
'User-Agent' = 'Mozilla/5.0'
)
data = jsonlite::toJSON('{"format":"json","data":"4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466"}')
r<- httr::POST(url = 'https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVINValuesBatch/', httr::add_headers(.headers=headers), body = data. encode='json'
print(content(r))
If we examine converted data
> data
["{\"format\":\"json\",\"data\":\"4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466\"}"]
This is no longer the dictionary structure the server expects.
So, I am new to R but seems like it might be easier to just go with Python which has a dictionary object and also a json library which handles comfortably the conversion
string to json:
import requests,json
url = 'https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVINValuesBatch/'
data = json.loads('{"format": "json", "data":"4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466"}')
r = requests.post(url, data=data)
print(r.json())
dict
import requests
url = 'https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVINValuesBatch/'
data = {'format': 'json', 'data':'4JGCB5HE1CA138466;4JGCB5HE1CA138466;4JGCB5HE1CA138466'}
r = requests.post(url, data=data).json()
print(r)