r - Using a JSON array in a POST request -

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• httr post request api returns 400 error 2 answers

i'm writing api wrapper query uk postcodes using httr package , works fine when use get requests. i'm lost when comes using post request.

here's documentation of api says:

accepts json object containing array of postcodes. returns list of matching postcodes , respective available data.

accepts 100 postcodes.

post https://api.postcodes.io/postcodes?q=[postcode]

post data

this method requires json object containing array of postcodes posted. e.g.

{ "postcodes" : ["pr3 0sg", "m45 6gn", "ex165bl"] }

i tried following:

library(httr)  pc_json <- '{   "postcodes" : ["pr3 0sg", "m45 6gn", "ex165bl"] }'  r <- post(paste0("https://api.postcodes.io/postcodes?q=", pc_json, encode = "json")) 

but returns this:

$status 1 400

$error 1 "invalid json submitted. need submit json object array of postcodes or geolocation objects"

the same happens when trim array , use this:

r <- post("https://api.postcodes.io/postcodes?q=ex165bl") content(r) 

i read similar threads here , here, didn't make problem easier solve.

any ideas how fix it?

your there need format postcodes list , use body argument of post encode json:

library(httr)  pc_json <- list(   postcodes = c("pr3 0sg", "m45 6gn", "ex165bl") ) res <- post("https://api.postcodes.io/postcodes"             , body = pc_json             , encode = "json") appdata <- content(res)