Support decompression in jsonlite::read_json

[dhimmel]

It's nice that jsonlite::read_json supports URLs for paths:

url = "https://github.com/related-sciences/nxontology-data/raw/71cf538dc5c258ada880d58663b0205b7b7f8561/087_chembl_target_tree.json"
jsonlite::read_json(path = url)

However, it doesn't appear to support URLs where the data is compressed:

url = "https://github.com/related-sciences/nxontology-data/raw/3330eb4ce4b29eb7399adb4e317a10a1c91138a7/mesh_topical_descriptor_descendants.json.gz"
jsonlite::read_json(path = url)  # fails

Would be nice to implement similar compression support to readr (docs):

Files ending in .gz, .bz2, .xz, or .zip will be automatically uncompressed.

And possibly adding a compression argument like pandas.read_json, such that users can override the inferred compression from the path.

[jeroen]

R has built-in compression tools so you can easily write a wrapper yourself.

read_compressed <- function(url){
  tmp <- tempfile()
  curl::curl_download(url, tmp)
  jsonlite::parse_json(gzfile(tmp))
}

url = "https://github.com/related-sciences/nxontology-data/raw/3330eb4ce4b29eb7399adb4e317a10a1c91138a7/mesh_topical_descriptor_descendants.json.gz"
read_compressed(url)

This also works:

url = "https://github.com/related-sciences/nxontology-data/raw/3330eb4ce4b29eb7399adb4e317a10a1c91138a7/mesh_topical_descriptor_descendants.json.gz"
jsonlite::parse_json(gzcon(url(url))) 

[dhimmel]

@jeroen much appreciate the code to read the gzipped URL data.

Is nice to have jsonlite abstract the compression handling, but understand if that's out of scope for the package.