Fetch the contents of a URL

Description

Low-level bindings to write data from a URL into memory, disk or a callback function. These are mainly intended for httr, most users will be better off using the curl or curl_download function, or the http specific wrappers in the httr package.

Usage

curl_fetch_memory(url, handle = new_handle())

curl_fetch_disk(url, path, handle = new_handle())

curl_fetch_stream(url, fun, handle = new_handle())

Arguments

Details

The curl_fetch functions automatically raise an error upon protocol problems (network, disk, ssl) but do not implement application logic. For example for you need to check the status code of http requests yourself in the response, and deal with it accordingly.

Both curl_fetch_memory and curl_fetch_disk have a blocking and non-blocking C implementation. The latter is slightly slower but allows for interrupting the download prematurely (using e.g. CTRL+C or ESC). Interrupting is enabled when R runs in interactive mode or when getOption("curl_interrupt") == TRUE.

Examples

# Load in memory
res <- curl_fetch_memory("http://httpbin.org/cookies/set?foo=123&bar=ftw")
res$content

# Save to disk
res <- curl_fetch_disk("http://httpbin.org/stream/10", tempfile())
res$content
readLines(res$content)

# Stream with callback
res <- curl_fetch_stream("http://httpbin.org/stream/20", function(x){
  cat(rawToChar(x))
})

Results