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if_modified_since(request, options \\ [])

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Handles HTTP cache using if-modified-since header.

Only successful (200 OK) responses are cached.

This step also prepends a response step that loads and writes the cache. Be careful when prepending other response steps, make sure the cache is loaded/written as soon as possible.


  • :dir - the directory to store the cache, defaults to <user_cache_dir>/req (see: :filename.basedir/3)


iex> url = ""
iex> response = Req.get!(url, cache: true)
  status: 200,
  headers: [
    {"date", "Fri, 16 Apr 2021 10:09:56 GMT"},
iex> Req.get!(url, cache: true) == response