presser_response: A presser response object

Description

presser creates a presser_response object for every incoming HTTP request. This object is passed to every matched route and middleware, until the HTTP response is sent. It has reference semantics, so handlers can modify it.

Arguments

Details

Fields and methods:

app: The presser_app object itself.
req: The request object.
headers_sent: Whether the response headers were already sent out.
locals: Local variables, the are shared between the handler functions. This is for the end user, and not for the middlewares.
delay(secs): delay the response for a number of seconds. If a handler calls delay(), the same handler will be called again, after the specified number of seconds have passed. Use the locals environment to distinguish between the calls. If you are using delay(), and want to serve requests in parallel, then you probably need a multi-threaded server, see server_opts().
add_header(field, value): Add a response header. Note that add_header() may create duplicate headers. You usually want set_header().
get_header(field): Query the currently set response headers. If field is not present it return NULL.
on_response(fun): Run the fun handler function just before the response is sent out. At this point the headers and the body are already properly set.
redirect(path, status = 302): Send a redirect response. It sets the Location header, and also sends a text/plain body.
render(view, locals = list()): Render a template page. Searches for the view template page, using all registered engine extensions, and calls the first matching template engine. Returns the filled template.
send(body). Send the specified body. body can be a raw vector, or HTML or other text. For raw vectors it sets the content type to application/octet-stream.
send_json(object = NULL, text = NULL, ...): Send a JSON response. Either object or text must be given. object will be converted to JSON using jsonlite::toJSON(). ... are passed to jsonlite::toJSON(). It sets the content type appropriately.
send_file(path, root = "."): Send a file. Set root = "/" for absolute file names. It sets the content type automatically, based on the extension of the file, if it is not set already.
send_status(status): Send the specified HTTP status code, without a response body.
send_chunk(data): Send a chunk of a response in chunked encoding. The first chunk will automatically send the HTTP response headers. Presser will automatically send a final zero-lengh chunk, unless $delay() is called.
set_header(field, value): Set a response header. If the headers have been sent out already, then it throws a warning, and does nothing.
set_status(status): Set the response status code. If the headers have been sent out already, then it throws a warning, and does nothing.
set_type(type): Set the response content type. If it contains a / character then it is set as is, otherwise it is assumed to be a file extension, and the corresponding MIME type is set. If the headers have been sent out already, then it throws a warning, and does nothing.
write(data): writes (part of) the body of the response. It also sends out the response headers, if they haven't been sent out before.

Usually you need one of the send() methods, to send out the HTTP response in one go, first the headers, then the body.

Alternatively, you can use $write() to send the response in parts.

Examples

Run this code

# NOT RUN {
# This is how you can see the request and response objects:
app <- new_app()
app$get("/", function(req, res) {
  browser()
  res$send("done")
})
app

# Now start this app on a port:
# app$listen(3000)
# and connect to it from a web browser: http://127.0.0.1:3000
# You can also use another R session to connect:
# httr::GET("http://127.0.0.1:3000")
# or the command line curl tool:
# curl -v http://127.0.0.1:3000
# The app will stop while processing the request.
# }

Run the code above in your browser using DataLab

Description

Arguments

Details

See Also

Examples