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Route handlers

Source: R/tidy_api.R
route_add.Rd

These functions helps you to add, remove, and retrieve route handlers. They all (except for route_get()) returns the route for easy chaining.

Usage

route_add(x, method, path, handler)

route_remove(x, method, path)

route_get(x, method, path)

Arguments

x

A Route object

method

A request method for the handler. The special method "all" will allow the handler to match all http request methods that comes in.

path

A URL path for the handler. See Paths for more on path semantics

handler

A handler function. See Handlers for more about the semantics of handlers

Value

x, modified. route_get() returns the requested handler

Paths

The path is a URL path consisting of strings, parameters (strings prefixed with :), and wildcards (*), separated by /. A wildcard will match anything and is thus not restricted to a single path element (i.e. it will span multiple / if possible). When serving a request only a single handler is selected based on the path match that is most specific. Specificity is based on number of path parts (ie. number of elements separated by /), the more the better; number of wildcards, the fewer the better; and number of keys, the fewer the better. When printing the route you can see the priority of all the paths in the route as they are sorted by that

Handlers

The handler is a function. At the very least it should have a ... argument and it must return eiter TRUE or FALSE. Returning TRUE means that the request is allowed to continue processing and can be passed on to the next route in the stack. Returning FALSE stops the processing of the request by the stack.

While any arguments besides ... are optional, there are a few that will get passed in named:

  • request will hold the request as a reqres::Request object

  • response will hold the request as a reqres::Response object

  • keys will be a named list containing the values of the matched path keys (see example)

Further, if routr is used as a fiery plugin, the handler will receive:

  • server is the fiery::Fire object defining the app

  • id is the id of the client sending the request, as provided by fiery

  • arg_list is a list of values as calculated by the servers before-request event handlers

Any and all of the above can be ignored by your handler, but accepting the server is often paramount to more powerful features such as delayed execution or logging.

Examples

# Add a handler
route <- route() |>
  route_add("get", "/:what", function(request, response, keys, ...) {
    message("Requesting", keys$what)
    TRUE
  })
route
#> A route with 1 handler
#> get:
#> • /:what

# Retrieve the handler
route |> route_get("get", "/:what")
#> A route with 1 handler
#> get:
#> • /:what

# Remove the handler
route |> route_remove("get", "/:what")
#> A route with 0 handlers