Async client for different request types

Description

Async client for different request types

Arguments

Details

Methods

request()

Execute asynchronous requests - returns: nothing, responses stored inside object, though will print messages if you choose verbose output

requests()

list requests - returns: a list of HttpRequest objects, empty list before requests made

responses()

list responses - returns: a list of HttpResponse objects, empty list before requests made

parse(encoding = "UTF-8")

parse content - returns: character vector, empty character vector before requests made

status_code()

(integer) HTTP status codes - returns: numeric vector, empty numeric vector before requests made

status()

(list) HTTP status objects - returns: a list of http_code objects, empty list before requests made

content()

raw content - returns: raw list, empty list before requests made

times()

curl request times - returns: list of named numeric vectors, empty list before requests made

Value

An object of class AsyncVaried with variables and methods. Responses are returned in the order they are passed in. We print the first 10.

Failure behavior

HTTP requests mostly fail in ways that you are probably familiar with, including when there's a 400 response (the URL not found), and when the server made a mistake (a 500 series HTTP status code).

But requests can fail sometimes where there is no HTTP status code, and no agreed upon way to handle it other than to just fail immediately.

When a request fails when using synchronous requests (see [HttpClient]) you get an error message that stops your code progression immediately saying for example:

- "Could not resolve host: https://foo.com" - "Failed to connect to foo.com" - "Resolving timed out after 10 milliseconds"

However, for async requests we don't want to fail immediately because that would stop the subsequent requests from occurring. Thus, when we find that a request fails for one of the reasons above we give back a [HttpResponse] object just like any other response, and:

- capture the error message and put it in the 'content' slot of the response object (thus calls to 'content' and 'parse()' work correctly) - give back a '0' HTTP status code. we handle this specially when testing whether the request was successful or not with e.g., the 'success()' method

See Also

Other async: Async

Examples

## Not run: 
# pass in requests via ...
req1 <- HttpRequest$new(
  url = "https://httpbin.org/get",
  opts = list(verbose = TRUE),
  headers = list(foo = "bar")
)$get()
req2 <- HttpRequest$new(url = "https://httpbin.org/post")$post()

# Create an AsyncVaried object
out <- AsyncVaried$new(req1, req2)

# before you make requests, the methods return empty objects
out$status()
out$status_code()
out$content()
out$times()
out$parse()
out$responses()

# make requests
out$request()

# access various parts
## http status objects
out$status()
## status codes
out$status_code()
## content (raw data)
out$content()
## times
out$times()
## parsed content
out$parse()
## response objects
out$responses()

# pass in requests in a list via .list param
reqlist <- list(
  HttpRequest$new(url = "https://httpbin.org/get")$get(),
  HttpRequest$new(url = "https://httpbin.org/post")$post(),
  HttpRequest$new(url = "https://httpbin.org/put")$put(),
  HttpRequest$new(url = "https://httpbin.org/delete")$delete(),
  HttpRequest$new(url = "https://httpbin.org/get?g=5")$get(),
  HttpRequest$new(
    url = "https://httpbin.org/post")$post(body = list(y = 9)),
  HttpRequest$new(
    url = "https://httpbin.org/get")$get(query = list(hello = "world"))
)

out <- AsyncVaried$new(.list = reqlist)
out$request()
out$status()
out$status_code()
out$content()
out$times()
out$parse()

# using auth with async
url <- "https://httpbin.org/basic-auth/user/passwd"
auth <- auth(user = "user", pwd = "passwd")
reqlist <- list(
  HttpRequest$new(url = url, auth = auth)$get(),
  HttpRequest$new(url = url, auth = auth)$get(query = list(a=5)),
  HttpRequest$new(url = url, auth = auth)$get(query = list(b=3))
)
out <- AsyncVaried$new(.list = reqlist)
out$request()
out$status()
out$parse()

# failure behavior
## e.g. when a URL doesn't exist, a timeout, etc.
reqlist <- list(
  HttpRequest$new(url = "http://stuffthings.gvb")$get(),
  HttpRequest$new(url = "https://httpbin.org")$head(),
  HttpRequest$new(url = "https://httpbin.org", 
   opts = list(timeout_ms = 10))$head()
)
(tmp <- AsyncVaried$new(.list = reqlist))
tmp$request()
tmp$responses()
tmp$parse("UTF-8")

## End(Not run)