Using cookiemonster

Reading and storing cookies

Welcome to the cookiemonster package, a one-stop solution to help you navigate the delicious world of browser cookies! In this vignette, we will explain what browser cookies are, how to read and store them using the cookiemonster package, and interact with them using the modern httr2 package, the legacy httr package, and the powerful curl package.

What are Browser Cookies?

This package helps you manage browser cookies in R, making it easy to work with cookies when sending HTTP requests. Before we dive into the functions and features of the package, let’s briefly discuss what browser cookies are. Browser cookies are small pieces of data that websites send to your browser to store and later retrieve. They help websites remember your preferences, login information, or even the items in your shopping cart. Cookies play a crucial role in making your browsing experience smooth and personalized. In R browser cookies come in handy when working with tasks that involve web interactions, like web scraping, browsing automation, website testing, or API calls that require authentication. They allow your scripts to efficiently mimic browser behaviour and maintain sessions as well as user-specific data.

Reading and Storing Cookies

Using the cookiemonster package, we can easily read and store cookies for further use. First, let’s load the package:

library(cookiemonster)

To use cookies with the cookiemonster, you will need to export the necessary cookies from your browser after visiting or logging into a website. To do this, you can use browser extensions like “Get cookies.txt” for Chromium-based browsers or “cookies.txt” for Firefox.

Let’s import an example cookie file provided by the cookiemonster package:

file.copy(
  from = system.file("extdata", "cookies.txt", package = "cookiemonster"),
  to = "."
)

Now, let’s add the cookies from the file to our cookie jar:

add_cookies(cookiefile = "cookies.txt")

Using cookiemonster with other packages

Using Stored Cookies with httr2

Now let’s see how to use stored cookies with the httr2 package:

library(httr2)
resp <- request("https://hb.cran.dev/cookies/set") |> # start a request
  req_options(cookie = get_cookies("hb.cran.dev", as = "string")) |> # add cookies to be sent with it
  req_perform() # perform the request

resp |> 
  resp_body_json()
#> $cookies
#> $cookies$cookies
#> [1] "allow"
#> 
#> $cookies$easy
#> [1] "true"
#> 
#> $cookies$test
#> [1] "true"

As you can see, the individual cookie values we see above are returned correctly. This is because the server at https://hb.cran.dev is configured to echo requests send to it. It shows us that the correct cookies were send (hooray!).

Using Stored Cookies with httr

To use stored cookies with the legacy httr package:

library(httr)
GET("https://hb.cran.dev/cookies/set", set_cookies(get_cookies("hb.cran.dev", as = "vector")))
#> Response [https://hb.cran.dev/cookies]
#>   Date: 2023-11-30 14:48
#>   Status: 200
#>   Content-Type: application/json
#>   Size: 88 B
#> {
#>   "cookies": {
#>     "cookies": "allow", 
#>     "easy": "true", 
#>     "test": "true"
#>   }
#> }

This code uses the ‘httr’ library to set cookies from the ‘https://hb.cran.dev’ website (a test website for development). The GET function is used to set the cookies, and the set_cookies function add cookies to the request.

Using Stored Cookies with curl

curl is the backbone of both httr and httr2, which provide a more straightforward interface for it. You can also use curl directly though (which is only recommended for advanced users though). To make the same request as above, we can use this code:

library(curl)
h <- new_handle()
handle_setopt(h, cookie = get_cookies("hb.cran.dev", as = "string"))
resp <- curl_fetch_memory("https://hb.cran.dev/cookies/set", handle = h)
jsonlite::fromJSON(rawToChar(resp$content))
#> $cookies
#> $cookies$cookies
#> [1] "allow"
#> 
#> $cookies$easy
#> [1] "true"
#> 
#> $cookies$test
#> [1] "true"

If the curl response contains new cookies:

h2 <- new_handle()
resp <- curl_fetch_memory("https://hb.cran.dev/cookies/set?new_cookies=moo", handle = h2)
handle_cookies(h2)
#>        domain  flag path secure expiration        name value
#> 1 hb.cran.dev FALSE    /  FALSE        Inf new_cookies   moo

Use store_cookies to store them in your jar:

new_cookies <- handle_cookies(h2)
store_cookies(new_cookies)
get_cookies("hb.cran.dev")
#> # A tibble: 1 × 7
#>   domain      flag  path  secure expiration name        value
#>   <chr>       <lgl> <chr> <lgl>  <dttm>     <chr>       <chr>
#> 1 hb.cran.dev FALSE /     FALSE  Inf Inf    new_cookies moo

Keep in mind that adding cookies for a domain will replace all previously stored cookies for that domain by default.

Now that you have an understanding of how the cookiemonster package can be used with httr2, httr, and curl, you’re ready to take control of browser cookies in your R projects! Happy coding and stay sharp, cookie monsters!