Accessing the RateBeer API with R Using httr

Hello, httr

httr is a package developed by Hadley Wickham of RStudio to make it easy to make HTTP requests. the package and the nuances of HTTP wont be gone into here, but some good resources for httr include the quickstart vignette, and Bradley Boehmke’s post on using httr. The httr syntax is quite simple. The main functions are curl verbs (httr is a wrapper for curl functions), and the function arguments all start with the URL and are then followed by things to modify the URL and to send with the URL.

RateBeer’s API is at https://api.ratebeer.com/v1/api/graphql. In the header of the request, content type and response type are required along with an API key. The query itself modifies the URL to call. So, my call to the RateBeer API to get the beers made by yards looks like this:

library(httr)

API_key <- Sys.getenv("rateBeer_API_key") 

URL <- "https://api.ratebeer.com/v1/api/graphql"

beers_by_yards <- POST(URL,
         body = list(
           query = 
"query{
  beersByBrewer(brewerId: 166) {
    totalCount
    items{
      name
      abv
      averageRating
      ratingCount
      isRetired
      style{
        name
      }
    }
  }
}",
           variables = "{}", 
           operationName = NULL),
         encode = "json", # tells httr to encode the body of the request as json
         add_headers("content-type" = "application/json", 
                     "Accept" = "application/json", 
                     "x-api-key" = API_key))

Parsing the Response

content() is httr’s function for extracting content from a request. Using the type = argument, we can have the function give us the data from the request as valid JSON. then we can use the jsonlite package to make the data easier to work with.

library(jsonlite)

json <- content(beers_by_yards, type = "text")

parsed_json <- fromJSON(json, flatten = TRUE)

Recall that the response to the request was supposed to be JSON? This means that all of our items are nested in the same way as we requested them. So, to get the number of beers that Yards makes, as well as a data frame with those beers, we work through those levels.

beer_count <- parsed_json$data$beersByBrewer$totalCount

beer_df <- parsed_json$data$beersByBrewer$items

beer_count

## [1] 126

kable(beer_df, "html") %>%
  kable_styling(bootstrap_options = c("striped", "hover"))

So, where’s all 111 beers? The API gives us 10 beers at a time. When We make the request to the API, we can tell it where to start that list of 10 beers, alongside our request to look at beers from a certain brewery.

In my next post, I’ll show how we can get all 111 of those beers and beers from other breweries, programmatically.