Querying GraphQL with R using httr

graphql-example.R

# Assuming the following GraphQL: https://github.com/calebmer/postgraphql/tree/master/examples/forum
# Deploy to AWS via https://github.com/rentrop/serverless-postgraphql

require(httr)
require(jsonlite)

# Define helper function --------------------------------------------------

url <- "https://your-endpoint/graphql"
GQL <- function(query, 
                ..., 
                .token = NULL,
                .variables = NULL, 
                .operationName = NULL, 
                .url = url){
  pbody <- list(query = query, variables = .variables, operationName = .operationName)
  if(is.null(.token)){
    res <- POST(.url, body = pbody, encode="json", ...)
  } else {
    auth_header <- paste("bearer", .token)
    res <- POST(.url, body = pbody, encode="json", add_headers(Authorization=auth_header), ...)
  }
  res <- content(res, as = "parsed", encoding = "UTF-8")
  if(!is.null(res$errors)){
    warning(toJSON(res$errors))
  }
  res$data
}


# Define queries ----------------------------------------------------------

auth_query <- 'mutation {
  authenticate(input: {email: "[email protected]", password: "iFbWWlc"}) {
    jwtToken
  }
}'

current_person_query <- '{
  currentPerson {
    fullName,
    latestPost{
      headline
    }
  }
}'


# Run queries -------------------------------------------------------------
token <- GQL(auth_query)$authenticate$jwtToken

GQL(current_person_query, .token = token)

# $currentPerson
# $currentPerson$fullName
# [1] "Sara Powell"
# 
# $currentPerson$latestPost
# $currentPerson$latestPost$headline
# [1] "Ameliorated optimal emulation"


# (optional) Simplify result ----------------------------------------------

require(purrr)
flatten(GQL(current_person_query, .token = token))
# $fullName
# [1] "Sara Powell"
# 
# $latestPost
# $latestPost$headline
# [1] "Ameliorated optimal emulation"


# A more complex example --------------------------------------------------

all_people_query <- '{
  allPeople(first: 3) {
    edges {
      node {
        id
        fullName
        latestPost {
          id
          headline
        }
      }
    }
  }
}'


GQL(all_people_query, .token = token)$allPeople$edges %>% 
  map_df(~transpose(.) %>% simplify_all)
# # A tibble: 3 × 3
#        id      fullName latestPost
#     <int>         <chr>     <list>
#   1     1   Sara Powell <list [2]>
#   2     2    Andrea Fox <list [2]>
#   3     3 Stephen Banks <list [2]>