gqlr: A GraphQL Implementation in R

# The development version from GitHub:
# install.packages("devtools")
devtools::install_github("schloerke/gqlr")

"
enum Episode { NEWHOPE, EMPIRE, JEDI }

interface Character {
  id: String!
  name: String
  friends: [Character]
  appearsIn: [Episode]
}

type Droid implements Character {
  id: String!
  name: String
  friends: [Character]
  appearsIn: [Episode]
  primaryFunction: String
}
type Human implements Character {
  id: String!
  name: String
  friends: [Character]
  appearsIn: [Episode]
  homePlanet: String
}

type Query {
  hero(episode: Episode): Character
  human(id: String!): Human
  droid(id: String!): Droid
}
# the schema type must be provided if a query or mutation is to be executed
schema {
  query: Query
}
" %>%
  gqlr_schema(
    Episode = list(
      resolve = function(episode_id, schema) {
        switch(as.character(episode_id),
          "4" = "NEWHOPE",
          "5" = "EMPIRE",
          "6" = "JEDI",
          "UNKNOWN_EPISODE"
        )
      }
    ),
    Character = list(
      resolve_type = function(id, schema) {
        ifelse(id %in% names(droid_data), "Droid", "Human")
      }
    ),
    Human = list(
      # Add a resolve method for type Human that takes in an id and returns the human data
      resolve = function(id, args, schema) {
        human_data[[id]]
      }
    ),
    Droid = list(
      # description for Droid
      description = "A mechanical creature in the Star Wars universe.",
      # Add a resolve method for type Droid that takes in an id and returns the droid data
      resolve = function(id, schema) {
        droid_data[[id]]
      }
    ),
    Query = function(null, schema) {
      list(
        # return a function for key 'hero'
        # the id will be resolved by the appropriate resolve() method of Droid or Human
        hero = function(obj, args, schema) {
          episode <- args$episode
          if (identical(episode, 5) || identical(episode, "EMPIRE")) {
            "1000" # Luke
          } else {
            "2001" # R2-D2
          }
        },
        # the id will be resolved by the Human resolve() method
        human = function(obj, args, schema) {
          args$id
        },
        # the id will be resolved by the Droid resolve() method
        droid = function(obj, args, schema) {
          args$id
        }
      )
    }
  ) ->
star_wars_schema

# Use the resolve method to initialize the data
"
{
  hero {
    id
    name
    friends {
      id
      name
    }
  }
}
" %>%
  execute_request(star_wars_schema)
# {
#   "data": {
#     "hero": {
#       "id": "2001",
#       "name": "R2-D2",
#       "friends": [
#         {
#           "id": "1000",
#           "name": "Luke Skywalker"
#         },
#         {
#           "id": "1002",
#           "name": "Han Solo"
#         },
#         {
#           "id": "1003",
#           "name": "Leia Organa"
#         }
#       ]
#     }
#   }
# }


# Use variables...
"
query FetchSomeIDQuery($someId: String!) {
  human(id: $someId) {
    name
  }
}
" %>%
  execute_request(star_wars_schema, variables = list(someId = "1000"))
# {
#   "data": {
#     "human": {
#       "name": "Luke Skywalker"
#     }
#   }
# }


# Introspection
"
query IntrospectionTypeQuery {
  __type(name: \"Droid\") {
    kind
    name
    fields {
      name
    }
  }
}
" %>%
  execute_request(star_wars_schema)
# {
#   "data": {
#     "__type": {
#       "kind": "OBJECT",
#       "name": "Droid",
#       "fields": [
#         {
#           "name": "id"
#         },
#         {
#           "name": "name"
#         },
#         {
#           "name": "friends"
#         },
#         {
#           "name": "appearsIn"
#         },
#         {
#           "name": "primaryFunction"
#         },
#         {
#           "name": "__typename"
#         }
#       ]
#     }
#   }
# }

# R
gqlr:::server(star_wars_schema, log = TRUE) # forgot to export

# GET R2-D2 and his friends' names
curl '127.0.0.1:8000/graphql?query=%7Bhero%7Bname%7D%7D&pretty=TRUE'
# {
#   "data": {
#     "hero": {
#       "name": "R2-D2"
#     }
#   }
# }

# POST for R2-D2 and his friends' names (no need to url escape the query)
curl --data '{"query":"{hero{name}}"}' '127.0.0.1:8000/graphql' # defaults to parse as JSON
# {"data":{"hero":{"name":"R2-D2"}}}

curl --data '{"query":"{hero{name}}"}' '127.0.0.1:8000/graphql' --header "Content-Type:application/json"
# {"data":{"hero":{"name":"R2-D2"}}}

curl --data '{hero{name}}' '127.0.0.1:8000/graphql' --header "Content-Type:application/graphql"
# {"data":{"hero":{"name":"R2-D2"}}}


# GET Schema definition
curl '127.0.0.1:8000/'
# enum Episode {
#   NEWHOPE
#   EMPIRE
#   JEDI
# }
#
# type Droid implements Character {
#   id: String!
#   name: String
#   friends: [Character]
#   appearsIn: [Episode]
#   primaryFunction: String
# }
#
# type Human implements Character {
#   id: String!
#   name: String
#   friends: [Character]
#   appearsIn: [Episode]
#   homePlanet: String
# }
#
# type Query {
#   hero(episode: Episode): Character
#   human(id: String!): Human
#   droid(id: String!): Droid
# }
#
# interface Character {
#   id: String!
#   name: String
#   friends: [Character]
#   appearsIn: [Episode]
# }
#
# schema {
#   query: Query
# }