Server implementation of 'GraphQL' < http://graphql.github.io/graphql-spec/>, a query language originally created by Facebook for describing data requirements on complex application data models. Visit < http://graphql.org> to learn more about 'GraphQL'.
GraphQL is a data "query language created by Facebook in 2015 for describing the capabilities and requirements of data models for client‐server applications". The GraphQL specification can be read on their hosted github. A cliff notes version is described on Facebook's github. To learn more about the GraphQL language, I highly recommend Facebook's public GraphQL website.
This package pulls inspiration from Facebook's graphql-js and Mathew Mueller's graph.ql. I wanted the full functionality of GraphQL, but I didn't want to force users to write full object definitions when can already be defined with GraphQL syntax.
gqlr
merges R's rapid development speed with the consistent query language of GraphQL.
# The development version from GitHub:# install.packages("devtools")devtools::install_github("schloerke/gqlr")
If you encounter a clear bug, please file a minimal reproducible example on github.
library(magrittr)library(gqlr) schema <- " type Hello { world: String } schema { query: Hello }" %>% gqlr_schema() execute_request("{world}", schema, initial_value = list(world = "Hi!"))# {# "data": {# "world": "Hi!"# }# }
add_human <- function(human_data, id, name, appear, home, friend) { human <- list(id = id, name = name, appearsIn = appear, friends = friend, homePlanet = home) # set up a function to be calculated if the field totalCredits is required human$totalCredits <- function(obj, args, schema) { length(human$appearsIn) } human_data[[id]] <- human human_data}add_droid <- function(droid_data, id, name, appear, pf, friend) { droid <- list(id = id, name = name, appearsIn = appear, friends = friend, primaryFunction = pf) # set extra fields manually droid$totalCredits <- length(droid$appearsIn) droid_data[[id]] <- droid droid_data} human_data <- list() %>% add_human("1000", "Luke Skywalker", c(4, 5, 6), "Tatooine", c("1002", "1003", "2000", "2001")) %>% add_human("1002", "Han Solo", c(4, 5, 6), "Corellia", c("1000", "1003", "2001")) %>% add_human("1003", "Leia Organa", c(4, 5, 6), "Alderaan", c("1000", "1002", "2000", "2001")) droid_data <- list() %>% add_droid("2000", "C-3PO", c(4, 5, 6), "Protocol", c("1000", "1002", "1003", "2001")) %>% add_droid("2001", "R2-D2", c(4, 5, 6), "Astromech", c("1000", "1002", "1003")) all_characters <- list() %>% append(human_data) %>% append(droid_data)all_characters[[1]]# $id# [1] "1000"## $name# [1] "Luke Skywalker"## $appearsIn# [1] 4 5 6## $friends# [1] "Tatooine"## $homePlanet# [1] "1002" "1003" "2000" "2001"## $totalCredits# function (obj, args, schema)# {# length(human$appearsIn)# }# <environment: 0x7fadd8ca2038>
"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 executedschema { 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"# }# ]# }# }# }
# Rserver(star_wars_schema, log = TRUE)
Explore with curl
# 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 # }
WOMBAT2016 in Melbourne, Australia; Feb 2016.