Creates a Schema object from the defined GraphQL string and inserts the provided descriptions, resolve methods, resolve_type methods into the appropriate place.
Arguments
- schema
GraphQL schema string or Schema object
- ...
named lists of information to help produce the schema definition. See Details
Details
The ... should be named arguments whose values are lists of information. What information is needed for each type is described below.
ScalarTypeDefinition:
- resolve
function with two parameters:
x(the raw to be parsed, such as 5.0) andschema(the full Schema definition). Should return a parsed value- description
(optional) single character value that describes the Scalar definition
- parse_ast
(optional) function with two parameters:
obj(a GraphQL wrapped raw value, such as an object of class IntValue with value 5) andschema(the full Schema definition). If the function returnsNULLthen the AST could not be parsed.
EnumTypeDefinition:
- resolve
(optional) function with two parameters:
xandschema(the full Schema definition). Should return the valuexrepresents, such as the Star Wars Episode enum value "4" could represent Episode "NEWHOPE". By default, EnumTypeDefinitions will return the current value.- description
(optional) single character value that describes the Enum definition
- values
(optional) named list of enum value descriptions. Such as
values = list(ENUMA = "description for ENUMA", ENUMZ = "description for ENUMZ")
ObjectTypeDefinition:
- resolve
function with two parameters:
x(place holder value to be expanded into a named list) andschema(the full Schema definition). By using the resolve method, recursive relationships, such as friends, can easily be handled. The resolve function should return a fully named list of all the fields the definition defines. Missing fields are automatically interpreted asNULL.Values in the returned list may be a function of the form
function(obj, args, schema) {...}. This allows for fields to be determined dynamically and lazily. See howadd_humanmakes a field fortotalCredits, while theadd_droidpre computes the information.- description
(optional) single character value that describes the object
- fields
(optional) named list of field descriptions. Such as
fields = list(fieldA = "description for field A", fieldB = "description for field B")
InterfaceTypeDefinition and UnionTypeDefinition:
- resolve_type
function with two parameters:
x(a pre-resolved object value) andschema(the full Schema definition). This function is required to determine which object type is being used.resolve_typeis called before any ObjectTypeDefinitionresolvemethods are called.- description
(optional) single character value that describes the object
Examples
# \donttest{
library(magrittr)
## Set up data
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) %>% print()
#> $`1000`
#> $`1000`$id
#> [1] "1000"
#>
#> $`1000`$name
#> [1] "Luke Skywalker"
#>
#> $`1000`$appearsIn
#> [1] 4 5 6
#>
#> $`1000`$friends
#> [1] "1002" "1003" "2000" "2001"
#>
#> $`1000`$homePlanet
#> [1] "Tatooine"
#>
#> $`1000`$totalCredits
#> function(obj, args, schema) {
#> length(human$appearsIn)
#> }
#> <environment: 0x55c60ac9e638>
#>
#>
#> $`1002`
#> $`1002`$id
#> [1] "1002"
#>
#> $`1002`$name
#> [1] "Han Solo"
#>
#> $`1002`$appearsIn
#> [1] 4 5 6
#>
#> $`1002`$friends
#> [1] "1000" "1003" "2001"
#>
#> $`1002`$homePlanet
#> [1] "Corellia"
#>
#> $`1002`$totalCredits
#> function(obj, args, schema) {
#> length(human$appearsIn)
#> }
#> <environment: 0x55c60ac9f1d0>
#>
#>
#> $`1003`
#> $`1003`$id
#> [1] "1003"
#>
#> $`1003`$name
#> [1] "Leia Organa"
#>
#> $`1003`$appearsIn
#> [1] 4 5 6
#>
#> $`1003`$friends
#> [1] "1000" "1002" "2000" "2001"
#>
#> $`1003`$homePlanet
#> [1] "Alderaan"
#>
#> $`1003`$totalCredits
#> function(obj, args, schema) {
#> length(human$appearsIn)
#> }
#> <environment: 0x55c60ac9c050>
#>
#>
#> $`2000`
#> $`2000`$id
#> [1] "2000"
#>
#> $`2000`$name
#> [1] "C-3PO"
#>
#> $`2000`$appearsIn
#> [1] 4 5 6
#>
#> $`2000`$friends
#> [1] "1000" "1002" "1003" "2001"
#>
#> $`2000`$primaryFunction
#> [1] "Protocol"
#>
#> $`2000`$totalCredits
#> [1] 3
#>
#>
#> $`2001`
#> $`2001`$id
#> [1] "2001"
#>
#> $`2001`$name
#> [1] "R2-D2"
#>
#> $`2001`$appearsIn
#> [1] 4 5 6
#>
#> $`2001`$friends
#> [1] "1000" "1002" "1003"
#>
#> $`2001`$primaryFunction
#> [1] "Astromech"
#>
#> $`2001`$totalCredits
#> [1] 3
#>
#>
## End data set up
# Define the schema using GraphQL code
star_wars_schema <- Schema$new()
"
enum Episode { NEWHOPE, EMPIRE, JEDI }
" %>%
gqlr_schema(
Episode = list(
resolve = function(episode_id, schema) {
switch(as.character(episode_id),
"4" = "NEWHOPE",
"5" = "EMPIRE",
"6" = "JEDI",
"UNKNOWN_EPISODE"
)
}
)
) ->
episode_schema
# display the schema
episode_schema$get_schema()
#> <graphql definition>
#> | enum Episode {
#> | NEWHOPE
#> | EMPIRE
#> | JEDI
#> | }
# add the episode definitions to the Star Wars schema
star_wars_schema$add(episode_schema)
"
interface Character {
id: String!
name: String
friends: [Character]
appearsIn: [Episode]
}
" %>%
gqlr_schema(
Character = list(
resolve_type = function(id, schema) {
if (id %in% names(droid_data)) {
"Droid"
} else {
"Human"
}
}
)
) ->
character_schema
# print the Character schema with no extra formatting
character_schema$get_schema() %>% format() %>% cat("\n")
#> interface Character {
#> id: String!
#> name: String
#> friends: [Character]
#> appearsIn: [Episode]
#> }
star_wars_schema$add(character_schema)
"
type Droid implements Character {
id: String!
name: String
friends: [Character]
appearsIn: [Episode]
primaryFunction: String
}
type Human implements Character {
id: String!
name: String
friends: [Character]
appearsIn: [Episode]
homePlanet: String
}
" %>%
gqlr_schema(
Human = list(
# Add a resolve method for type Human that takes in an id and returns the human data
resolve = function(id, args, schema) {
human_data[[id]]
}
),
Droid = list(
# description for Droid
description = "A mechanical creature in the Star Wars universe.",
# Add a resolve method for type Droid that takes in an id and returns the droid data
resolve = function(id, schema) {
droid_data[[id]]
}
)
) ->
human_and_droid_schema
human_and_droid_schema$get_schema()
#> <graphql definition>
#> | 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
#> | }
star_wars_schema$add(human_and_droid_schema)
"
type Query {
hero(episode: Episode): Character
human(id: String!): Human
droid(id: String!): Droid
}
# the schema type must be provided if a query or mutation is to be executed
schema {
query: Query
}
" %>%
gqlr_schema(
Query = function(null, schema) {
list(
# return a function for key 'hero'
# the id will be resolved by the appropriate resolve() method of Droid or Human
hero = function(obj, args, schema) {
episode <- args$episode
if (identical(episode, 5) || identical(episode, "EMPIRE")) {
"1000" # Luke Skywalker
} 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
}
)
}
) ->
schema_def
# print Schema with no extra formatting
schema_def$get_schema() %>% format() %>% cat("\n")
#> type Query {
#> hero(episode: Episode): Character
#> human(id: String!): Human
#> droid(id: String!): Droid
#> }
#>
#> schema {
#> query: Query
#> }
star_wars_schema$add(schema_def)
# view the final schema definitiion
star_wars_schema$get_schema()
#> <graphql definition>
#> | 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
#> | }
# }