Class: GraphqlServer

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql_server.rb

Defined Under Namespace

Classes: InvalidRequestTypeError, PostBodyMissing

Instance Method Summary collapse

Constructor Details

#initialize(*args, path: nil, type_def: nil, resolver: nil, schema: nil, context: nil) ⇒ GraphqlServer

Initilizes GraphqlServer as a Rack app or middleware

This Rack middleware (or app) implements a spec-compliant GraphQL server which can be queried from any GraphQL client. It can be used with a provided GraphQL schema or can build one from a type definition and a resolver hash.

Parameters:

  • *args (Array<Object>) —

    The first argument should be ‘app` when used as a middleware

  • String —

    path Also for middleware, we will use path to determine when to process GraphQL, defaults to ‘/’

  • String —

    type_def A schema definition string, or a path to a file containing the definition

  • Hash —

    resolver A hash with callables for handling field resolution

  • GraphQL::Schema —

    schema Use this schema if ‘type_def` and `resolver` is nil

  • Hash —

    context



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# File 'lib/graphql_server.rb', line 20

def initialize(*args , path: nil, type_def: nil, resolver: nil, schema: nil, context: nil)
  @app = args && args[0]
  @context = context
  @path = (@app && !path) ? '/' : path
  @schema = type_def && resolver ? GraphQL::Schema.from_definition(type_def, default_resolve: resolver) : schema
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/graphql_server.rb', line 31

def call(env)
  request = Rack::Request.new(env)

  # only resolve when url matches `path` if we're in a middleware
  return @app.call(env) if middleware? && @path != request.path_info
  
  # graphql accepts GET and POST requests
  raise InvalidRequestTypeError unless request.get? || request.post?

  payload = if request.get?
    request.params
  elsif request.post?
    body = request.body.read
    raise PostBodyMissing if body.empty?
    payload = JSON.parse(body)
  end

  response = @schema.execute(
    payload['query'], 
    variables: payload['variables'],
    operation_name: payload['operationName'],
    context: @context, 
  ).to_json
  
  [200, {'Content-Type' => 'application/json', 'Content-Length' => response.bytesize.to_s}, [response]]
rescue InvalidRequestTypeError
  # Method Not Allowed
  [405, {"Content-Type" => "text/html"}, ["GraphQL Server supports only GET/POST requests"]]
rescue PostBodyMissing
  # Bad Request
  [400, {"Content-Type" => "text/html"}, ["POST body missing"]]
end

#middleware? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/graphql_server.rb', line 27

def middleware?
  !@app.nil?
end