ruby-graphql-server/app.rb at main · smart-developer1791/ruby-graphql-server · GitHub

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require "bundler/setup"

# Load the appropriate gem groups depending on environment.
# - In production (or on Render), we load only :default and :production gems.
# - In development, we load :default and :development gems.
if ENV['RACK_ENV'] == 'production' || ENV['RENDER']
  Bundler.require(:default, :production)
else
  Bundler.require(:default, :development)
end

require "sinatra"
require "graphql"
require "json"

# Enable Sinatra auto-reloading only in development.
# This lets the server restart automatically when files change.
configure :development do
  require "sinatra/reloader"
end

# In-memory sample user data.
# This acts as a small mock database for demo purposes.
USERS = [
  { id: 1, name: "Alice", email: "alice@example.com" },
  { id: 2, name: "Bob", email: "bob@example.com" },
  { id: 3, name: "Carol", email: "carol@example.com" }
]

# -------------------------------
# GraphQL Type Definitions
# These types define the structure of returned data.
# -------------------------------

class UserType < GraphQL::Schema::Object
  # A user has 3 fields: id, name, email.
  field :id, ID, null: false
  field :name, String, null: false
  field :email, String, null: false
end

class MessageType < GraphQL::Schema::Object
  # Returned by the sendMessage mutation.
  field :message, String, null: false
  field :timestamp, String, null: false
end

# -------------------------------
# GraphQL Query Root
# This defines all available read-only operations.
# -------------------------------

class QueryType < GraphQL::Schema::Object
  # A simple "hello" field for testing.
  field :hello, String, null: false

  # Returns an array of all users.
  field :users, [UserType], null: false

  # Returns a single user by ID.
  field :user, UserType, null: true do
    argument :id, ID, required: true
  end

  # Resolver for hello
  def hello
    "Hello from GraphQL!"
  end

  # Resolver for users list
  def users
    USERS
  end

  # Resolver for a single user by ID
  def user(id:)
    USERS.find { |u| u[:id].to_s == id.to_s }
  end
end

# -------------------------------
# GraphQL Mutation Root
# This defines write/update operations.
# -------------------------------

class MutationType < GraphQL::Schema::Object
  # A mutation that accepts a message and returns it with a timestamp.
  field :send_message, MessageType, null: false do
    argument :message, String, required: true
  end

  # Mutation resolver
  def send_message(message:)
    { message: message, timestamp: Time.now.to_s }
  end
end

# -------------------------------
# GraphQL Schema Configuration
# Connects Query and Mutation to the schema object.
# -------------------------------

class MySchema < GraphQL::Schema
  query(QueryType)
  mutation(MutationType)
end

# -------------------------------
# GraphQL HTTP Endpoint (POST)
# All GraphQL requests are sent to /graphql.
# -------------------------------

post "/graphql" do
  # Parse JSON request body.
  payload = JSON.parse(request.body.read)

  # Execute the GraphQL query with optional variables.
  result = MySchema.execute(payload["query"], variables: payload["variables"])

  # Return JSON response.
  content_type :json
  result.to_json
end

# -------------------------------
# GraphiQL Web UI
# Available at the root path `/`.
# This is an in-browser IDE for GraphQL queries and mutations.
# -------------------------------

get "/" do
  content_type :html
  <<-HTML
  <!DOCTYPE html>
  <html>
    <head>
      <title>Ruby GraphQL Server</title>
      <!-- Load GraphiQL CSS -->
      <link href="https://unpkg.com/graphiql@2.2.0/graphiql.min.css" rel="stylesheet" />
    </head>
    <body style="margin:0; height:100vh;">
      <!-- GraphiQL UI container -->
      <div id="graphiql" style="height:100vh;"></div>

      <!-- Load React (required by GraphiQL) -->
      <script src="https://unpkg.com/react@18.2.0/umd/react.production.min.js"></script>

      <!-- Load ReactDOM (required by GraphiQL) -->
      <script src="https://unpkg.com/react-dom@18.2.0/umd/react-dom.production.min.js"></script>

      <!-- Load GraphiQL library -->
      <script src="https://unpkg.com/graphiql@2.2.0/graphiql.min.js"></script>

      <script>
        // GraphQL fetcher function used by the GraphiQL UI.
        const graphQLFetcher = graphQLParams =>
          fetch('/graphql', {
            method: 'post',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(graphQLParams),
          }).then(response => response.json());

        // Render GraphiQL into the page.
        ReactDOM.render(
          React.createElement(GraphiQL, { fetcher: graphQLFetcher }),
          document.getElementById('graphiql')
        );
      </script>
    </body>
  </html>
  HTML
end