Welcome back to my series how to develop GraphQL API for rails applications from scratch.
Authentication - signIn method
To authenticate our users, we need to add jwt gem to our Gemfile
bundle add jwt
and create app/models/auth_token.rb
class AuthToken
def self.key
Rails.application.credentials.jwt_secret
end
def self.token(user)
payload = {user_id: user.id}
JWT.encode(payload, key)
end
def self.verify(token)
result = JWT.decode(token, key)[0]
User.find_by(id: result["user_id"])
rescue JWT::VerificationError, JWT::DecodeError
nil
end
end
How does it work. We use jwt_secret which is stored in rails credentials to create a token which stores user_id and to find User record by token.
Let’s create our jwt_secret for development and test environments
rails credentials:edit --environment=development
rails credentials:edit --environment=test
and add the following line
jwt_secret: "secret"
Btw, don’t forget to generate secure keys using
rails secret
Let’s test it out.
AuthToken.key # "secret"
user = User.create(email: FFaker::Internet.email, password: SecureRandom.hex, first_name: FFaker::Name.first_name, last_name: FFaker::Name.last_name )
AuthToken.token(user) # "token-secret-value"
AuthToken.verify("token-secret-value") # returns User instance
Next, let’s implement current_user method. We need to update app/controllers/graphql_controller.rb
class GraphQLController < ApplicationController
protect_from_forgery with: :null_session # <-- uncomment this line
def execute
variables = prepare_variables(params[:variables])
query = params[:query]
operation_name = params[:operationName]
context = {
current_user: current_user # <-- add this line
}
result = GraphqlFromScratchSchema.execute(query, variables: variables, context: context, operation_name: operation_name)
render json: result
rescue => e
raise e unless Rails.env.development?
handle_error_in_development(e)
end
############### Add this method
def current_user
return nil if request.headers["Authorization"].blank?
token = request.headers["Authorization"].split(" ").last
return nil if token.blank?
AuthToken.verify(token)
end
###############
end
We need to create our mutation in app/graphql/mutations/users/sign_in.rb
module Mutations::Users
class SignIn < Mutations::BaseMutation
graphql_name "signIn"
argument :email, String, required: true
argument :password, String, required: true
field :user, Types::UserType, null: true
field :token, String, null: true
def resolve(email:, password:)
user = User.find_by(email:)
errors = {}
if user&.authenticate(password)
context[:current_user] = user
token = AuthToken.token(user)
{token: AuthToken.token(user), user:, success: true}
else
user = nil
context[:current_user] = nil
raise GraphQL::ExecutionError, "Incorrect Email/Password"
end
end
end
end
and add it to app/graphql/types/mutation_type.rb
module Types
class MutationType < Types::BaseObject
field :sign_up, mutation: Mutations::Users::SignUp
field :sign_in, mutation: Mutations::Users::SignIn # <-- add this line
end
end
Let’s try it in our GraphQL console
mutation {
signIn(input: { email: "test@example.com", password: "1234567890" }) {
user {
id
email
name
}
success
token
}
}
And you’ll see a result
{
"data": {
"signIn": {
"user": {
"id": "9a7fb463-2493-48f6-8641-509f58c9b47f",
"email": "test@example.com",
"name": "Alexey Poimtsev"
},
"success": true,
"token": "correct-token"
}
}
}
In case of wrong email/password
mutation {
signIn(input: { email: "test@example.com", password: "111" }) {
user {
id
email
name
}
success
token
}
}
You’ll see an error message
{
"data": {
"signIn": null
},
"errors": [
{
"message": "Incorrect Email/Password",
"locations": [
{
"line": 2,
"column": 3
}
],
"path": ["signIn"]
}
]
}
Don’t forget to write specs spec/graphql/mutations/users/sign_in_spec.rb
require "rails_helper"
RSpec.describe "#signIn mutation" do
before do
@password = SecureRandom.hex
@user = FactoryBot.create(:user, email: "user@example.com", password: @password)
end
let(:mutation) do
<<~GQL
mutation signIn($email: String!, $password: String!) {
signIn(input: {
email: $email
password: $password
}) {
user {
id
email
name
}
token
}
}
GQL
end
it "is successful with correct email and password" do
result = GraphqlFromScratchSchema.execute(mutation, variables: {
email: "user@example.com",
password: @password
})
expect(result.dig("data", "signIn", "errors")).to be_nil
expect(result.dig("data", "signIn", "user", "email")).to eq("user@example.com")
expect(result.dig("data", "signIn", "user", "id")).to be_present
expect(result.dig("data", "signIn", "token")).to be_present
end
it "fails with wrong password" do
result = GraphqlFromScratchSchema.execute(mutation, variables: {
email: "user@example.com",
password: "wrong-password"
})
expect(result.dig("data", "signIn", "user", "id")).to be_nil
expect(result.dig("data", "signIn", "token")).to be_nil
expect(result.dig("errors", 0, "message")).to eq("Incorrect Email/Password")
end
end
Let’s break for a while to improve our code a bit.
Improvements - whoAmI method, inflections and GraphQL schema dump
Let’s add a helper method to easily test our authentication. Add following lines to app/graphql/types/query_type.rb (you can replace test_field method)
field :who_am_i, String, null: false,
description: "Who am I"
def who_am_i
"You've authenticated as #{context[:current_user].presence || "guest"}."
end
If you’re not authenticated
{
whoAmI
}
you’ll see
{
"data": {
"whoAmI": "You've authenticated as guest."
}
}
But if you use correct token
{
"Authorization": "correct-token"
}
You’ll see
{
"data": {
"whoAmI": "You've authenticated as Alexey Poimtsev."
}
}
Let’s play with inflections. Open file config/initializers/inflections.rb and make in looks like
ActiveSupport::Inflector.inflections(:en) do |inflect|
inflect.acronym "RESTful"
inflect.acronym "GraphQL" # <-- add this line
end
Now, we can rename in app/controllers/graphql_controller.rb class name GraphqlController to GraphQLController. Looks better, isn’t it? But don’t forget to rename every Graphql string in class names to GraphQL.
Let’s add rake task for schema dump. I’ve created lib/tasks/graphql.rake with following code
namespace :graphql do
desc "Dump GraphQL schema"
task dump_schema: :environment do
# Get a string containing the definition in GraphQL IDL:
schema_defn = GraphQLFromScratchSchema.to_definition
# Choose a place to write the schema dump:
schema_path = "app/graphql/schema.graphql"
# Write the schema dump to that file:
File.write(Rails.root.join(schema_path), schema_defn)
puts "Updated #{schema_path}"
end
end
and added spec in spec/graphql/schema_spec.rb
require "rails_helper"
RSpec.describe "GraphQL schema" do
it "must be reflected in the .graphql file" do
current_defn = GraphQLFromScratchSchema.to_definition
printout_defn = File.read(Rails.root.join("app/graphql/schema.graphql"))
assert_equal(current_defn, printout_defn, "Update the printed schema with `bundle exec rake dump_schema`")
end
end
Now, with
rake graphql:dump_schema
I’ll have updated schema in app/graphql/schema.graphql and specs will remind me to update it.