How to start your first Symfony base API with GraphQL under the hood

1. Symfony + GraphQL
Alex Demchenko
alex@lazy-ants.com

2. Alex Demchenko
Lazy Ants founder & CEO

3. GraphQL
query language and execution engine
https://graphql.org/

4. Created by Facebook at 2012

5. Become an open standard at 2015

6. Latest update at June 2018
http://facebook.github.io/graphql/June2018/

7. Improvements over REST

8. One endpoint
Query

9. Get User posts REST style
http://lznz.eu/api/user/444/posts

10. Get User posts REST style
http://lznz.eu/api/user/444/posts
- What information does that give us?

11. Get User posts REST style
http://lznz.eu/api/user/444/posts
- What information does that give us?
- What data will come from that request?

12. Get User posts REST style
You said Swager for API doc?

13. Get User posts REST style
fck tons of annotations
to explain each endpoints

14. Get User posts REST style
You are waste your time,
instead of bring
Business Value

15. Get User posts REST style
http://lznz.eu/api/user/444/posts
http://lznz.eu/api/post/4/comments?last=5
http://lznz.eu/api/post/5/comments?last=5

16. Ok Ok create a custom endpoint
http://lznz.eu/api/user/444/posts
?with=comments&lastComments=5

17. GraphQL style
query userPosts {
posts(userId: 45) {
id
title
text
createdAt
}
}

18. GraphQL style
query {
articles(first: 3, sortBy: “date”){
id
title
body
published
category{
id
name
}
}
}

19. Desktop or Mobile
query userPosts {
posts(userId: 45) {
id
title
text
createdAt
}
}
query userPosts {
posts(userId: 45) {
id
title
}
}

28. ERRORS?

29. Cursor Connections
#R2D2 ->"YXJyYXljb25uZWN0aW9uOjI="
query codeIDget3AfterCursor {
allPeople(
first: 3,
after: "YXJyYXljb25uZWN0aW9uOjI="
) {
edges {
node {
name
}
cursor
}
}
}
https://graphql.org/swapi-graphql/?query=query%20pumparam%20%7B%0A%09all

30. Cursor Connections
{
"data": {
"allPeople": {
"edges": [
...
{
"node": {
"name": "Owen Lars"
},
"cursor": "YXJyYXljb25uZWN0aW9uOjU="
}
]
}
}
}
https://graphql.org/swapi-graphql/?query=query%20pumparam%20%7B%0A%09all

31. GraphQL prevents HTTP overfetching

32. Mutations

33. Mutations
mutation {
createReview(input: {
episodeID: 4,
content: "hope is a good thing",
rating: 5
}) {
id
}
}

34. With GraphQL the server code
is clean and well-organized

35. Symfony implementation

36. https://github.com/
youshido-php/GraphQLBundle
275 Stars
https://github.com/youshido-php/GraphQL - 660 stars

37. https://github.com/
overblog/GraphQLBundle
338 Stars
https://github.com/webonyx/graphql-php - 2384 stars

38. Interface
# Resources/graphql/character.types.yml
Character:
type: interface
config:
fields:
id:
type: "String"
name:
type: "String"
friends:
type: "[Character]"
description: "The friends of the character."
appearsIn:
type: "[Film]"
description: "Which movies they appear in."

39. Object
# Resources/graphql/human.types.yml
Human:
type: object
config:
fields:
id:
type: "String"
name:
type: "String"
homeWorld:
type: World
interfaces: [Character]
isTypeOf: true

40. Entry point -> Query
# Resources/graphql/query.types.yml
Query:
type: object
config:
description: "All Star Wars queries"
fields:
allHumans:
type: "[Human]"
resolve: "@=resolver('allHumans', [args])" # Symfony Expression Language
human:
type: "Human"
resolve: "@=resolver('human', [args['id'])" # Symfony Expression Language
args:
id:
description: "Human's UUID"
type: "String!"

41. Mutation Entry Point
# Resources/graphql/Mutation.types.yml
Mutation:
type: object
config:
description: "All Star Wars mutations"
fields:
createReview:
args:
episode:
type: "String!"
content:
type: "String!"
rating:
type: "Int!"
type: Episode
resolve: "@=mutation('calculation_mutate_order', [args['calculationId'], ...])"

42. Resolver
# Resources/services.yml
services:
graphql.starwars.resolver.human:
class: Mefi/GraphQL/Starwars/Resolver/HumanResolver
arguments:
- "@repository.human"
tags:
- { name: overblog_graphql.resolver, alias: "allHumans", method: "resolveAllHumans" }
- { name: overblog_graphql.resolver, alias: "human", method: "resolveHuman" }

43. define Resolver class
# AppBundle/Resolver/HumanResolver.php
namespace AppBundleResolver;
use OverblogGraphQLBundleDefinitionArgument;
class HumanResolver
{
public function resolveAllHumans(Argument $args): array
{
// Do something with the $args
return $this->humanRepository->findAll();
}
public function resolveHuman(string $humanId): Human
{
try {
return $this->humanRepository->findById($humanId);
} catch (HumanNotFoundException $e) {
throw new UserError('This human was eliminated', 0, $e);
}
}
}

44. Versioning

45. /api/v1

46. /api/v1
/api/v2

47. /api/v1
/api/v2
/api/v3

48. No Way!

49. Just DEPRECATED

50. HUM?!?

51. A lot of argue, but that’s it!

52. Deprecated
# droid.types.yml
Droid:
type: object
config:
fields:
id:
type: "String"
name:
type: "String"
homeWorld:
type: World
interfaces: [Character]
isTypeOf: true

53. Deprecated
# droid.types.yml
Droid:
type: object
config:
fields:
id:
type: "String"
name:
type: "String"
deprecationReason: "Droids don't deserve names"
homeWorld:
type: World
interfaces: [Character]
isTypeOf: true

54. Heavy Queries?

55. Limiting Queries by Depth

56. Limiting Queries by Depth
/** @var GraphQLValidatorRulesQueryDepth $queryDepth */
$queryDepth = DocumentValidator::getRule('QueryDepth');
$queryDepth->setMaxQueryDepth($maxQueryDepth = 10);
GraphQL::execute(/*...*/);

57. Limiting Queries by Depth
or with OverBlogGraphQLBundle

58. Limiting Queries by Depth
or with OverBlogGraphQLBundle
# app/config/config.yml
overblog_graphql:
security:
query_max_depth: 10

59. Limiting Queries by Complexity

60. Limiting Queries by Complexity
/** @var GraphQLValidatorRulesQueryComplexity $queryComplexity */
$queryComplexity = DocumentValidator::getRule('QueryComplexity');
$queryComplexity->setMaxQueryComplexity($maxQueryComplexity = 110);
GraphQL::execute(/*...*/);

61. Limiting Queries by Complexity
or with OverBlogGraphQLBundle

62. Limiting Queries by Depth
or with OverBlogGraphQLBundle
# app/config/config.yml
overblog_graphql:
security:
query_max_complexity: 1000

63. Custom field Complexity
# Query.types.yml
Query:
type: object
config:
fields:
droid:
type: "Droid"
args:
id:
description: "id of the droid"
type: "String!"
resolve: "@=resolver('character_droid', [args])"

64. Custom field Complexity
# Query.types.yml
Query:
type: object
config:
fields:
droid:
type: "Droid"
complexity: '@=1000 + childrenComplexity'
args:
id:
description: "id of the droid"
type: "String!"
resolve: "@=resolver('character_droid', [args])"

65. Security

66. Field access control
# human.types.yml
Human:
type: object
config:
fields:
id:
type: "String"

67. Field access control
# human.types.yml
Human:
type: object
config:
fields:
id:
type: "String"
access: "@=isSuperAdmin()"

68. Field publicly Visible
# human.types.yml
Human:
type: object
config:
fields:
id:
type: "String"

69. Field publicly Visible
# human.types.yml
Human:
type: object
config:
fields:
id:
type: "String"
public: "@=service('security.authorization_checker').isGranted('ROLE_ADMIN')"

70. Links not just for me ;)
https://www.scalablepath.com/blog/how-to-build-graphql-app-php/ - best for
begginers
https://graphql.org/
http://facebook.github.io/graphql/June2018/#sec-Language
https://graphql.org/swapi-graphql/ - play with it!
https://github.com/chentsulin/awesome-graphql
https://www.apollographql.com/

71. Alex Deemann
alex@lazy-ants.com