GraphQL
GraphQL was developed to cope with the need for more flexibility and efficiency in client-server communication.
“Think in graphs, not endpoints."
"Describe the data, not the view."
Lessons From 4 Years of GraphQL by Lee Byron, GraphQL Co-Inventor.
What is GraphQL
API standard
declarative data fetching - client can specify exactly what data it needs
single endpoint
Design Principles
Hierarchical
Product‐centric
Strong‐typing
Client‐specified queries
Introspective
Why GraphQL
allow for naturally querying nested information
no more over- and underfetching
n+1 problem
every change that is made to the UI, backend needs to adjusted for the new data needs
insightful analytics
deprecating specific fields that are not requested by any clients any more
GraphQL Schema Definition Language
serve as the contract between the client and the server to define how a client can access the data
frontend teams can mock test their applications by mocking the required data structures
Schema Definition Language
syntax for writing schemas for type system of GraphQL
# ! means required
type Course {
price: Int!
title: String!
}relation
type Course {
price: Int!
title: String!
lectures: [Lecture]!
}
type Lecture {
course: Course!
title: String!
content: String!
}follow the type to query data
GraphQL Operation
Query
in the following example
courses field in the query -> root fields of the query
everything that follows the root field -> payload of the query
return the list of all courses
{
courses {
title
content
}
}Mutation
3 kinds of mutations
creating new data
updating existing data
deleting existing data
Subscription
event-based realtime functionality
hold steady conncetion with server
GraphQL Schema
represents contract between client-server
Reference
https://www.sitepoint.com/silver-bullet-n1-problem/
http://facebook.github.io/graphql
https://www.graphql.com/articles/4-years-of-graphql-lee-byron
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