21. FAQ 2 - GraphQL - API for beginners

Graph Querry Language GraphQL

What is GraphQL?

GraphQL is an open-source query language. GraphQL is an answer to problems that REST API has:

a lot of endpoints;
it is harder for developers to learn and understand your API;
there is over- and under-fetching of information.

Who created GraphQL?

To solve above mention problems Facebook created GraphQL.

How GraphQL works?

What are queries and mutations?

A GraphQL operation can either be:

Read operation, known as Query, is used to read or fetch values
Write operation, known as Mutation, is used to write or delete values.

What is a schema?

A schema is a key concept and collection of GraphQL types. ISchema defines how the client can request the data.

What are resolvers?

Resolver is a function that generates responses for GraphQL queries & mutations. Then, the resolver returns the results wrapped by a callable function.

What is the role of the developer?

Create a schema for allowed document fields and field types
Create and implement a resolver to return corresponding data.

Advantages

A GraphQL schema sets a single source of truth in a GraphQL application.
GraphQL calls are handled in a single round trip.
Miscommunication between the client and the server is reduced.
GraphQL is introspective. This is ideal for auto-generating documentation.
GraphQL extensions offer features not available with REST APIs.
GraphQL can be introduced on top of an existing REST API.

Disadvantages

GraphQL presents a learning curve for developers familiar with REST APIs.
GraphQL shifts much of the work of a data query to the server side, which adds complexity for server developers.
Depending on how it is implemented, GraphQL might require different API management strategies than REST APIs, particularly when considering rate limits and pricing.
Caching is more complex than REST.
API maintainers have the additional task of writing maintainable GraphQL schema.