Introduction
GraphQL Modules is a utility library, allowing you separate your GraphQL schema implementation into small, reusable, easy-to-implement and easy-to-test pieces.
In GraphQL Modules, each module has its own GraphQL type definitions and resolvers implementations.
The idea behind this is to implement the Separation of Concerns design pattern in GraphQL and to allow you to write simple modules that only do what they need to. This way, they're easier to write, maintain and test.
During development, GraphQL-Modules allow you to separate your GraphQL schema definitions, while in runtime, you'll be able to serve a unified schema.
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StructureEach GraphQL module
is built using the basics of GraphQL:
- Type definitions
- Resolver functions
As your application grows, modules can use Dependency Injection, if you wish to separate your resolvers and your business-logic.
The structure of GraphQL API with GraphQL Modules is flat. Module
s are on the same level and there's Application
on top of them.
#
ExampleTo get a better understanding of the structure and extensibility of modules, let's make an example app with four modules:
- User (define what a user in our app should have)
- Authentication (define only what is needed to authenticate users)
- Profile (define a user's profile)
- Gallery (define a user's photo gallery)
Let's understand how to define each module's schema and how to separate it into smaller pieces.
Each one of our modules, contributes small part of the schema, and the GraphQL Application
merged it into a complete schema.
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User ModuleThis module allows querying users by id and defines only the very basic fields.
#
Authentication ModuleThis module declares the authentication basics in Mutation
, Query
and User
types.
#
Profile ModuleThe profile module declares the Profile
type and adds the profile
field to User
:
#
Gallery ModuleThe gallery module is similar to the profile
module. It declares only the parts of the schema that are required by the gallery feature: