Resolvers and Subscriptions

Welcome to the world of GraphQL resolvers in NestJS! Resolvers are the core of your GraphQL API, acting as the bridge between your GraphQL schema and your application's data sources.

• They define how to fetch the data for a specific field in your schema.
• Think of them as functions that execute when a corresponding field is requested in a GraphQL query or mutation.
• Resolvers can interact with databases, REST APIs, or any other data source.

NestJS simplifies resolver creation using decorators. You define a class as a resolver and then use specific decorators for different GraphQL operations:

• @Resolver(): Marks a class as a GraphQL resolver.
• @Query(): Maps a method to a GraphQL query operation (data fetching).
• @Mutation(): Maps a method to a GraphQL mutation operation (data modification).
• @Subscription(): Maps a method to a GraphQL subscription operation (real-time data).