Folder structure

A database first BFF should have the following structure:

• Query: code related to making queries (getting data)
• Command: code related to making commands (a change)
• Infra: infra related code (servers, models, etc)
• Utils: general tools/shared code
• Listener: mappers for events that the BFF is consuming
• Trigger: rules for events that the BFF is publishing

Query folder (src/query)

The query folder holds the code related to making queries. Below details the structure.

Query folder example structure

- query
  - initApplication.ts
  - getSomething
    - index.ts: exports getSomethingController
    - return-type.ts: exports GetSomethingReturnType
  - getSomethingElse
    - index.ts: exports getSomethingElseController
    - return-type.ts: exports GetSomethingElseReturnType

initApplication.ts (src/query/initApplication)

This file is responsible for initializing the application container.

A folder for each query resolver

Each graphql query resolver should have its own resolver. For example, take a look at the following queries in the resolver:

type Input<T> = { input: T }

export const resolvers = {
  Query: {
    getSomething: (_: DocumentNode, { input }: Input<{ id: string }>) => {
      return getPostController(input.id)
    },
    getSomethingElse: (_: DocumentNode, { input }: Input<{ id: string }>) => {
      return getUserPostsController(input.id)
    }
  }
  ...
}

Each of the above queries should have it's own folder:

• src/query/getSomething
• src/query/getSomethingElse

Each folder should have the following files:

• index.ts - the controller for the query
• return-type.ts - the return type of the query