The backend directory structure is as follows:

server
  └───ability
  └───constants 
  └───core
  └───database
  └───decorators
  └───filters
  └───guards
  └───health
  └───integrations
  └───metadata
  └───workspace
  └───utils

Ability

Defines permissions and includes handlers for each entity.

Decorators

Defines custom decorators in NestJS for added functionality.

See custom decorators for more details.

Filters

Includes exception filters to handle exceptions that might occur in GraphQL endpoints.

Guards

See guards for more details.

Health

Includes a publicly available REST API (healthz) that returns a JSON to confirm whether the database is working as expected.

Metadata

Defines custom objects and makes available a GraphQL API (graphql/metadata).

Workspace

Generates and serves custom GraphQL schema based on the metadata.

Workspace Directory Structure

workspace

  └───workspace-schema-builder
    └───factories 
    └───graphql-types
    └───database
    └───interfaces
    └───object-definitions
    └───services
    └───storage
    └───utils
  └───workspace-resolver-builder
    └───factories
    └───interfaces
  └───workspace-query-builder
    └───factories
    └───interfaces
  └───workspace-query-runner
    └───interfaces
    └───utils 
  └───workspace-datasource
  └───workspace-manager
  └───workspace-migration-runner
  └───utils 
  └───workspace.module.ts   
  └───workspace.factory.spec.ts    
  └───workspace.factory.ts      

The root of the workspace directory includes the workspace.factory.ts, a file containing the createGraphQLSchema function. This function generates workspace-specific schema by using the metadata to tailor a schema for individual workspaces. By separating the schema and resolver construction, we use the makeExecutableSchema function, which combines these discrete elements.

This strategy is not just about organization, but also helps with optimization, such as caching generated type definitions to enhance performance and scalability.

Workspace Schema builder

Generates the GraphQL schema, and includes:

Factories:

Specialised constructors to generate GraphQL-related constructs.

• The type.factory translates field metadata into GraphQL types using TypeMapperService.
• The type-definition.factory creates GraphQL input or output objects derived from objectMetadata.

GraphQL Types

Includes enumerations, inputs, objects, and scalars, and serves as the building blocks for the schema construction.

Interfaces and Object Definitions

Contains the blueprints for GraphQL entities, and includes both predefined and custom types like MONEY or URL.

Services

Contains the service responsible for associating FieldMetadataType with its appropriate GraphQL scalar or query modifiers.

Storage

Includes the TypeDefinitionsStorage class that contains reusable type definitions, preventing duplication of GraphQL types.

Workspace Resolver Builder

Creates resolver functions for querying and mutating the GraphQL schema.

Each factory in this directory is responsible for producing a distinct resolver type, such as the FindManyResolverFactory, designed for adaptable application across various tables.

Workspace Query Runner

Runs the generated queries on the database and parses the result.