Define Types

GraphQL types in Base are classes. Each @GqlField becomes a schema field; the SDL is generated from what you write, so schema and code cannot drift.

Object types

import { GqlField } from '@system-inc/base-foundation/graphql/decorators/GqlField';
import { GqlObjectType } from '@system-inc/base-foundation/graphql/decorators/GqlObjectType';

@GqlObjectType()
export class Note {
    @GqlField(() => String)
    id: string;

    @GqlField(() => String)
    title: string;

    @GqlField(() => String, { nullable: true })
    summary: string | null;

    @GqlField(() => [String])
    tags: string[];
}

• The thunk (() => String) declares the GraphQL type; arrays use () => [Type].
• Nullability must match the TypeScript type — { nullable: true } pairs with | null, and Base's gql-nullable-parity lint rule enforces the agreement. The schema never promises more than the types do.
• Unlike ORM entities, GraphQL type classes are plain: no declare, no base class.

Input types

Inputs get their own decorator, and can carry validation, which runs before your resolver sees the data:

import { GqlInputType } from '@system-inc/base-foundation/graphql/decorators/GqlInputType';
import { VerifyIsNotEmpty } from '@system-inc/base-foundation/validation/decorators/VerifyIsNotEmpty';

@GqlInputType('CreateNoteInput')
export class CreateNoteInput {
    @VerifyIsNotEmpty()
    @GqlField(() => String)
    title: string;

    @GqlField(() => String)
    content: string;
}

The argument to @GqlInputType is the schema name. A single class can even serve as both shapes — stack @GqlObjectType() and @GqlInputType('TesterInput') on one class when the output and input shapes genuinely coincide.

Nesting

Fields reference other type classes through the same thunk form:

@GqlObjectType()
export class NoteWithAuthor {
    @GqlField(() => Note)
    note: Note;

    @GqlField(() => Author)
    author: Author;
}

The generated schema mirrors the class graph. When you're ready to serve these types, head to Write Resolvers.