dataSource: DataSource;

class DataSource {
  constructor(options?: Record<string, any>);

  // 只读属性
  get flowEngine(): FlowEngine;   // 当前 FlowEngine 实例
  get displayName(): string;      // 显示名称（支持 i18n）
  get key(): string;              // 数据源 key，如 'main'
  get name(): string;             // 同 key

  // 数据表读取
  getCollections(): Collection[];                      // 获取所有数据表
  getCollection(name: string): Collection | undefined; // 按名称获取数据表
  getAssociation(associationName: string): CollectionField | undefined; // 获取关联字段（如 users.roles）

  // 数据表管理
  addCollection(collection: Collection | CollectionOptions): void;
  updateCollection(newOptions: CollectionOptions): void;
  upsertCollection(options: CollectionOptions): Collection | undefined;
  upsertCollections(collections: CollectionOptions[], options?: { clearFields?: boolean }): void;
  removeCollection(name: string): void;
  clearCollections(): void;

  // 字段元数据
  getCollectionField(fieldPath: string): CollectionField | undefined;
}

// 获取所有数据表
const collections = ctx.dataSource.getCollections();

// 按名称获取数据表
const users = ctx.dataSource.getCollection('users');
const primaryKey = users?.filterTargetKey ?? 'id';

// 按「数据表.字段路径」获取字段定义（支持关联）
const field = ctx.dataSource.getCollectionField('users.profile.avatar');
const userNameField = ctx.dataSource.getCollectionField('orders.createdBy.name');

// 按 collectionName.fieldName 获取关联字段定义
const rolesField = ctx.dataSource.getAssociation('users.roles');
if (rolesField?.isAssociationField()) {
  const targetCol = rolesField.targetCollection;
  // 按目标数据表结构处理
}

const collections = ctx.dataSource.getCollections();
for (const col of collections) {
  const fields = col.getFields();
  const requiredFields = fields.filter((f) => f.options?.required);
  // ...
}

const field = ctx.dataSource.getCollectionField('users.status');
if (field) {
  const options = field.enum ?? [];
  const operators = field.getFilterOperators();
  // 根据 interface、enum、validation 等做 UI 或校验
}