@constructive-io/express-context

@constructive-io/express-context

Extractable Express middleware for Constructive tenant context — domain resolution, JWT auth, pgSettings, withPgClient, and modular per-database cached lookups.

Usage

import {
  createContextMiddleware,
  requestIdMiddleware,
  createDefaultRegistry,
} from '@constructive-io/express-context';

const loaders = createDefaultRegistry();

const app = express();

app.use(requestIdMiddleware());
app.use(apiMiddleware);            // sets req.api
app.use(authMiddleware);           // sets req.token
app.use(createContextMiddleware({ loaders })); // builds req.constructive

app.post('/v1/chat', async (req, res) => {
  const ctx = req.constructive;
  const rls = await ctx.useModule('rlsModule');       // only fires if not cached
  const auth = await ctx.useModule('authSettings');    // only fires if not cached
  // webauthnSettings loader never fires if nobody asks for it

  const result = await ctx.withPgClient(async (client) => {
    return client.query('SELECT current_user_id()');
  });

  res.json(result.rows);
});

What it provides

• Types — ApiStructure, RlsModule, AuthSettings, ConstructiveContext, etc.
• pgSettings builder — Constructs SET LOCAL key-value pairs from API + token
• withPgClient — Tenant-scoped RLS transaction helper (BEGIN → SET LOCAL → fn → COMMIT)
• requestId middleware — UUID correlation ID (from X-Request-Id header or generated)
• Context middleware — Composes all of the above into req.constructive
• Module loaders — Pluggable per-database cached lookups with lazy on-demand resolution

Module Loaders

Each loader encapsulates a SQL query + type transform + per-databaseId LRU cache for one piece of per-database configuration. Loaders are registered in a LoaderRegistry and resolved lazily via useModule(name).

Built-in loaders

Loader	Source	Description
rlsLoader	services_public.rls_settings	RLS module (authenticate functions, schema refs)
corsLoader	services_public.cors_settings	CORS allowed origins
databaseSettingsLoader	services_public.database_settings	Feature flags (aggregates, search, uploads, etc.)
pubkeyLoader	services_public.pubkey_settings	Public key challenge auth settings
webauthnLoader	services_public.webauthn_settings	WebAuthn/passkey configuration
authSettingsLoader	metaschema_modules_public.sessions_module	Cookie/captcha settings (two-step tenant DB discovery)

Custom loaders

import { createModuleLoader, createLoaderRegistry } from '@constructive-io/express-context';

const myLoader = createModuleLoader({
  name: 'myModule',
  ttlMs: 60_000,
  async resolve(ctx) {
    const { rows } = await ctx.tenantPool.query(MY_SQL, [ctx.databaseId]);
    return rows[0] ? transform(rows[0]) : undefined;
  },
});

const registry = createLoaderRegistry();
registry.register(myLoader);

---

Education and Tutorials

1. Quickstart: Getting Up and Running Get started with modular databases in minutes. Install prerequisites and deploy your first module.

2. Modular PostgreSQL Development with Database Packages Learn to organize PostgreSQL projects with pgpm workspaces and reusable database modules.

3. Authoring Database Changes Master the workflow for adding, organizing, and managing database changes with pgpm.

4. End-to-End PostgreSQL Testing with TypeScript Master end-to-end PostgreSQL testing with ephemeral databases, RLS testing, and CI/CD automation.

5. Supabase Testing Use TypeScript-first tools to test Supabase projects with realistic RLS, policies, and auth contexts.

6. Drizzle ORM Testing Run full-stack tests with Drizzle ORM, including database setup, teardown, and RLS enforcement.

7. Troubleshooting Common issues and solutions for pgpm, PostgreSQL, and testing.

Related Constructive Tooling

Package Management

• pgpm: PostgreSQL Package Manager for modular Postgres development. Works with database workspaces, scaffolding, migrations, seeding, and installing database packages.

Testing

• pgsql-test: Isolated testing environments with per-test transaction rollbacks—ideal for integration tests, complex migrations, and RLS simulation.
• pgsql-seed: PostgreSQL seeding utilities for CSV, JSON, SQL data loading, and pgpm deployment.
• supabase-test: Supabase-native test harness preconfigured for the local Supabase stack—per-test rollbacks, JWT/role context helpers, and CI/GitHub Actions ready.
• graphile-test: Authentication mocking for Graphile-focused test helpers and emulating row-level security contexts.
• pg-query-context: Session context injection to add session-local context (e.g., SET LOCAL) into queries—ideal for setting role, jwt.claims, and other session settings.

Parsing & AST

• pgsql-parser: SQL conversion engine that interprets and converts PostgreSQL syntax.
• libpg-query-node: Node.js bindings for libpg_query, converting SQL into parse trees.
• pg-proto-parser: Protobuf parser for parsing PostgreSQL Protocol Buffers definitions to generate TypeScript interfaces, utility functions, and JSON mappings for enums.
• @pgsql/enums: TypeScript enums for PostgreSQL AST for safe and ergonomic parsing logic.
• @pgsql/types: Type definitions for PostgreSQL AST nodes in TypeScript.
• @pgsql/utils: AST utilities for constructing and transforming PostgreSQL syntax trees.

Documentation & Skills

• constructive-skills: Platform documentation and AI agent skills — feature catalog, blueprint reference, SDK guides (i18n, billing, limits, events, uploads, security, entities, search, AI), and deployment guides.

Install skills for AI coding agents:

# All platform skills (security, blueprints, codegen, billing, etc.)
npx skills add constructive-io/constructive-skills

# Individual repo skills (pgpm, testing, CLI, search, etc.)
npx skills add https://github.com/constructive-io/constructive --skill pgpm
npx skills add https://github.com/constructive-io/constructive --skill constructive-testing

Credits

Built by the Constructive team — creators of modular Postgres tooling for secure, composable backends. If you like our work, contribute on GitHub.

Disclaimer

AS DESCRIBED IN THE LICENSES, THE SOFTWARE IS PROVIDED "AS IS", AT YOUR OWN RISK, AND WITHOUT WARRANTIES OF ANY KIND.

No developer or entity involved in creating this software will be liable for any claims or damages whatsoever associated with your use, inability to use, or your interaction with other users of the code, including any direct, indirect, incidental, special, exemplary, punitive or consequential damages, or loss of profits, cryptocurrencies, tokens, or anything else of value.