Changelog - 2025-12-29

Dynamic Binding Registration Fix

Components can now register datasources and controllers during their configure() phase, and those bindings will be properly configured.

Overview

• Simple Fix: Re-run registerDataSources() after registerComponents()
• Future Enhancement: Multi-pass configuration loop for comprehensive dynamic registration

Problem

When components register datasources during configure(), those datasources were never configured because registerDataSources() had already completed.

Initialization Order (Before):

1. registerDataSources() → configures initial datasources
2. registerComponents() → component registers NEW datasource (too late!)
3. registerControllers() → runs normally

The new datasource never gets its configure() called.

Solution (Simple Fix)

File: packages/core/src/base/applications/base.ts

Call registerDataSources() again after registerComponents():

// Before:
await this.registerDataSources();
await this.registerComponents();
await this.registerControllers();

// After:
await this.registerDataSources();
await this.registerComponents();
await this.registerDataSources(); // Re-run for datasources added by components
await this.registerControllers();

Files Changed

Core Package (packages/core)

File	Changes
src/base/applications/base.ts	Added second registerDataSources() call after registerComponents()

No Breaking Changes

All changes are internal. Components that register datasources will now work correctly.

Future Enhancement

For comprehensive dynamic registration support (components registering other components, controllers registering datasources, etc.), a multi-pass configuration loop can be implemented:

Multi-Pass Configuration Loop (Future)

Instead of sequential registration, use a unified loop that continues until no new bindings are discovered:

protected async runConfigurationLoop(): Promise<void> {
  const configured = {
    datasources: new Set<string>(),
    components: new Set<string>(),
    controllers: new Set<string>(),
  };

  let hasNewBindings = true;
  let iteration = 0;
  const MAX_ITERATIONS = 100;

  while (hasNewBindings && iteration < MAX_ITERATIONS) {
    iteration++;
    hasNewBindings = false;

    // Order: datasources -> components -> controllers
    const newDs = await this.configureNewBindings('datasources', configured.datasources);
    const newComp = await this.configureNewBindings('components', configured.components);
    const newCtrl = await this.configureNewBindings('controllers', configured.controllers);

    hasNewBindings = newDs || newComp || newCtrl;
  }
}

Benefits of Multi-Pass:

• Handles arbitrary nesting depth
• Components can register datasources, controllers, or other components
• Datasources configured before components that depend on them
• MAX_ITERATIONS prevents infinite loops from circular dependencies

LoopBack 4 Insights Applied:

• Three-phase execution pattern (configure → discover → load)
• Observer ordering (datasources before components before controllers)
• Stabilization detection (loop until no new bindings)

See full implementation plan in architecture documentation.