angular-modernization

Angular Modernization

Transforms legacy Angular components to modern architecture using a two-step approach:

Automated migrations - Angular CLI schematics for standalone, control flow, and signals Bitwarden patterns - ADR compliance, OnPush change detection, proper visibility, thin components Workflow Step 1: Run Angular CLI Migrations

⚠️ CRITICAL: ALWAYS use Angular CLI migrations when available. DO NOT manually migrate features that have CLI schematics.

Angular provides automated schematics that handle edge cases, update tests, and ensure correctness. Manual migration should ONLY be used for patterns not covered by CLI tools.

IMPORTANT:

Always run the commands using npx ng. All the commands must be run on directories and NOT files. Use the --path option to target directories. Run migrations in order (some depend on others) 1. Standalone Components npx ng generate @angular/core:standalone --path= --mode=convert-to-standalone

NgModule-based → standalone architecture

1. Control Flow Syntax npx ng generate @angular/core:control-flow

ngIf, ngFor, *ngSwitch → @if, @for, @switch

1. Signal Inputs npx ng generate @angular/core:signal-input-migration

@Input() → signal inputs

1. Signal Outputs npx ng generate @angular/core:output-migration

@Output() → signal outputs

1. Signal Queries npx ng generate @angular/core:signal-queries-migration

@ViewChild, @ContentChild, etc. → signal queries

1. inject() Function npx ng generate @angular/core:inject-migration

Constructor injection → inject() function

1. Self-Closing Tag npx ng generate @angular/core:self-closing-tag

Updates templates to self-closing syntax

1. Unused Imports npx ng generate @angular/core:unused-imports

Removes unused imports

Step 2: Apply Bitwarden Patterns

See migration-patterns.md for detailed examples.

Add OnPush change detection Apply visibility modifiers (protected for template access, private for internal) Convert local component state to signals Keep service observables (don't convert to signals) Extract business logic to services Organize class members correctly Update tests for standalone Step 3: Validate Fix linting and formatting using npm run lint:fix Run tests using npm run test

If any errors occur, fix them accordingly.

Key Decisions Signals vs Observables Signals - Component-local state only (ADR-0027) Observables - Service state and cross-component communication (ADR-0003) Use toSignal() to bridge observables into signal-based components Visibility protected - Template-accessible members private - Internal implementation Other Rules Always add OnPush change detection No TypeScript enums (use const objects with type aliases per ADR-0025) No code regions (refactor instead) Thin components (business logic in services) Validation Checklist

Before completing migration:

OnPush change detection added Visibility modifiers applied (protected/private) Signals for component state, observables for service state Class members organized (see migration-patterns.md) Tests updated and passing No new TypeScript enums No code regions References Bitwarden ADRs ADR-0003: Observable Data Services ADR-0025: No TypeScript Enums ADR-0027: Angular Signals Bitwarden Angular Style Guide Angular Resources Angular Style Guide Angular Migrations Angular CLI Schematics