Update Lifecycle (onchanges -> afterchanges)

examples/ng/doc/lifecycle-hooks/lib/app_component.dart

@@ -4,7 +4,7 @@ import 'src/after_content_component.dart';
 import 'src/after_view_component.dart';
 import 'src/counter_component.dart';
 import 'src/do_check_component.dart';
-import 'src/on_changes_component.dart';
+import 'src/after_changes_component.dart';
 import 'src/peek_a_boo_parent_component.dart';
 import 'src/spy_component.dart';
 
@@ -16,7 +16,7 @@ import 'src/spy_component.dart';
     AfterViewParentComponent,
     CounterParentComponent,
     DoCheckParentComponent,
-    OnChangesParentComponent,
+    AfterChangesParentComponent,
     PeekABooParentComponent,
     SpyParentComponent,
   ],

examples/ng/doc/lifecycle-hooks/lib/app_component.html

@@ -1,12 +1,12 @@
 <a id="top"></a>
 <h1>Component Lifecycle Hooks</h1>
 <a href="#hooks">Peek-a-boo: (most) lifecycle hooks</a><br>
-<a href="#onchanges">OnChanges</a><br>
+<a href="#afterchanges">AfterChanges</a><br>
 <a href="#docheck">DoCheck</a><br>
 <a href="#after-view">AfterViewInit & AfterViewChecked</a><br>
 <a href="#after-content">AfterContentInit & AfterContentChecked</a><br>
 <a href="#spy">Spy: directive with OnInit & OnDestroy</a><br>
-<a href="#counter">Counter: OnChanges + Spy directive</a><br>
+<a href="#counter">Counter: AfterChanges + Spy directive</a><br>
 
 <a id="hooks"></a>
 <peek-a-boo-parent></peek-a-boo-parent>
@@ -16,8 +16,8 @@ <h1>Component Lifecycle Hooks</h1>
 <spy-parent></spy-parent>
 <a href="#top">back to top</a>
 
-<a id="onchanges"></a>
-<on-changes-parent></on-changes-parent>
+<a id="afterchanges"></a>
+<after-changes-parent></after-changes-parent>
 <a href="#top">back to top</a>
 
 <a id="docheck"></a>

examples/ng/doc/lifecycle-hooks/lib/src/on_changes_component.dart → examples/ng/doc/lifecycle-hooks/lib/src/after_changes_component.dart

@@ -1,5 +1,3 @@
-import 'dart:convert';
-
 import 'package:angular/angular.dart';
 import 'package:angular_forms/angular_forms.dart';
 
@@ -10,7 +8,7 @@ class Hero {
 }
 
 @Component(
-  selector: 'on-changes',
+  selector: 'after-changes',
   template: '''
     <div class="hero">
       <p>{{hero.name}} can {{power}}</p>
@@ -25,47 +23,41 @@ class Hero {
   ],
   directives: [coreDirectives],
 )
-class OnChangesComponent implements OnChanges {
+class AfterChangesComponent implements AfterChanges {
   // #docregion inputs
   @Input()
-  Hero hero;
+  late Hero hero;
   @Input()
-  String power;
+  late String power;
   // #enddocregion inputs
 
   List<String> changeLog = [];
 
-  // #docregion ng-on-changes
-  ngOnChanges(Map<String, SimpleChange> changes) {
-    changes.forEach((String propName, SimpleChange change) {
-      String cur = json.encode(change.currentValue);
-      String prev = change.previousValue == null
-          ? "{}"
-          : json.encode(change.previousValue);
-      changeLog.add('$propName: currentValue = $cur, previousValue = $prev');
-    });
+  // #docregion ng-after-changes
+  ngAfterChanges() {
+    changeLog.add('Input property has changed.');
   }
-  // #enddocregion ng-on-changes
+  // #enddocregion ng-after-changes
 
   void reset() {
     changeLog.clear();
   }
 }
 
 @Component(
-  selector: 'on-changes-parent',
-  templateUrl: 'on_changes_parent_component.html',
+  selector: 'after-changes-parent',
+  templateUrl: 'after_changes_parent_component.html',
   styles: ['.parent {background: Lavender}'],
-  directives: [coreDirectives, formDirectives, OnChangesComponent],
+  directives: [coreDirectives, formDirectives, AfterChangesComponent],
 )
-class OnChangesParentComponent {
-  Hero hero;
-  String power;
-  String title = 'OnChanges';
-  @ViewChild(OnChangesComponent)
-  OnChangesComponent childView;
+class AfterChangesParentComponent {
+  late Hero hero;
+  late String power;
+  String title = 'AfterChanges';
+  @ViewChild(AfterChangesComponent)
+  AfterChangesComponent? childView;
 
-  OnChangesParentComponent() {
+  AfterChangesParentComponent() {
     reset();
   }
 

examples/ng/doc/lifecycle-hooks/lib/src/on_changes_parent_component.html → examples/ng/doc/lifecycle-hooks/lib/src/after_changes_parent_component.html

@@ -7,7 +7,7 @@ <h2>{{title}}</h2>
   </table>
   <p><button (click)="reset()">Reset Log</button></p>
 
-  <!-- #docregion on-changes -->
-  <on-changes [hero]="hero" [power]="power"></on-changes>
-  <!-- #enddocregion on-changes -->
+  <!-- #docregion after-changes -->
+  <after-changes [hero]="hero" [power]="power"></after-changes>
+  <!-- #enddocregion after-changes -->
 </div>

examples/ng/doc/lifecycle-hooks/lib/src/after_content_component.dart

@@ -28,12 +28,12 @@ class ChildComponent {
 )
 // #docregion hooks
 class AfterContentComponent implements AfterContentChecked, AfterContentInit {
-  String _prevHero = '';
+  String? _prevHero = '';
   String comment = '';
 
   // Query for a CONTENT child of type `ChildComponent`
   @ContentChild(ChildComponent)
-  ChildComponent contentChild;
+  ChildComponent? contentChild;
 
   // #enddocregion hooks
   final LoggerService _logger;
@@ -64,7 +64,8 @@ class AfterContentComponent implements AfterContentChecked, AfterContentInit {
   // #docregion do-something
   /// This surrogate for real business logic; sets the `comment`
   void _doSomething() {
-    comment = contentChild.hero.length > 10 ? "That's a long name" : '';
+    final length = contentChild?.hero.length ?? 0;
+    comment = length > 10 ? "That's a long name" : '';
   }
   // #enddocregion do-something
 

examples/ng/doc/lifecycle-hooks/lib/src/after_view_component.dart

@@ -29,11 +29,11 @@ class ChildViewComponent {
 )
 // #docregion hooks
 class AfterViewComponent implements AfterViewChecked, AfterViewInit {
-  var _prevHero = '';
+  String? _prevHero = '';
 
   // Query for a VIEW child of type `ChildViewComponent`
   @ViewChild(ChildViewComponent)
-  ChildViewComponent viewChild;
+  ChildViewComponent? viewChild;
 
   // #enddocregion hooks
   final LoggerService _logger;
@@ -51,10 +51,10 @@ class AfterViewComponent implements AfterViewChecked, AfterViewInit {
 
   ngAfterViewChecked() {
     // viewChild is updated after the view has been checked
-    if (_prevHero == viewChild.hero) {
+    if (_prevHero == viewChild?.hero) {
       _logIt('AfterViewChecked (no change)');
     } else {
-      _prevHero = viewChild.hero;
+      _prevHero = viewChild?.hero;
       _logIt('AfterViewChecked');
       _doSomething();
     }
@@ -66,7 +66,8 @@ class AfterViewComponent implements AfterViewChecked, AfterViewInit {
   // #docregion do-something
   // This surrogate for real business logic sets the `comment`
   void _doSomething() {
-    var c = viewChild.hero.length > 10 ? "That's a long name" : '';
+    var length = viewChild?.hero.length ?? 0;
+    var c = length > 10 ? "That's a long name" : '';
     if (c != comment) {
       // Wait a tick because the component's view has already been checked
       _logger.tick().then((_) {

examples/ng/doc/lifecycle-hooks/lib/src/counter_component.dart

@@ -16,23 +16,20 @@ import 'spy_directive.dart';
   styles: ['.counter {background: LightYellow; padding: 8px; margin-top: 8px}'],
   directives: [coreDirectives, SpyDirective],
 )
-class MyCounterComponent implements OnChanges {
+class MyCounterComponent implements AfterChanges {
   @Input()
-  num counter;
+  num counter = 0;
   List<String> changeLog = [];
 
-  ngOnChanges(Map<String, SimpleChange> changes) {
+  ngAfterChanges() {
     // Empty the changeLog whenever counter goes to zero
     // hint: this is a way to respond programmatically to external value changes.
     if (this.counter == 0) {
       changeLog.clear();
     }
 
-    // A change to `counter` is the only change we care about
-    SimpleChange chng = changes['counter'];
-    var cur = chng.currentValue;
-    var prev = chng.previousValue == null ? "{}" : chng.previousValue;
-    changeLog.add('counter: currentValue = $cur, previousValue = $prev');
+    // A change to `counter` is the only change we can get.
+    changeLog.add('counter changed to $counter');
   }
 }
 
@@ -57,7 +54,7 @@ class MyCounterComponent implements OnChanges {
 )
 class CounterParentComponent {
   final LoggerService _logger;
-  num value;
+  num value = 0;
 
   CounterParentComponent(this._logger) {
     reset();

examples/ng/doc/lifecycle-hooks/lib/src/do_check_component.dart

@@ -25,9 +25,9 @@ class Hero {
 )
 class DoCheckComponent implements DoCheck {
   @Input()
-  Hero hero;
+  late Hero hero;
   @Input()
-  String power;
+  late String power;
 
   bool changeDetected = false;
   List<String> changeLog = [];
@@ -87,11 +87,11 @@ class DoCheckComponent implements DoCheck {
   directives: [coreDirectives, formDirectives, DoCheckComponent],
 )
 class DoCheckParentComponent {
-  Hero hero;
-  String power;
+  late Hero hero;
+  late String power;
   String title = 'DoCheck';
   @ViewChild(DoCheckComponent)
-  DoCheckComponent childView;
+  DoCheckComponent? childView;
 
   DoCheckParentComponent() {
     reset();

examples/ng/doc/lifecycle-hooks/lib/src/peek_a_boo_component.dart

@@ -33,7 +33,7 @@ class PeekABoo implements OnInit {
 // unless we want typing and tool support.
 class PeekABooComponent extends PeekABoo
     implements
-        OnChanges,
+        AfterChanges,
         OnInit,
         DoCheck,
         AfterContentInit,
@@ -42,31 +42,20 @@ class PeekABooComponent extends PeekABoo
         AfterViewChecked,
         OnDestroy {
   @Input()
-  String name;
+  String? name;
 
   int _afterContentCheckedCounter = 1;
   int _afterViewCheckedCounter = 1;
-  int _onChangesCounter = 1;
-  String _verb = 'initialized';
+  int _afterChangesCounter = 1;
 
   PeekABooComponent(LoggerService logger) : super(logger) {
     var _is = name != null ? 'is' : 'is not';
     _logIt('name $_is known at construction');
   }
 
   // Only called if there is an @input variable set by parent.
-  void ngOnChanges(Map<String, SimpleChange> changes) {
-    List<String> messages = [];
-    changes.forEach((String propName, SimpleChange change) {
-      if (propName == 'name') {
-        var name = changes['name'].currentValue;
-        messages.add('name $_verb to "$name"');
-      } else {
-        messages.add('$propName $_verb');
-      }
-    });
-    _logIt('OnChanges (${_onChangesCounter++}): ${messages.join('; ')}');
-    _verb = 'changed'; // Next time it will be a change
+  void ngAfterChanges() {
+    _logIt('AfterChanges (${_afterChangesCounter++})');
   }
 
   // Beware! Called frequently!