From 4456905d9cfcc3535ddcd6dc09017b5850168e97 Mon Sep 17 00:00:00 2001
From: Andrew Scott <atscott@google.com>
Date: Tue, 7 May 2024 15:00:10 -0700
Subject: [PATCH] fix(forms): Make `NgControlStatus` host bindings `OnPush`
 compatible

This commit makes the host bindings of `NgControlStatus[Group]`
compatible with `OnPush` components. Note that this intentionally _does not_
expose any new APIs in the forms module. The goal is only to remove
unpreventable `ExpressionChangedAfterItHasBeenCheckedError` in the forms
code that developers do not have control over.
---
 .../forms/src/directives/ng_control_status.ts | 11 ++++++++
 packages/forms/src/directives/ng_form.ts      |  5 ++++
 .../form_group_directive.ts                   |  9 ++++--
 packages/forms/src/model/abstract_model.ts    | 28 ++++++++++++++++++-
 4 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/packages/forms/src/directives/ng_control_status.ts b/packages/forms/src/directives/ng_control_status.ts
index ca9a9b2c5a2b82..a9de3185aa5cd7 100644
--- a/packages/forms/src/directives/ng_control_status.ts
+++ b/packages/forms/src/directives/ng_control_status.ts
@@ -26,6 +26,8 @@ export class AbstractControlStatus {
   }
 
   protected get isTouched() {
+    // track the touched signal
+    this._cd?.control?._touched?.();
     return !!this._cd?.control?.touched;
   }
 
@@ -34,26 +36,35 @@ export class AbstractControlStatus {
   }
 
   protected get isPristine() {
+    // track the pristine signal
+    this._cd?.control?._pristine?.();
     return !!this._cd?.control?.pristine;
   }
 
   protected get isDirty() {
+    // pristine signal already tracked above
     return !!this._cd?.control?.dirty;
   }
 
   protected get isValid() {
+    // track the status signal
+    this._cd?.control?._status?.();
     return !!this._cd?.control?.valid;
   }
 
   protected get isInvalid() {
+    // status signal already tracked above
     return !!this._cd?.control?.invalid;
   }
 
   protected get isPending() {
+    // status signal already tracked above
     return !!this._cd?.control?.pending;
   }
 
   protected get isSubmitted() {
+    // track the submitted signal
+    (this._cd as Writable<NgForm | FormGroupDirective> | null)?._submitted?.();
     // We check for the `submitted` field from `NgForm` and `FormGroupDirective` classes, but
     // we avoid instanceof checks to prevent non-tree-shakable references to those types.
     return !!(this._cd as Writable<NgForm | FormGroupDirective> | null)?.submitted;
diff --git a/packages/forms/src/directives/ng_form.ts b/packages/forms/src/directives/ng_form.ts
index aa759817653bfc..4d740c764b65fe 100644
--- a/packages/forms/src/directives/ng_form.ts
+++ b/packages/forms/src/directives/ng_form.ts
@@ -16,6 +16,7 @@ import {
   Optional,
   Provider,
   Self,
+  signal,
   ɵWritable as Writable,
 } from '@angular/core';
 
@@ -127,6 +128,8 @@ export class NgForm extends ControlContainer implements Form, AfterViewInit {
    * Returns whether the form submission has been triggered.
    */
   public readonly submitted: boolean = false;
+  /** @internal */
+  readonly _submitted = signal(false);
 
   private _directives = new Set<NgModel>();
 
@@ -328,6 +331,7 @@ export class NgForm extends ControlContainer implements Form, AfterViewInit {
    */
   onSubmit($event: Event): boolean {
     (this as Writable<this>).submitted = true;
+    this._submitted.set(true);
     syncPendingControls(this.form, this._directives);
     this.ngSubmit.emit($event);
     // Forms with `method="dialog"` have some special behavior
@@ -352,6 +356,7 @@ export class NgForm extends ControlContainer implements Form, AfterViewInit {
   resetForm(value: any = undefined): void {
     this.form.reset(value);
     (this as Writable<this>).submitted = false;
+    this._submitted.set(false);
   }
 
   private _setUpdateStrategy() {
diff --git a/packages/forms/src/directives/reactive_directives/form_group_directive.ts b/packages/forms/src/directives/reactive_directives/form_group_directive.ts
index 835191c914e597..211892aacab358 100644
--- a/packages/forms/src/directives/reactive_directives/form_group_directive.ts
+++ b/packages/forms/src/directives/reactive_directives/form_group_directive.ts
@@ -18,6 +18,7 @@ import {
   Output,
   Provider,
   Self,
+  signal,
   SimpleChanges,
   ɵWritable as Writable,
 } from '@angular/core';
@@ -87,10 +88,12 @@ export class FormGroupDirective extends ControlContainer implements Form, OnChan
    * Reports whether the form submission has been triggered.
    */
   public readonly submitted: boolean = false;
+  /** @internal */
+  readonly _submitted = signal(false);
 
   /**
-   * Reference to an old form group input value, which is needed to cleanup old instance in case it
-   * was replaced with a new one.
+   * Reference to an old form group input value, which is needed to cleanup
+   * old instance in case it was replaced with a new one.
    */
   private _oldForm: FormGroup | undefined;
 
@@ -300,6 +303,7 @@ export class FormGroupDirective extends ControlContainer implements Form, OnChan
    */
   onSubmit($event: Event): boolean {
     (this as Writable<this>).submitted = true;
+    this._submitted.set(true);
     syncPendingControls(this.form, this.directives);
     this.ngSubmit.emit($event);
     // Forms with `method="dialog"` have some special behavior that won't reload the page and that
@@ -325,6 +329,7 @@ export class FormGroupDirective extends ControlContainer implements Form, OnChan
   resetForm(value: any = undefined): void {
     this.form.reset(value);
     (this as Writable<this>).submitted = false;
+    this._submitted.set(false);
   }
 
   /** @internal */
diff --git a/packages/forms/src/model/abstract_model.ts b/packages/forms/src/model/abstract_model.ts
index 1c185c7c2f04d2..ab6d4f26ca98f6 100644
--- a/packages/forms/src/model/abstract_model.ts
+++ b/packages/forms/src/model/abstract_model.ts
@@ -6,7 +6,12 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {EventEmitter, ɵRuntimeError as RuntimeError, ɵWritable as Writable} from '@angular/core';
+import {
+  EventEmitter,
+  signal,
+  ɵRuntimeError as RuntimeError,
+  ɵWritable as Writable,
+} from '@angular/core';
 import {Observable, Subject} from 'rxjs';
 
 import {
@@ -569,6 +574,8 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
    * both valid AND invalid or invalid AND disabled.
    */
   public readonly status!: FormControlStatus;
+  /** @internal */
+  readonly _status = signal<FormControlStatus | null>(null);
 
   /**
    * A control is `valid` when its `status` is `VALID`.
@@ -649,6 +656,9 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
    */
   public readonly pristine: boolean = true;
 
+  /** @internal */
+  readonly _pristine = signal(true);
+
   /**
    * A control is `dirty` if the user has changed the value
    * in the UI.
@@ -668,6 +678,9 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
    */
   public readonly touched: boolean = false;
 
+  /** @internal */
+  readonly _touched = signal(false);
+
   /**
    * True if the control has not been marked as touched
    *
@@ -933,6 +946,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   ): void {
     const changed = this.touched === false;
     (this as Writable<this>).touched = true;
+    this._touched.set(this.touched);
 
     const sourceControl = opts.sourceControl ?? this;
     if (this._parent && !opts.onlySelf) {
@@ -993,6 +1007,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   ): void {
     const changed = this.touched === true;
     (this as Writable<this>).touched = false;
+    this._touched.set(this.touched);
     this._pendingTouched = false;
 
     const sourceControl = opts.sourceControl ?? this;
@@ -1039,6 +1054,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   ): void {
     const changed = this.pristine === true;
     (this as Writable<this>).pristine = false;
+    this._pristine.set(false);
 
     const sourceControl = opts.sourceControl ?? this;
     if (this._parent && !opts.onlySelf) {
@@ -1083,6 +1099,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   ): void {
     const changed = this.pristine === false;
     (this as Writable<this>).pristine = true;
+    this._pristine.set(true);
     this._pendingDirty = false;
 
     const sourceControl = opts.sourceControl ?? this;
@@ -1130,6 +1147,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
     opts: {onlySelf?: boolean; emitEvent?: boolean; sourceControl?: AbstractControl} = {},
   ): void {
     (this as Writable<this>).status = PENDING;
+    this._status.set(PENDING);
 
     const sourceControl = opts.sourceControl ?? this;
     if (opts.emitEvent !== false) {
@@ -1172,6 +1190,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
     const skipPristineCheck = this._parentMarkedDirty(opts.onlySelf);
 
     (this as Writable<this>).status = DISABLED;
+    this._status.set(DISABLED);
     (this as Writable<this>).errors = null;
     this._forEachChild((control: AbstractControl) => {
       /** We don't propagate the source control downwards */
@@ -1215,6 +1234,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
     const skipPristineCheck = this._parentMarkedDirty(opts.onlySelf);
 
     (this as Writable<this>).status = VALID;
+    this._status.set(VALID);
     this._forEachChild((control: AbstractControl) => {
       control.enable({...opts, onlySelf: true});
     });
@@ -1302,6 +1322,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
       this._cancelExistingSubscription();
       (this as Writable<this>).errors = this._runValidator();
       (this as Writable<this>).status = this._calculateStatus();
+      this._status.set(this.status);
 
       if (this.status === VALID || this.status === PENDING) {
         this._runAsyncValidator(opts.emitEvent);
@@ -1329,6 +1350,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
 
   private _setInitialStatus() {
     (this as Writable<this>).status = this._allControlsDisabled() ? DISABLED : VALID;
+    this._status.set(this.status);
   }
 
   private _runValidator(): ValidationErrors | null {
@@ -1338,6 +1360,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   private _runAsyncValidator(emitEvent?: boolean): void {
     if (this.asyncValidator) {
       (this as Writable<this>).status = PENDING;
+      this._status.set(PENDING);
       this._hasOwnPendingAsyncValidator = true;
       const obs = toObservable(this.asyncValidator(this));
       this._asyncValidationSubscription = obs.subscribe((errors: ValidationErrors | null) => {
@@ -1534,6 +1557,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   /** @internal */
   _updateControlsErrors(emitEvent: boolean, changedControl: AbstractControl): void {
     (this as Writable<this>).status = this._calculateStatus();
+    this._status.set(this.status);
 
     if (emitEvent) {
       (this.statusChanges as EventEmitter<FormControlStatus>).emit(this.status);
@@ -1594,6 +1618,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
     const newPristine = !this._anyControlsDirty();
     const changed = this.pristine !== newPristine;
     (this as Writable<this>).pristine = newPristine;
+    this._pristine.set(newPristine);
 
     if (this._parent && !opts.onlySelf) {
       this._parent._updatePristine(opts, changedControl);
@@ -1607,6 +1632,7 @@ export abstract class AbstractControl<TValue = any, TRawValue extends TValue = T
   /** @internal */
   _updateTouched(opts: {onlySelf?: boolean} = {}, changedControl: AbstractControl): void {
     (this as Writable<this>).touched = this._anyControlsTouched();
+    this._touched.set(this.touched);
     this._events.next(new TouchedChangeEvent(this.touched, changedControl));
 
     if (this._parent && !opts.onlySelf) {