fix(form): set select value after option renders (#63340)

packages/forms/signals/src/controls/control.ts

@@ -7,6 +7,7 @@
  */
 
 import {
+  afterNextRender,
   computed,
   DestroyRef,
   Directive,
@@ -177,9 +178,11 @@ export class Control<T> {
     input: HTMLInputElement | HTMLTextAreaElement | HTMLSelectElement,
   ): void {
     const inputType =
-      input instanceof HTMLTextAreaElement || input instanceof HTMLSelectElement
+      input instanceof HTMLTextAreaElement
         ? 'text'
-        : input.type;
+        : input instanceof HTMLSelectElement
+          ? 'select'
+          : input.type;
 
     input.addEventListener('input', () => {
       switch (inputType) {
@@ -227,6 +230,15 @@ export class Control<T> {
           },
         );
         break;
+      case 'select':
+        this.maybeSynchronize(
+          () => this.state().value(),
+          (value) => {
+            // A select will not take a value unil the value's option has rendered.
+            afterNextRender(() => (input.value = value as string), {injector: this.injector});
+          },
+        );
+        break;
       default:
         this.maybeSynchronize(
           () => this.state().value(),

packages/forms/signals/test/web/control_directive.spec.ts

@@ -22,6 +22,7 @@ import {
   Control,
   disabled,
   form,
+  hidden,
   max,
   MAX,
   maxLength,
@@ -196,6 +197,35 @@ describe('control directive', () => {
     expect(cmp.f().value()).toBe('two');
   });
 
+  it('should assign correct value when unhiding select', () => {
+    @Component({
+      imports: [Control],
+      template: `
+        @if (!f().hidden()) {
+          <select #select [control]="f">
+            @for(opt of options; track opt) {
+              <option [value]="opt">{{opt}}</option>
+            }
+          </select>
+        }
+      `,
+    })
+    class TestCmp {
+      f = form(signal(''), (p) => hidden(p, ({value}) => value() === ''));
+      select = viewChild<ElementRef<HTMLSelectElement>>('select');
+      options = ['one', 'two', 'three'];
+    }
+
+    const fix = act(() => TestBed.createComponent(TestCmp));
+    const cmp = fix.componentInstance as TestCmp;
+
+    expect(fix.componentInstance.select()).toBeUndefined();
+
+    act(() => cmp.f().value.set('two'));
+    expect(fix.componentInstance.select()).not.toBeUndefined();
+    expect(fix.componentInstance.select()!.nativeElement.value).toEqual('two');
+  });
+
   it('synchronizes with a custom value control', () => {
     @Component({
       selector: 'my-input',