fix(forms): allow FormRoot to be used without submission options (#67727)

The `[formRoot]` directive will no longer call `submit()` if the bound
form doesn't define its own submission options. This allows the
directive to be used solely for the default behavior it provides:
setting `novalidate` on the `<form>` and calling `preventDefault()` on
the `submit` event.

Fix #67367

PR Close #67727

packages/forms/signals/src/directive/form_root.ts

@@ -6,10 +6,11 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-import {Directive, input} from '@angular/core';
+import {Directive, input, untracked} from '@angular/core';
 
 import {submit} from '../api/structure';
-import {FieldTree} from '../api/types';
+import {FieldState, FieldTree} from '../api/types';
+import {FieldNode} from '../field/node';
 
 /**
  * A directive that binds a `FieldTree` to a `<form>` element.
@@ -17,7 +18,7 @@ import {FieldTree} from '../api/types';
  * It automatically:
  * 1. Sets `novalidate` on the form element to disable browser validation.
  * 2. Listens for the `submit` event, prevents the default behavior, and calls `submit()` on the
- * `FieldTree`.
+ * `FieldTree` if it defines its own submission options.
  *
  * @usageNotes
  *
@@ -42,6 +43,14 @@ export class FormRoot<T> {
 
   protected onSubmit(event: Event): void {
     event.preventDefault();
-    submit(this.fieldTree());
+
+    untracked(() => {
+      const fieldTree = this.fieldTree();
+      const node = fieldTree() as FieldState<unknown> as FieldNode;
+
+      if (node.structure.fieldManager.submitOptions) {
+        submit(fieldTree);
+      }
+    });
   }
 }

packages/forms/signals/test/node/form_root.spec.ts

@@ -44,7 +44,7 @@ describe('FormRoot', () => {
     expect(formElement.hasAttribute('novalidate')).toBeTrue();
   });
 
-  it('should call submit on the field tree when form is submitted', async () => {
+  it('should call submit if the field tree defines submit options', async () => {
     const fixture = act(() => TestBed.createComponent(TestCmp));
     const component = fixture.componentInstance;
     const formElement = fixture.nativeElement.querySelector('form') as HTMLFormElement;
@@ -53,9 +53,34 @@ describe('FormRoot', () => {
     act(() => formElement.dispatchEvent(event));
 
     expect(event.defaultPrevented).toBe(true);
+    expect(component.f().touched()).toBeTrue();
     expect(component.submitted).toBeTrue();
   });
 
+  it('should not call submit if the field tree does not define submit options', async () => {
+    @Component({
+      template: `
+        <form [formRoot]="f">
+          <button type="submit">Submit</button>
+        </form>
+      `,
+      imports: [FormRoot],
+    })
+    class TestCmpNoSubmit {
+      readonly f = form(signal({}));
+    }
+
+    const fixture = act(() => TestBed.createComponent(TestCmpNoSubmit));
+    const component = fixture.componentInstance;
+    const formElement = fixture.nativeElement.querySelector('form') as HTMLFormElement;
+
+    const event = new Event('submit', {cancelable: true});
+    act(() => formElement.dispatchEvent(event));
+
+    expect(event.defaultPrevented).toBe(true);
+    expect(component.f().touched()).withContext('submit would mark this as touched').toBeFalse();
+  });
+
   it('works when FormsModule is imported', () => {
     @Component({
       template: `