refactor(forms): Log a warning when FormGroup keys include a dot. (#50642)

Due to the dotted synthax to resolve controls, keys in FormGroups cannot include dots.

fixes #50608

PR Close #50642

packages/forms/src/model/form_group.ts

@@ -177,6 +177,7 @@ export class FormGroup<TControl extends {[K in keyof TControl]: AbstractControl<
       controls: TControl, validatorOrOpts?: ValidatorFn|ValidatorFn[]|AbstractControlOptions|null,
       asyncValidator?: AsyncValidatorFn|AsyncValidatorFn[]|null) {
     super(pickValidators(validatorOrOpts), pickAsyncValidators(asyncValidator, validatorOrOpts));
+    (typeof ngDevMode === 'undefined' || ngDevMode) && validateFormGroupControls(controls);
     this.controls = controls;
     this._initObservables();
     this._setUpdateStrategy(validatorOrOpts);
@@ -588,6 +589,21 @@ export class FormGroup<TControl extends {[K in keyof TControl]: AbstractControl<
   }
 }
 
+/**
+ * Will validate that none of the controls has a key with a dot
+ * Throws other wise
+ */
+function validateFormGroupControls<TControl>(
+    controls: {[K in keyof TControl]: AbstractControl<any, any>;}) {
+  const invalidKeys = Object.keys(controls).filter(key => key.includes('.'));
+  if (invalidKeys.length > 0) {
+    // TODO: make this an error once there are no more uses in G3
+    console.warn(`FormGroup keys cannot include \`.\`, please replace the keys for: ${
+        invalidKeys.join(',')}.`);
+  }
+}
+
+
 interface UntypedFormGroupCtor {
   new(controls: {[key: string]: AbstractControl},
       validatorOrOpts?: ValidatorFn|ValidatorFn[]|AbstractControlOptions|null,

packages/forms/test/form_group_spec.ts

@@ -223,7 +223,6 @@ describe('FormGroup', () => {
     });
   });
 
-
   describe('touched', () => {
     let c: FormControl, g: FormGroup;
 
@@ -2411,5 +2410,15 @@ describe('FormGroup', () => {
       }
     });
   });
+
+  it('should throw with invalid keys', () => {
+    const consoleWarnSpy = spyOn(console, 'warn');
+    new FormGroup({
+      foo: new FormControl('foo'),
+      bar: new FormControl('foo', [Validators.required]),
+      'baz.not.ok': new FormControl('baz')
+    });
+    expect(consoleWarnSpy).toHaveBeenCalledTimes(1);
+  });
 });
 })();