fix(forms): match getError and hasError to get method signature (#20211)

Internally getError and hasError call the AbstractControl#get method which takes  `path: Array<string | number> | string` as input, since there are different ways to traverse the AbstractControl tree.
This change matches the method signitures of all methods that use this.

PR Close #20211

packages/forms/src/directives/abstract_control_directive.ts

@@ -177,7 +177,7 @@ export abstract class AbstractControlDirective {
    *
    * If the control is not present, false is returned.
    */
-  hasError(errorCode: string, path?: string[]): boolean {
+  hasError(errorCode: string, path?: Array<string|number>|string): boolean {
     return this.control ? this.control.hasError(errorCode, path) : false;
   }
 
@@ -208,7 +208,7 @@ export abstract class AbstractControlDirective {
    * @returns error data for that particular error. If the control or error is not present,
    * null is returned.
    */
-  getError(errorCode: string, path?: string[]): any {
+  getError(errorCode: string, path?: Array<string|number>|string): any {
     return this.control ? this.control.getError(errorCode, path) : null;
   }
 }

packages/forms/src/model.ts

@@ -671,7 +671,7 @@ export abstract class AbstractControl {
    * @returns error data for that particular error. If the control or error is not present,
    * null is returned.
    */
-  getError(errorCode: string, path?: string[]): any {
+  getError(errorCode: string, path?: Array<string|number>|string): any {
     const control = path ? this.get(path) : this;
     return control && control.errors ? control.errors[errorCode] : null;
   }
@@ -706,7 +706,9 @@ export abstract class AbstractControl {
    *
    * If the control is not present, false is returned.
    */
-  hasError(errorCode: string, path?: string[]): boolean { return !!this.getError(errorCode, path); }
+  hasError(errorCode: string, path?: Array<string|number>|string): boolean {
+    return !!this.getError(errorCode, path);
+  }
 
   /**
    * Retrieves the top-level ancestor of this control.

packages/forms/test/form_group_spec.ts

@@ -684,6 +684,70 @@ import {of } from 'rxjs';
         expect(g.getError('required', ['one'])).toEqual(null);
         expect(g.getError('required', ['invalid'])).toEqual(null);
       });
+
+      it('should be able to traverse group with single string', () => {
+        const c = new FormControl('', Validators.required);
+        const g = new FormGroup({'one': c});
+        expect(c.getError('required')).toEqual(true);
+        expect(g.getError('required', 'one')).toEqual(true);
+      });
+
+      it('should be able to traverse group with string delimited by dots', () => {
+        const c = new FormControl('', Validators.required);
+        const g2 = new FormGroup({'two': c});
+        const g1 = new FormGroup({'one': g2});
+        expect(c.getError('required')).toEqual(true);
+        expect(g1.getError('required', 'one.two')).toEqual(true);
+      });
+
+      it('should traverse group with form array using string and numbers', () => {
+        const c = new FormControl('', Validators.required);
+        const g2 = new FormGroup({'two': c});
+        const a = new FormArray([g2]);
+        const g1 = new FormGroup({'one': a});
+        expect(c.getError('required')).toEqual(true);
+        expect(g1.getError('required', ['one', 0, 'two'])).toEqual(true);
+      });
+    });
+
+    describe('hasError', () => {
+      it('should return true when it is present', () => {
+        const c = new FormControl('', Validators.required);
+        const g = new FormGroup({'one': c});
+        expect(c.hasError('required')).toEqual(true);
+        expect(g.hasError('required', ['one'])).toEqual(true);
+      });
+
+      it('should return false otherwise', () => {
+        const c = new FormControl('not empty', Validators.required);
+        const g = new FormGroup({'one': c});
+        expect(c.hasError('invalid')).toEqual(false);
+        expect(g.hasError('required', ['one'])).toEqual(false);
+        expect(g.hasError('required', ['invalid'])).toEqual(false);
+      });
+
+      it('should be able to traverse group with single string', () => {
+        const c = new FormControl('', Validators.required);
+        const g = new FormGroup({'one': c});
+        expect(c.hasError('required')).toEqual(true);
+        expect(g.hasError('required', 'one')).toEqual(true);
+      });
+
+      it('should be able to traverse group with string delimited by dots', () => {
+        const c = new FormControl('', Validators.required);
+        const g2 = new FormGroup({'two': c});
+        const g1 = new FormGroup({'one': g2});
+        expect(c.hasError('required')).toEqual(true);
+        expect(g1.hasError('required', 'one.two')).toEqual(true);
+      });
+      it('should traverse group with form array using string and numbers', () => {
+        const c = new FormControl('', Validators.required);
+        const g2 = new FormGroup({'two': c});
+        const a = new FormArray([g2]);
+        const g1 = new FormGroup({'one': a});
+        expect(c.getError('required')).toEqual(true);
+        expect(g1.getError('required', ['one', 0, 'two'])).toEqual(true);
+      });
     });
 
     describe('validator', () => {

tools/public_api_guard/forms/forms.d.ts

@@ -30,8 +30,8 @@ export declare abstract class AbstractControl {
         emitEvent?: boolean;
     }): void;
     get(path: Array<string | number> | string): AbstractControl | null;
-    getError(errorCode: string, path?: string[]): any;
+    getError(errorCode: string, path?: Array<string | number> | string): any;
-    hasError(errorCode: string, path?: string[]): boolean;
+    hasError(errorCode: string, path?: Array<string | number> | string): boolean;
     markAsDirty(opts?: {
         onlySelf?: boolean;
     }): void;
@@ -80,8 +80,8 @@ export declare abstract class AbstractControlDirective {
     readonly valid: boolean | null;
     readonly value: any;
     readonly valueChanges: Observable<any> | null;
-    getError(errorCode: string, path?: string[]): any;
+    getError(errorCode: string, path?: Array<string | number> | string): any;
-    hasError(errorCode: string, path?: string[]): boolean;
+    hasError(errorCode: string, path?: Array<string | number> | string): boolean;
     reset(value?: any): void;
 }