feat(lib): formGroup validator oneOf

This closes #91

README.md

@@ -521,6 +521,7 @@ export class CrewMemberComponent extends NgxSubFormComponent<CrewMember> {
 
 - `emitNullOnDestroy`: By default is set to `true` for `NgxSubFormComponent`, `NgxSubFormRemapComponent` and to `false` for `NgxRootFormComponent` and `NgxAutomaticRootFormComponent`. When set to `true`, if the sub form component is being destroyed, it will emit one last value: `null`. It might be useful to set it to `false` for e.g. when you've got a form accross multiple tabs and once a part of the form is filled you want to destroy it
 - `emitInitialValueOnInit`: By default is set to `true` for `NgxSubFormComponent`, `NgxSubFormRemapComponent` and to `false` for `NgxRootFormComponent` and `NgxAutomaticRootFormComponent`. When set to `true`, the sub form component will emit the first value straight away (default one unless the component above as a value already set on the `formControl`)
+- `ngxSubFormValidators`: An object containing validator methods. Currently, only`oneOf`is available. It lets you specify on a`formGroup`using`getFormGroupControlOptions` that amongst some properties, exactly one should be defined (nothing more, nothing less)
 
 **Hooks**
 
@@ -553,7 +554,7 @@ class PasswordSubFormComponent extends NgxSubFormComponent<PasswordForm> {
     };
   }
 
-  public getFormGroupControlOptions(): FormGroupOptions<PasswordForm> {
+  protected getFormGroupControlOptions(): FormGroupOptions<PasswordForm> {
     return {
       validators: [
         formGroup => {

projects/ngx-sub-form/src/lib/ngx-sub-form-utils.ts

@@ -75,6 +75,18 @@ export class MissingFormControlsError<T extends string> extends Error {
   }
 }
 
+export class OneOfValidatorRequiresMoreThanOneFieldError extends Error {
+  constructor() {
+    super(`"oneOf" validator requires to have at least 2 keys`);
+  }
+}
+
+export class OneOfValidatorUnknownFieldError extends Error {
+  constructor(field: string) {
+    super(`"oneOf" validator requires to keys from the FormInterface and "${field}" is not`);
+  }
+}
+
 export const NGX_SUB_FORM_HANDLE_VALUE_CHANGES_RATE_STRATEGIES = {
   debounce: <T, U>(time: number): ReturnType<NgxSubFormComponent<T, U>['handleEmissionRate']> => obs =>
     obs.pipe(debounce(() => timer(time))),
@@ -85,6 +97,7 @@ export const NGX_SUB_FORM_HANDLE_VALUE_CHANGES_RATE_STRATEGIES = {
  * If the component already has a `ngOnDestroy` method defined, it will call this first.
  * Note that the component *must* implement OnDestroy for this to work (the typings will enforce this anyway)
  */
+/** @internal */
 export function takeUntilDestroyed<T>(component: OnDestroy): (source: Observable<T>) => Observable<T> {
   return (source: Observable<T>): Observable<T> => {
     const onDestroy = new Subject();

projects/ngx-sub-form/src/lib/ngx-sub-form.component.spec.ts

@@ -1,6 +1,6 @@
 /// <reference types="jasmine" />
 
-import { FormControl, Validators, FormArray } from '@angular/forms';
+import { FormControl, Validators, FormArray, ValidatorFn } from '@angular/forms';
 import {
   FormGroupOptions,
   NgxSubFormComponent,
@@ -11,6 +11,8 @@ import {
   ArrayPropertyKey,
   ArrayPropertyValue,
   NgxFormWithArrayControls,
+  OneOfValidatorRequiresMoreThanOneFieldError,
+  OneOfValidatorUnknownFieldError,
 } from '../public_api';
 import { Observable } from 'rxjs';
 
@@ -442,10 +444,37 @@ describe(`NgxSubFormComponent`, () => {
       }
     }
 
+    interface DroidForm {
+      assassinDroid: { type: 'Assassin' };
+      medicalDroid: { type: 'Medical' };
+    }
+
+    class DroidFormComponent extends NgxSubFormComponent<DroidForm> {
+      protected getFormControls() {
+        return {
+          assassinDroid: new FormControl(null),
+          medicalDroid: new FormControl(null),
+        };
+      }
+
+      public getFormGroupControlOptions(): FormGroupOptions<DroidForm> {
+        return {
+          validators: [this.ngxSubFormValidators.oneOf([['assassinDroid', 'medicalDroid']])],
+        };
+      }
+
+      // testing utility
+      public setValidatorOneOf(keysArray: (keyof DroidForm)[][]): void {
+        this.formGroup.setValidators([(this.ngxSubFormValidators.oneOf(keysArray) as unknown) as ValidatorFn]);
+      }
+    }
+
     let validatedSubComponent: ValidatedSubComponent;
+    let droidFormComponent: DroidFormComponent;
 
     beforeEach((done: () => void) => {
       validatedSubComponent = new ValidatedSubComponent();
+      droidFormComponent = new DroidFormComponent();
 
       // we have to call `updateValueAndValidity` within the constructor in an async way
       // and here we need to wait for it to run
@@ -473,6 +502,97 @@ describe(`NgxSubFormComponent`, () => {
         }, 0);
       }, 0);
     });
+
+    describe('ngxSubFormValidators', () => {
+      it('oneOf should throw an error if no value or only one in the array', () => {
+        expect(() => droidFormComponent.setValidatorOneOf(undefined as any)).toThrow(
+          new OneOfValidatorRequiresMoreThanOneFieldError(),
+        );
+
+        expect(() => droidFormComponent.setValidatorOneOf([])).toThrow(
+          new OneOfValidatorRequiresMoreThanOneFieldError(),
+        );
+
+        expect(() => droidFormComponent.setValidatorOneOf([[]])).toThrow(
+          new OneOfValidatorRequiresMoreThanOneFieldError(),
+        );
+
+        expect(() => droidFormComponent.setValidatorOneOf([['assassinDroid']])).toThrow(
+          new OneOfValidatorRequiresMoreThanOneFieldError(),
+        );
+
+        expect(() => droidFormComponent.setValidatorOneOf([['assassinDroid', 'medicalDroid']])).not.toThrow();
+      });
+
+      it('oneOf should throw an error if there is an unknown key', () => {
+        droidFormComponent.setValidatorOneOf([['unknown 1' as any, 'unknown 2' as any]]);
+        expect(() => droidFormComponent.formGroup.updateValueAndValidity()).toThrow(
+          new OneOfValidatorUnknownFieldError('unknown 1'),
+        );
+
+        droidFormComponent.setValidatorOneOf([['assassinDroid', 'unknown 2' as any]]);
+        expect(() => droidFormComponent.formGroup.updateValueAndValidity()).toThrow(
+          new OneOfValidatorUnknownFieldError('unknown 2'),
+        );
+      });
+
+      it('oneOf should return an object (representing the error) if all the values are null', (done: () => void) => {
+        const spyOnChange = jasmine.createSpy();
+        droidFormComponent.registerOnChange(spyOnChange);
+
+        droidFormComponent.formGroup.patchValue({ assassinDroid: null, medicalDroid: null });
+
+        setTimeout(() => {
+          expect(droidFormComponent.validate()).toEqual({ formGroup: { oneOf: [['assassinDroid', 'medicalDroid']] } });
+          expect(droidFormComponent.formGroupErrors).toEqual({
+            formGroup: { oneOf: [['assassinDroid', 'medicalDroid']] },
+          });
+
+          droidFormComponent.formGroup.patchValue({
+            assassinDroid: { type: 'Assassin' },
+            medicalDroid: null,
+          });
+          setTimeout(() => {
+            expect(droidFormComponent.validate()).toEqual(null);
+            expect(droidFormComponent.formGroupErrors).toEqual(null);
+            done();
+          }, 0);
+        }, 0);
+      });
+
+      it('oneOf should return an object (error) if more than one value are not [null or undefined]', (done: () => void) => {
+        const spyOnChange = jasmine.createSpy();
+        droidFormComponent.registerOnChange(spyOnChange);
+
+        droidFormComponent.formGroup.patchValue({ assassinDroid: null, medicalDroid: null });
+
+        setTimeout(() => {
+          expect(droidFormComponent.validate()).toEqual({ formGroup: { oneOf: [['assassinDroid', 'medicalDroid']] } });
+
+          droidFormComponent.formGroup.patchValue({
+            assassinDroid: { type: 'Assassin' },
+            medicalDroid: { type: 'Medical' },
+          });
+
+          setTimeout(() => {
+            expect(droidFormComponent.validate()).toEqual({
+              formGroup: { oneOf: [['assassinDroid', 'medicalDroid']] },
+            });
+
+            droidFormComponent.formGroup.patchValue({
+              assassinDroid: null,
+              medicalDroid: { type: 'Medical' },
+            });
+
+            setTimeout(() => {
+              expect(droidFormComponent.validate()).toEqual(null);
+
+              done();
+            }, 0);
+          }, 0);
+        }, 0);
+      });
+    });
   });
 });
 

projects/ngx-sub-form/src/lib/ngx-sub-form.component.ts

@@ -21,8 +21,16 @@ import {
   isNullOrUndefined,
   ControlsType,
   ArrayPropertyKey,
+  OneOfValidatorRequiresMoreThanOneFieldError,
+  OneOfValidatorUnknownFieldError,
 } from './ngx-sub-form-utils';
-import { FormGroupOptions, NgxFormWithArrayControls, OnFormUpdate, TypedFormGroup } from './ngx-sub-form.types';
+import {
+  FormGroupOptions,
+  NgxFormWithArrayControls,
+  OnFormUpdate,
+  TypedFormGroup,
+  TypedValidatorFn,
+} from './ngx-sub-form.types';
 
 type MapControlFunction<FormInterface, MapValue> = (ctrl: AbstractControl, key: keyof FormInterface) => MapValue;
 type FilterControlFunction<FormInterface> = (ctrl: AbstractControl, key: keyof FormInterface) => boolean;
@@ -66,6 +74,63 @@ export abstract class NgxSubFormComponent<ControlInterface, FormInterface = Cont
 
   private controlKeys: (keyof FormInterface)[] = [];
 
+  // instead of having the validators defined in the utils file
+  // we define them here to have access to the form types
+
+  // `ngxSubFormValidators` should be used at a group level validation
+  // with the `getFormGroupControlOptions` hook
+  protected ngxSubFormValidators = {
+    oneOf(keysArray: (keyof FormInterface)[][]): TypedValidatorFn<FormInterface> {
+      if (!keysArray || !keysArray.length || keysArray.some(keys => !keys || keys.length < 2)) {
+        throw new OneOfValidatorRequiresMoreThanOneFieldError();
+      }
+
+      return (formGroup: TypedFormGroup<FormInterface>) => {
+        const oneOfErrors: (keyof FormInterface)[][] = keysArray.reduce(
+          (acc, keys) => {
+            if (!keys.length) {
+              return acc;
+            }
+
+            let nbNotNull = 0;
+            let cpt = 0;
+
+            while (cpt < keys.length && nbNotNull < 2) {
+              const key: keyof FormInterface = keys[cpt];
+
+              const control: AbstractControl | null = formGroup.get(key as string);
+
+              if (!control) {
+                throw new OneOfValidatorUnknownFieldError(key as string);
+              }
+
+              if (!isNullOrUndefined(control.value)) {
+                nbNotNull++;
+              }
+
+              cpt++;
+            }
+
+            if (nbNotNull !== 1) {
+              acc.push(keys);
+            }
+
+            return acc;
+          },
+          [] as (keyof FormInterface)[][],
+        );
+
+        if (oneOfErrors.length === 0) {
+          return null;
+        }
+
+        return {
+          oneOf: oneOfErrors,
+        };
+      };
+    },
+  };
+
   // when developing the lib it's a good idea to set the formGroup type
   // to current + `| undefined` to catch a bunch of possible issues
   // see @note form-group-undefined

src/app/app.spec.e2e.ts

@@ -81,6 +81,9 @@ context(`EJawa demo`, () => {
     DOM.createNewButton.click();
 
     DOM.form.errors.obj.should('eql', {
+      formGroup: {
+        oneOf: [['vehicleProduct', 'droidProduct']],
+      },
       listingType: {
         required: true,
       },
@@ -98,7 +101,13 @@ context(`EJawa demo`, () => {
     DOM.form.elements.selectListingTypeByType(ListingType.VEHICLE);
 
     DOM.form.errors.obj.should('eql', {
+      formGroup: {
+        oneOf: [['vehicleProduct', 'droidProduct']],
+      },
       vehicleProduct: {
+        formGroup: {
+          oneOf: [['speeder', 'spaceship']],
+        },
         vehicleType: {
           required: true,
         },
@@ -180,7 +189,13 @@ context(`EJawa demo`, () => {
     DOM.form.elements.selectListingTypeByType(ListingType.DROID);
 
     DOM.form.errors.obj.should('eql', {
+      formGroup: {
+        oneOf: [['vehicleProduct', 'droidProduct']],
+      },
       droidProduct: {
+        formGroup: {
+          oneOf: [['assassinDroid', 'astromechDroid', 'protocolDroid', 'medicalDroid']],
+        },
         droidType: {
           required: true,
         },

src/app/main/listing/listing-form/droid-listing/droid-product.component.ts

@@ -1,6 +1,6 @@
 import { Component } from '@angular/core';
 import { FormControl, Validators } from '@angular/forms';
-import { Controls, NgxSubFormRemapComponent, subformComponentProviders } from 'ngx-sub-form';
+import { Controls, NgxSubFormRemapComponent, subformComponentProviders, FormGroupOptions } from 'ngx-sub-form';
 import {
   AssassinDroid,
   AstromechDroid,
@@ -64,4 +64,12 @@ export class DroidProductComponent extends NgxSubFormRemapComponent<OneDroid, On
         throw new UnreachableCase(formValue.droidType);
     }
   }
+
+  protected getFormGroupControlOptions(): FormGroupOptions<OneDroidForm> {
+    return {
+      validators: [
+        this.ngxSubFormValidators.oneOf([['assassinDroid', 'astromechDroid', 'protocolDroid', 'medicalDroid']]),
+      ],
+    };
+  }
 }

src/app/main/listing/listing-form/listing-form.component.ts

@@ -7,6 +7,7 @@ import {
   // NGX_SUB_FORM_HANDLE_VALUE_CHANGES_RATE_STRATEGIES,
   DataInput,
   NgxRootFormComponent,
+  FormGroupOptions,
 } from 'ngx-sub-form';
 import { tap } from 'rxjs/operators';
 import { ListingType, OneListing } from 'src/app/interfaces/listing.interface';
@@ -89,4 +90,10 @@ export class ListingFormComponent extends NgxRootFormComponent<OneListing, OneLi
       ...commonValues,
     };
   }
+
+  protected getFormGroupControlOptions(): FormGroupOptions<OneListingForm> {
+    return {
+      validators: [this.ngxSubFormValidators.oneOf([['vehicleProduct', 'droidProduct']])],
+    };
+  }
 }

src/app/main/listing/listing-form/vehicle-listing/vehicle-product.component.ts

@@ -1,6 +1,6 @@
 import { Component } from '@angular/core';
 import { FormControl, Validators } from '@angular/forms';
-import { Controls, NgxSubFormRemapComponent, subformComponentProviders } from 'ngx-sub-form';
+import { Controls, NgxSubFormRemapComponent, subformComponentProviders, FormGroupOptions } from 'ngx-sub-form';
 import { OneVehicle, Spaceship, Speeder, VehicleType } from 'src/app/interfaces/vehicle.interface';
 import { UnreachableCase } from 'src/app/shared/utils';
 
@@ -47,4 +47,10 @@ export class VehicleProductComponent extends NgxSubFormRemapComponent<OneVehicle
         throw new UnreachableCase(formValue.vehicleType);
     }
   }
+
+  protected getFormGroupControlOptions(): FormGroupOptions<OneVehicleForm> {
+    return {
+      validators: [this.ngxSubFormValidators.oneOf([['speeder', 'spaceship']])],
+    };
+  }
 }

src/readme/password-sub-form.component.ts

@@ -21,7 +21,7 @@ class PasswordSubFormComponent extends NgxSubFormComponent<PasswordForm> {
     };
   }
 
-  public getFormGroupControlOptions(): FormGroupOptions<PasswordForm> {
+  protected getFormGroupControlOptions(): FormGroupOptions<PasswordForm> {
     return {
       validators: [
         formGroup => {