Angular components as self validating formControls - javascript

I'm not sure if there's a better way to do this, I assume there should be. Basically I have a component I want to treat as a standalone form control. This control will always have some sort of special validation attached and I would like it to bubble up to the form whenever the component is used.
I've attached a plunker. Is there a way to for the form to be marked invalid if the component/formControl is invalid? I know I could add the validator to the form itself, but I would like to make things easy and more predictable for future use of this component. I'm also open to better ideas of doing this.
#Component({
selector: 'my-app',
template: `
<form [formGroup]="form">
<my-component-control formControlName="myComponent"></my-component-control>
</form>
<div>Form Value: {{form.value | json}}</div>
<div>Form Valid: {{form.valid}}</div>
`,
})
export class App {
constructor(fb: FormBuilder) {
this.form = fb.group({
myComponent: ''
});
}
}
#Component({
selector: 'my-component-control',
template: `
<div>Control Errors: {{control.errors | json}}</div>
<input [formControl]="control">
`,
providers: [
{
provide: NG_VALUE_ACCESSOR,
multi: true,
useExisting: forwardRef(() => MyComponentComponent),
}
]
})
export class MyComponentComponent implements ControlValueAccessor {
control: FormControl;
onChange: any = () => { };
onTouched: any = () => { };
constructor() {
this.control = new FormControl('', (control) => {
return control.value ? null : {shouldHaveSomething: true};
});
this.control.valueChanges.subscribe((value) => {
this.onChange(value);
this.onTouched();
});
}
writeValue (obj: any): void {
this.control.setValue(obj);
}
registerOnChange (fn: any): void {
this.onChange = fn;
}
registerOnTouched (fn: any): void {
this.onTouched = fn;
}
setDisabledState?(isDisabled: boolean): void {
throw new Error('Method not implemented.');
}
}

One solution could be using setValidators method on host AbstractControl
To do so I'm going to get reference to AbstractControl through NgControl. We can't just inject NgControl in constructor because we'll get issue with instantiating cyclic dependency.
constructor(private injector: Injector) {
...
}
ngOnInit() {
Promise.resolve().then(() => {
const hostControl = this.injector.get(NgControl, null);
if (hostControl) {
hostControl.control.setValidators(this.control.validator);
hostControl.control.updateValueAndValidity();
}
});
}
Ng-run Example

Related

Angular: Accessor not doing two-way-binding

I am trying to write an accessor component, for an input that has a label associated with it, but I am not sure if I am doing this correctly. When I attempt to do two-way-binding, the value isn't set in the input field even though it is set within the class MyComponent.
Why isn't my two-way-binding working? I would expect to see Something Special inside the <input> that is within <third-party-input>. However, the input is empty.
When using <third-party-input> on its own, two-way-binding works there, just not when I wrap my component around it.
Main Component
<ui-input [(ngModel)]="myValue"></ui-input>
export class MyComponent {
public myValue = 'Something Special';
}
Input With Label Component
<label>{{label}}</label>
<third-party-input [(ngModel)]="value"></third-party-input>
#Component({
selector: 'ui-input',
templateUrl: './input.component.html',
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => InputComponent),
multi: true
}]
})
export class InputComponent extends AccessorComponent {}
#Component({
selector: 'app-accessor',
template: ''
})
export abstract class AccessorComponent implements ControlValueAccessor {
protected _value: any;
public get value() {
return this._value;
}
public set value(val) {
this._value = val;
this.onChange(val);
this.onTouched();
}
protected onChange = (_: any) => { };
protected onTouched: any = () => { };
public registerOnChange(fn: (_: any) => void): void {
this.onChange = fn;
}
public registerOnTouched(fn: () => void): void {
this.onTouched = fn;
}
public writeValue(value: any): void {
if (value !== undefined) {
this._value = value;
}
}
}

How to unselect selected option-element in select-element using Angular 8

I have the following requirements:
I got two FormControl objects for select-elements mainSelect and subSelect that are required.
subSelect changes depending on the value from mainSelect.
When mainSelect changes to a value in which the value from subSelect isn't included subSelect needs to become invalid so the FormGroup both of the FormControl's are part of becomes invalid, too.
But if the value from subSelect is included subSelect needs to hold his actual value.
(A concrete example is described after the StackBlitz link.)
My problem solving this requirement:
If the value of mainSelect changes and the value of subSelect isn't included subSelect takes the first value of the list instead of becoming null/invalid.
So the SOLUTION would be if the selected value of 'subSelect' becomes null and no value is selected in the browser.
What I tried so far:
I tried to create a component and implement the ControlValueAccessor interface. Seems like here lies my problem. I think I don't really understand how that works.
I watched the following video on YouTube and read articles (1, 2) related to ControlValueAccessor, but still couldn't solve my problem.
This is part of my code:
Also you can find it on StackBlitz
Example
If in the browser MainSelect has the value thirdMainSelect and SubSelect has the value fifthSubSelect and MainSelect changes his value to firstMainSelect SubSelect should have no selected value.
select.component.ts
export class SomeObject {
value: string;
parameters: {[parameterName: string]: string} = {};
}
#Component({
selector: "app-select",
templateUrl: "./select.component.html",
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: SelectComponent,
multi: true
}]
})
export class SelectComponent implements ControlValueAccessor, OnChanges {
#ViewChild("select", {static: true}) select: ElementRef;
#Input() tableId: string;
#Input() filter: { [parameterName: string]: string};
returnedTable: SomeObject[];
onChange: (_: any) => void;
onTouched: () => void;
selected: string;
constructor(private tableService: TableService) { }
loadTable(): void {
this.tableService.getTable(this.tableId, this.filter)
.subscribe(table => {
this.returnedTable = table;
});
}
ngOnChanges(): void {
this.loadTable();
}
registerOnChange(fn: any): void {
this.onChange = fn;
}
registerOnTouched(fn: any): void {
this.onTouched = fn;
}
writeValue(value: string): void {
this.selected = value;
}
}
select.component.html
<select class="form-control" #select (change)="onChange($event.target.value)">
<option *ngFor="let item of returnedTable" [value]="item.value" [selected]="selected === item.value">{{item.value}}</option>
</select>
app.component.ts
#Component({
selector: "app-root",
templateUrl: "./app.component.html",
styleUrls: ["./app.component.scss"]
})
export class AppComponent implements OnInit {
form: FormGroup;
containerObject: ContainerObject;
selectedMainValue: string;
constructor(private tableService: TableService,
private formBuilder: FormBuilder) {
}
ngOnInit(): void {
this.tableService.getContainerObject()
.subscribe(containerObject => {
this.containerObject = containerObject;
this.selectedMainValue = containerObject.mainSelect;
this.initForm();
});
}
private initForm(): void {
this.form = this.formBuilder.group({
mainSelect: [this.containerObject.mainSelect, Validators.required],
subSelect: [this.containerObject.subSelect, Validators.required]
});
this.subscribeToMainSelectChanged();
this.subscribeToSubSelectChanged();
}
onSubmit(): void {
if (this.form.valid) {
this.containerObject.mainSelect = this.form.get("mainSelect").value;
this.containerObject.subSelect = this.form.get("subSelect").value;
this.tableService.saveContainerObject(this.containerObject);
}
}
private subscribeToMainSelectChanged() {
this.form.get("mainSelect").valueChanges
.subscribe(mainSelect => {
this.selectedMainValue = mainSelect;
console.log(this.form.status);
});
}
private subscribeToSubSelectChanged() {
this.form.get("subSelect").valueChanges
.subscribe(() => {
console.log(this.form.status);
});
}
}
app.component.html
<div>
<form id="wrapper" [formGroup]="form" (ngSubmit)="onSubmit()">
<div id="left" class="form-group row">
<label for="mainSelect" class="col-form-label col-sm-2">MainSelect</label>
<div class="col-sm-6">
<app-select
id="mainSelect"
formControlName="mainSelect"
[tableId]="'mainSelectTable'"
[filter]="{firstType: 'firstParameter'}"
></app-select>
</div>
</div>
<div id="right" class="form-group row">
<label for="subSelect" class="col-form-label col-sm-2">SubSelect</label>
<div class="col-sm-6">
<app-select
id="subSelect"
formControlName="subSelect"
[tableId]="'firstParameter'"
[filter]="{firstType: 'firstParameter', secondType: selectedMainValue}"></app-select>
</div>
</div>
<p></p>
<button id="button" type="submit">Submit</button>
</form>
</div>
I think that it's only use valuesChange. If you has two arrays data and subdata and a form like
form = new FormGroup({
prop1: new FormControl(),
prop2: new FormControl()
});
A simple
this.form.get("prop1").valueChanges.subscribe(res => {
this.dataService.getData(res).subscribe(data=>{
this.subdata=data;
if (!this.subdata.find(x=>x.value==this.form.get("prop2").value))
this.form.get("prop2").setValue(null);
}).unsubscribe()
});
must be enough, see stackblitz
After a while trying to solve this problem only using the SelectComponent and especially writeValue, the following code did the job:
I changed the select.component.ts as following:
export class SomeObject {
value: string;
parameters: {[parameterName: string]: string} = {};
}
#Component({
selector: "app-select",
templateUrl: "./select.component.html",
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: SelectComponent,
multi: true
}]
})
export class SelectComponent implements ControlValueAccessor, OnChanges {
#ViewChild("select", {static: true}) select: ElementRef;
#Input() tableId: string;
#Input() filter: { [parameterName: string]: string};
returnedTable: SomeObject[];
onChange: (_: any) => void;
onTouched: () => void;
selected: string;
constructor(private tableService: TableService) { }
loadTable(): void {
this.tableService.getTable(this.tableId, this.filter)
.subscribe(table => {
this.returnedTable = table;
if (!!this.select && !!this.select.nativeElement.value) {
this.writeValue(this.select.nativeElement.value);
this.onChange(this.selected);
}
});
}
ngOnChanges(): void {
this.loadTable();
}
registerOnChange(fn: any): void {
this.onChange = fn;
}
registerOnTouched(fn: any): void {
this.onTouched = fn;
}
writeValue(value: string): void {
if (!!this.returnedTable && !this.returnedTable.some(item => item.value === value)) {
this.selected = null;
} else {
this.selected = value;
}
}
}
And the select.component.html like this:
<select class="form-control" #select (change)="onChange($event.target.value)">
<option hidden *ngIf="!selected" value=""></option>
<option *ngFor="let item of returnedTable" [value]="item.value" [selected]="selected === item.value">{{item.value}}</option>
</select>
To deselect an option:— option.selected = false.
Angular library with function decompilation at its core for $scope and Nested Forms, an Angular feature that indicates that Angular team doesn't know how to effectively use HTML. HTML doesn't allow nested forms so why the hell would you try to shoehorn the language to do that? More trouble than it's worth. Of course, you can't expect much better from guys like Bradley Green, former Angular JS manager.

Angular: trying to add recaptcha. Error => No value accessor for form control with name: 'captcha'

So I followed a tutorial on how to add recaptcha to a form to prevent spam. I followed all the steps, but I still get the following error:
error inside log Error: No value accessor for form control with name: 'captcha'
at _throwError (forms.js:2139)
at setUpControl (forms.js:2008)
at FormGroupDirective.addControl (forms.js:5144)
at FormControlName._setUpControl (forms.js:5743)
at FormControlName.ngOnChanges (forms.js:5684)
at checkAndUpdateDirectiveInline (core.js:11642)
at checkAndUpdateNodeInline (core.js:13252)
I have a reactive signup form where I have the following element that's supposed to be the captcha and a formControl. BUt unfortunately I see nothing.
<div nbRecaptcha key="6LfNfHYUAAAAAFaa7dVi2au1tnfod-2eR3Rb2enM" formControlName="captcha"></div>
This is the nbRecaptcha directive:
declare const grecaptcha: any;
declare global {
interface Window {
grecaptcha: any;
reCaptchaLoad: () => void
}
}
#Directive({
selector: '[nbRecaptcha]',
providers: [ReCaptchaAsyncValidator]
})
export class RecaptchaDirective implements OnInit, ControlValueAccessor, AfterViewInit {
#Input() key: string;
#Input() config: ReCaptchaConfig = {};
#Input() lang: string;
private control: FormControl;
private onChange: ( value: string ) => void;
private onTouched: ( value: string ) => void;
private widgetId: number;
constructor(
private element: ElementRef,
private ngZone: NgZone,
private injector: Injector,
private reCaptchaAsyncValidator: ReCaptchaAsyncValidator){}
ngOnInit() {
this.registerReCaptchaCallback();
this.addScript();
}
ngAfterViewInit() {
this.control = this.injector.get(NgControl).control;
this.setValidator();
}
addScript() {
let script = document.createElement('script');
const lang = this.lang ? '&hl=' + this.lang : '';
script.src = `https://www.google.com/recaptcha/api.js?onload=reCaptchaLoad&render=explicit${lang}`;
script.async = true;
script.defer = true;
document.body.appendChild(script);
}
// We need to notify the formControl that it’s valid if we get the token
// from the onSuccess function or that it’s invalid if the onExpired function is called.
onExpired() {
this.ngZone.run(() => {
this.onChange(null);
this.onTouched(null);
});
}
onSuccess( token: string ) {
this.ngZone.run(() => {
this.verifyToken(token);
this.onChange(token);
this.onTouched(token);
});
}
// these are the three methods that controlValueAccessor requires
writeValue( obj: any ): void {
}
registerOnChange( fn: any ): void {
this.onChange = fn;
}
registerOnTouched( fn: any ): void {
this.onTouched = fn;
}
private setValidator() {
this.control.setValidators(Validators.required);
this.control.updateValueAndValidity();
}
registerReCaptchaCallback() {
window.reCaptchaLoad = () => {
const config = {
...this.config,
'sitekey': this.key,
'callback': this.onSuccess.bind(this),
'expired-callback': this.onExpired.bind(this)
};
this.widgetId = this.render(this.element.nativeElement, config);
};
}
private render( element: HTMLElement, config ): number {
return grecaptcha.render(element, config);
}
verifyToken( token : string ) {
this.control.setAsyncValidators(this.reCaptchaAsyncValidator.validateToken(token))
this.control.updateValueAndValidity();
}
}
And the signup component form:
this.mySignupForm = new FormGroup({
captcha: new FormControl()
});
Can Anyone see what I did wrong?
The error No value accessor for form control with name: 'captcha'. This can be resolved by adding the directive/control to list of all available NG_VALUE_ACCESSORs using forwardRef. You are effectively extending the multi-provider for NG_VALUE_ACCESSOR so that this directive can access ControlValueAccessor.
#Directive({
selector: '[nbRecaptcha]',
providers: [
{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => RecaptchaDirective),
multi: true
},
ReCaptchaAsyncValidator
]
})
Here is a mostly working example with that specific error being resolved. I had to remove some of the custom classes/configurations you had in your example as I wasn't aware of their exact implementations.
I could not find official documentation for creating custom controls, but there are a few solid articles out there discussing creating custom controls that reference this necessary registration.
Hopefully that helps!
Sometimes we get this kind of error when import it in app.module instead of the own module where we need to use . for example
///app.module.ts
import { RecaptchaModule, RecaptchaFormsModule } from "ng-recaptcha";
imports: [
BrowserModule,
RecaptchaModule,
RecaptchaFormsModule
]
move it to --->
///x.module.ts
import { RecaptchaModule, RecaptchaFormsModule } from "ng-recaptcha";
#NgModule({
imports: [
FormsModule,
RecaptchaModule,
RecaptchaFormsModule,
],
providers:[
{
provide: RECAPTCHA_SETTINGS,
useValue: { siteKey: environment.recaptcha.siteKey } as RecaptchaSettings,
},
]

Why ngModel don't trigger changedetection in writevalue method?

I wrote a very simple custom form control and I didn't change it's changeDetectionStrategy.
#Component({
selector: 'counter',
template: `
<button (click)="increase($event)">+</button>
{{counter}}
<button (click)="decrease($event)">-</button>
`,
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => CounterComponent),
multi: true
}]
})
export class CounterComponent implements OnInit, ControlValueAccessor {
private counter: number = 0;
private onChange: (_: any) => void;
private onTouched: () => void;
constructor(private _cdr: ChangeDetectorRef) { }
ngOnInit() { }
writeValue(value) {
console.log(`Write value`, value);
this.counter = value;
// this._cdr.markForCheck(); // it works
// Use onChange works too
// if (this.onChange) {
// this.onChange(value);
// }
}
registerOnChange(fn: (_: any) => void): void { this.onChange = fn; }
registerOnTouched(fn: () => void): void { this.onTouched = fn; }
increase() {
this.counter++;
this.onChange(this.counter);
}
decrease() {
this.counter--;
this.onChange(this.counter);
}
}
Then I use it in a component named ngmodel-demo with onPush changeDetectionStrategy.
#Component({
selector: 'ngmodel-demo',
template: `
<h3>NgModel Demo</h3>
<p>Count: {{count}}</p>
<counter [(ngModel)]="count"></counter>
`,
changeDetection: ChangeDetectionStrategy.OnPush
})
export class NgmodelDemoComponent {
#Input() name: string;
public count = 1;
constructor(private _cdRef: ChangeDetectorRef) {}
}
When I ran the app, I found that the counter component have got the value 1, but its view didn't update.
Then I set a timer to update the ngModel and mark for check.
ngOnInit() {
setInterval(() => {
this.count = ++this.count;
this._cdRef.markForCheck();
}, 3000);
}
The result is that each time the value that counter component's view shows is the value of the last ngModel's.
Manually calling markForCheck in writeValue method works. But I did not use the onPush strategy, I do not understand why to manually call?
There is also a puzzle that is why calling onChange in writeValue also works.
Online demo link on stackblitz: https://stackblitz.com/edit/angular-cfc-writevalue
It is a bug in Angular. I opened an issue about it. You can subscribe if interested.

Why Pipe doesn't work correctly in Angular2?

The task is simple, it is necessary that the input was entered only numbers below a certain number. I did so:
export class MaxNumber implements PipeTransform{
transform(value, [maxNumber]) {
value = value.replace(/[^\d]+/g,'');
value = value > maxNumber?maxNumber:value;
return value;
}
}
and then in the template called something like:
<input type="text" [ngModel]="obj.count | maxNumber:1000" (ngModelChange)="obj.count=$event" />
But it works very strange click.
I probably misunderstand something. I would be grateful if someone will explain that behavior.
I think that you need rather a custom value accessor. This way you will be able to check the value before setting it in the ngModel. This way you obj.count won't be upper than 1000.
Here is a sample implementation:
const CUSTOM_VALUE_ACCESSOR = new Provider(
NG_VALUE_ACCESSOR, {useExisting: forwardRef(() => MaxNumberAccessor), multi: true});
#Directive({
selector: 'input',
host: {'(input)': 'customOnChange($event.target.value)'},
providers: [ CUSTOM_VALUE_ACCESSOR ]
})
export class MaxNumberAccessor implements ControlValueAccessor {
onChange = (_) => {};
onTouched = () => {};
constructor(private _renderer: Renderer, private _elementRef: ElementRef) {}
writeValue(value: any): void {
var normalizedValue = (value == null) ? '' : value;
this._renderer.setElementProperty(this._elementRef.nativeElement, 'value', normalizedValue);
}
customOnChange(val) {
var maxNumber = 1000;
val = val.replace(/[^\d]+/g,'');
val = val > maxNumber?maxNumber:val;
this.onChange(val);
}
registerOnChange(fn: (_: any) => void): void { this.onChange = fn; }
registerOnTouched(fn: () => void): void { this.onTouched = fn; }
}
There is nothing to do in your component to use it than setting this directive into its directives attribute:
#Component({
selector: 'my-app',
template: `
<div>
<h2>Hello {{name}}</h2>
Number: <input type="text" [(ngModel)]="obj.count" />
<p>Actual model value: {{obj.count}}</p>
</div>
`,
directives: [MaxNumberAccessor]
})
export class App {
(...)
}
Corresponding plunkr: https://plnkr.co/edit/7e87xZoEHnnm82OYP84o?p=preview.

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