Angular: Accessor not doing two-way-binding - javascript

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;
}
}
}

Related

Angular components as self validating formControls

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

Angular custom form input with error message

I'd like to create a custom form input that is just a wrapper around the normal input and that displays an error message in case the formControl isn't valid.
So I made a component implementing ControlValueAccessor but now that I want to display the error message I realize I have no hold of the FormControl, thus I need to pass it as #Input(). The problem is... Why implement the ControlValueAccessor in the first place if I can just pass the FormControl as input ? I'm confused.
html
<input
[placeholder]="placeholder"
[type]="type"
[(ngModel)]="value"
(keyup)="onChange()"
(change)="onChange()"
(blur)="onTouched()"
[disabled]="disabled"/>
ts
#Component({
selector: 'input-app',
templateUrl: './input.component.html',
providers: [
{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => InputComponent),
multi: true
}
]
})
export class InputComponent implements ControlValueAccessor {
#Input() type = 'text';
#Input() placeholder = 'placeholder';
#Input() errorMsg = '';
value: string;
disabled: boolean;
private onChangeFn;
private onTouchedFn;
writeValue(val: string | number): void {
this.value = val;
}
registerOnChange(fn: any): void {
this.onChangeFn = fn;
}
registerOnTouched(fn: any): void {
this.onTouchedFn = fn;
}
setDisabledState?(isDisabled: boolean): void {
this.disabled = isDisabled;
}
onChange(){
this.onChangeFn(this.value);
}
onTouched(){
this.onTouchedFn();
}
}

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.

Is it Possible to nest FormGroups inside each other in Angular2?

I want to define a Form which consists of FormControls and FormGroups.
But i receive the following Error if i add the optionalInputGroup:
TypeError: this.form._updateTreeValidity is not a function
at FormGroupDirective._updateDomValue (http://localhost:8100/build/main.js:30206:19)
at FormGroupDirective.ngOnChanges (http://localhost:8100/build/main.js:30065:18)
at Wrapper_FormGroupDirective.ngDoCheck (/ReactiveFormsModule/FormGroupDirective/wrapper.ngfactory.js:30:18)
at CompiledTemplate.proxyViewClass.View_ConfiguratorOptionalGroupInputComponent0.detectChangesInternal (/AppModule/ConfiguratorOptionalGroupInputComponent/component.ngfactory.js:397:32)
at CompiledTemplate.proxyViewClass.AppView.detectChanges (http://localhost:8100/build/main.js:134498:14)
at CompiledTemplate.proxyViewClass.DebugAppView.detectChanges (http://localhost:8100/build/main.js:134693:44)
at CompiledTemplate.proxyViewClass.AppView.internalDetectChanges (http://localhost:8100/build/main.js:134483:18)
at View_ConfiguratorPage5.detectChangesInternal (/AppModule/ConfiguratorPage/component.ngfactory.js:245:19)
at View_ConfiguratorPage5.AppView.detectChanges (http://localhost:8100/build/main.js:134498:14)
at View_ConfiguratorPage5.DebugAppView.detectChanges (http://localhost:8100/build/main.js:134693:44)
at ViewContainer.detectChangesInNestedViews (http://localhost:8100/build/main.js:134830:37)
at View_ConfiguratorPage1.detectChangesInternal (/AppModule/ConfiguratorPage/component.ngfactory.js:369:14)
at View_ConfiguratorPage1.AppView.detectChanges (http://localhost:8100/build/main.js:134498:14)
at View_ConfiguratorPage1.DebugAppView.detectChanges (http://localhost:8100/build/main.js:134693:44)
at ViewContainer.detectChangesInNestedViews (http://localhost:8100/build/main.js:134830:37)
I create my FormConfig with the following Method:
flattenConfigForForm(inputs: [AbstractConfiguratorControl], returnObject = {}): Object {
inputs.map(input => {
switch (input.type) {
case ConfigurationInputType.Group:
let groupInput: ConfiguratorInputGroup = <ConfiguratorInputGroup> input;
returnObject[groupInput.key] = groupInput;
break;
default:
let basicInput: ConfiguratorInput = <ConfiguratorInput> input;
returnObject[basicInput.key] = basicInput;
returnObject[basicInput.key + ".ion"] = basicInput.value;
}
});
return returnObject;
}
where ConfigurationInputType.Group is an instance of FormGroup with an inputs-Attribute which itself contains FormControls and default is an instance of FormControl.
This is how i build my form in html, where values is the FormGroup which was created by flattenConfigForForm.
<form [formGroup]="values" (ngSubmit)="logForm()">
<div class="requiredInputs">
<div *ngFor="let input of config.inputs">
<configurator-number-input [passedFormGroup]="values" *ngIf="isEqualType(input.type,configInputType.Number)"
formControlName="{{input.key}}"></configurator-number-input>
<configurator-toggle-input [passedFormGroup]="values" *ngIf="isEqualType(input.type,configInputType.Toggle)"
formControlName="{{input.key}}"></configurator-toggle-input>
<configurator-select-input [passedFormGroup]="values" *ngIf="isEqualType(input.type,configInputType.Select)"
formControlName="{{input.key}}"></configurator-select-input>
<configurator-optional-group-input formGroupName="{{input.key}}" [passedFormGroup]="input"
formControlName="{{input.key}}"
*ngIf="isEqualType(input.type,configInputType.Group)"></configurator-optional-group-input>
</div>
</div>
</form>
this is my formGroupInputComponent.html
<div [formGroup]="passedFormGroup">
<ion-input>
<ion-checkbox [(ngModel)]="input.enabled"></ion-checkbox>
</ion-input>
<div *ngFor="let subinput of input.inputs">
<configurator-number-input [passedFormGroup]="input" *ngIf="isEqualType(subinput.type,configInputType.Number)"
formControlName="{{subinput.key}}"></configurator-number-input>
<configurator-toggle-input [passedFormGroup]="input" *ngIf="isEqualType(subinput.type,configInputType.Toggle)"
formControlName="{{subinput.key}}"></configurator-toggle-input>
<configurator-select-input [passedFormGroup]="input" *ngIf="isEqualType(subinput.type,configInputType.Select)"
formControlName="{{subinput.key}}"></configurator-select-input>
</div>
</div>
and this is my formGroupInput.ts
#Component({
selector: 'configurator-optional-group-input',
templateUrl: 'configurator-optional-group-input.html',
providers: [
{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => ConfiguratorOptionalGroupInputComponent),
multi: true,
}
]
})
export class ConfiguratorOptionalGroupInputComponent implements ControlValueAccessor {
input: ConfiguratorInputGroup;
#Input() public passedFormGroup: FormGroup;
// the method set in registerOnChange, it is just
// a placeholder for a method that takes one parameter,
// we use it to emit changes back to the form
private propagateChange = (_: any) => {
};
constructor() {
}
//ControlValueAccessor
writeValue(obj: any): void {
if (obj) {
console.log(this.passedFormGroup);
this.input = <ConfiguratorInputGroup> obj;
}
}
registerOnChange(fn: any): void {
this.propagateChange = fn;
}
// not used, used for touch input
registerOnTouched(fn: any): void {
}
}
Thanks in advance!

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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