I was wondering if the mobx cycle is triggered on observable change only in stores outside of react components in HOClass operation
because there is a top level Provider to mobx stores which is triggering a react component re-render.
ReactDOM.render(<Provider { ...stores } >
<Routes />
</Provider>,
But does that mean I can't add observables directly to react components?
if so that is a bit unfortunate.
#observer
export default class Profile extends React.Component {
#observable name;
componentWillMount() {
this.name = this.props.name;
}
txtChange = (e) => {
this.name = e.target.value;
}
render() {
return (
<div>
<input type="text" onChange={this.txtChange} value={this.name}/>
</div>
)
}
for some reason on my app I cannot update the observable name. On some apps using mobx however I can. Why am I unable to change the value of this and trigger a react state update if the observable is attached to the React.Component itself?
Here I have forms updating in controlled observable fashion but when Provider 'ing my router on my current project under this setup no react rerender is triggered.
https://codepen.io/cheapsteak/pen/wzdvzQ
Help anyone?
There (was) a typo: the function is called txtChange but the component references this.txthange instead. Either way, here's a fixed working example: https://codepen.io/justnobody/pen/RxJmmY?editors=1010
I'm trying to create a custom form control in Angular (v5). The custom control is essentially a wrapper around an Angular Material component, but with some extra stuff going on.
I've read various tutorials on implementing ControlValueAccessor, but I can't find anything that accounts for writing a component to wrap an existing component.
Ideally, I want a custom component that displays the Angular Material component (with some extra bindings and stuff going on), but to be able to pass in validation from the parent form (e.g. required) and have the Angular Material components handle that.
Example:
Outer component, containing a form and using custom component
<form [formGroup]="myForm">
<div formArrayName="things">
<div *ngFor="let thing of things; let i = index;">
<app-my-custom-control [formControlName]="i"></app-my-custom-control>
</div>
</div>
</form>
Custom component template
Essentially my custom form component just wraps an Angular Material drop-down with autocomplete. I could do this without creating a custom component, but it seems to make sense to do it this way as all the code for handling filtering etc. can live within that component class, rather than being in the container class (which doesn't need to care about the implementation of this).
<mat-form-field>
<input matInput placeholder="Thing" aria-label="Thing" [matAutocomplete]="thingInput">
<mat-autocomplete #thingInput="matAutocomplete">
<mat-option *ngFor="let option of filteredOptions | async" [value]="option">
{{ option }}
</mat-option>
</mat-autocomplete>
</mat-form-field>
So, on the input changing, that value should be used as the form value.
Things I've tried
I've tried a few ways of doing this, all with their own pitfalls:
Simple event binding
Bind to keyup and blur events on the input, and then notify the parent of the change (i.e. call the function that Angular passes into registerOnChange as part of implementing ControlValueAccessor).
That sort of works, but on selecting a value from the dropdown it seems the change events don't fire and you end up in an inconsistent state.
It also doesn't account for validation (e.g. if it's "required", when a value isn;t set the form control will correctly be invalid, but the Angular Material component won't show as such).
Nested form
This is a bit closer. I've created a new form within the custom component class, which has a single control. In the component template, I pass in that form control to the Angular Material component. In the class, I subscribe to valueChanges of that and then propagate the changes back to the parent (via the function passed into registerOnChange).
This sort of works, but feels messy and like there should be a better way.
It also means that any validation applied to my custom form control (by the container component) is ignored, as I've created a new "inner form" that lacks the original validation.
Don't use ControlValueAccessor at all, and instead just pass in the form
As the title says... I tried not doing this the "proper" way, and instead added a binding to the parent form. I then create a form control within the custom component as part of that parent form.
This works for handling value updates, and to an extent validation (but it has to be created as part of the component, not the parent form), but this just feels wrong.
Summary
What's the proper way of handling this? It feels like I'm just stumbling through different anti-patterns, but I can't find anything in the docs to suggest that this is even supported.
Edit:
I've added a helper for doing just this an angular utilities library I've started: s-ng-utils. Using that you can extend WrappedFormControlSuperclass and write:
#Component({
selector: 'my-wrapper',
template: '<input [formControl]="formControl">',
providers: [provideValueAccessor(MyWrapper)],
})
export class MyWrapper extends WrappedFormControlSuperclass<string> {
// ...
}
See some more documentation here.
One solution is to get the #ViewChild() corresponding to the inner form components ControlValueAccessor, and delegating to it in your own component. For example:
#Component({
selector: 'my-wrapper',
template: '<input ngDefaultControl>',
providers: [
{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => NumberInputComponent),
multi: true,
},
],
})
export class MyWrapper implements ControlValueAccessor {
#ViewChild(DefaultValueAccessor) private valueAccessor: DefaultValueAccessor;
writeValue(obj: any) {
this.valueAccessor.writeValue(obj);
}
registerOnChange(fn: any) {
this.valueAccessor.registerOnChange(fn);
}
registerOnTouched(fn: any) {
this.valueAccessor.registerOnTouched(fn);
}
setDisabledState(isDisabled: boolean) {
this.valueAccessor.setDisabledState(isDisabled);
}
}
The ngDefaultControl in the template above is to manually trigger angular to attach its normal DefaultValueAccessor to the input. This happens automatically if you use <input ngModel>, but we don't want the ngModel here, just the value accessor. You'll need to change DefaultValueAccessor above to whatever the value accessor is for the material dropdown - I'm not familiar with Material myself.
I'm a bit late to the party but here is what I did with wrapping a component which might accept formControlName, formControl, or ngModel
#Component({
selector: 'app-input',
template: '<input [formControl]="control">',
styleUrls: ['./app-input.component.scss']
})
export class AppInputComponent implements OnInit, ControlValueAccessor {
constructor(#Optional() #Self() public ngControl: NgControl) {
if (this.ngControl != null) {
// Setting the value accessor directly (instead of using the providers) to avoid running into a circular import.
this.ngControl.valueAccessor = this;
}
}
control: FormControl;
// These are just to make Angular happy. Not needed since the control is passed to the child input
writeValue(obj: any): void { }
registerOnChange(fn: (_: any) => void): void { }
registerOnTouched(fn: any): void { }
ngOnInit() {
if (this.ngControl instanceof FormControlName) {
const formGroupDirective = this.ngControl.formDirective as FormGroupDirective;
if (formGroupDirective) {
this.control = formGroupDirective.form.controls[this.ngControl.name] as FormControl;
}
} else if (this.ngControl instanceof FormControlDirective) {
this.control = this.ngControl.control;
} else if (this.ngControl instanceof NgModel) {
this.control = this.ngControl.control;
this.control.valueChanges.subscribe(x => this.ngControl.viewToModelUpdate(this.control.value));
} else if (!this.ngControl) {
this.control = new FormControl();
}
}
}
Obviously, don't forget to unsubscribe from this.control.valueChanges
I have actually been wrapping my head around this for a while and I figured out a good solution that is very similar (or the same) as Eric's.
The thing he forgot to account for, is that you can't use the #ViewChild valueAccessor until the view has actually loaded (See #ViewChild docs)
Here is the solution: (I am giving you my example which is wrapping a core angular select directive with NgModel, since you are using a custom formControl, you will need to target that formControl's valueAccessor class)
#Component({
selector: 'my-country-select',
templateUrl: './country-select.component.html',
styleUrls: ['./country-select.component.scss'],
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: CountrySelectComponent,
multi: true
}]
})
export class CountrySelectComponent implements ControlValueAccessor, OnInit, AfterViewInit, OnChanges {
#ViewChild(SelectControlValueAccessor) private valueAccessor: SelectControlValueAccessor;
private country: number;
private formControlChanged: any;
private formControlTouched: any;
public ngAfterViewInit(): void {
this.valueAccessor.registerOnChange(this.formControlChanged);
this.valueAccessor.registerOnTouched(this.formControlTouched);
}
public registerOnChange(fn: any): void {
this.formControlChanged = fn;
}
public registerOnTouched(fn: any): void {
this.formControlTouched = fn;
}
public writeValue(newCountryId: number): void {
this.country = newCountryId;
}
public setDisabledState(isDisabled: boolean): void {
this.valueAccessor.setDisabledState(isDisabled);
}
}
NgForm is providing an easy way to manage your forms without injecting any data in a HTML form. Input data must be injected at the component level not in a classic html tag.
<form #myForm="ngForm" (ngSubmit)="onSubmit(myForm)>...</form>
Other way is to create a form component where all the data model is binded using ngModel ;)
I have a component which is a form, with a number of child components. What is the best way to consolidate the data from all of the child components, when submitting the form? Below is one idea, is this the correct method? I pass a reference to a function that will update a property of a form upon change in a component. What is best practice? Thanks.
import React from 'react';
import { Component , PropTypes} from 'react';
import { connect } from 'react-redux';
import { saveData } from '../actions/index'
import {bindActionCreators} from 'redux';
export default class MyClass extends Component {
constructor(props) {
super (props);
this.formData = {};
this.setFormData = this.setFormData.bind(this);
this.onSubmitHandler = this.onSubmitHandler.bind(this);
}
setFormData(key, value){
this.formData[key] = value;
}
onSubmitHandler(evt){
this.props.saveData(this.formData);
}
render (){
return (
<div>
<form onSubmit = {this.onSubmitHandler} >
<div >
<NameComponent setFormData = {this.setFormData}/>
<AddressComponent setFormData = {this.setFormData}/>
//...lots more components
</form>
</div>
);
}
}
export default connect( mapStateToProps, {saveData)(MyClass)
Yes, this approach is correct, because children are generally expected to delegate to parent that is responsible for them. In fact, that's how Redux Form works. <Field /> input components delegate their state to a Higher Order <Form /> wrapper.
The problem with your approach is that you have to do a lot of repetitive stuff on your own (such as calling onChange, delegating the value etc).
We use Redux Form for one of our projects and it's great as it integrates forms, react and redux. I find myself writing much less code and there is build in validation for both remote, local submission, submission from child components and other neat stuff.
My suggestion is to go with Redux Form instead of reinventing the wheel.
Originally, I had it working fine.
Then I did this and now I can't get it to work
ClipboardField.js
import React from 'react';
export default (props) => {
return(
<div id="clip" data-clipboard-text={props.code} onClick={props.onClick}>
<p> Copy to clipboard.</p>
</div>
);
}
Field.js
class DashWizardTwoCore extends Component {
componentDidMount(){
const btns = document.getElementById('clip');
const clipboard = new Clipboard(btns);
}
componentDidUpdate() {
clipboard.on('success', function(e) {
console.log(e);
});
clipboard.on('error', function(e) {
console.log(e);
});
}
render(){
const someCode = "const foo = 1"
return (
<div>
<ClipboardField code={this.someCode} /> }
</div>
);
}
}
If you take the code out of ClipboardField and into Field it works. It's mostly, how do I use document.getElementById() in my parent component to find something in my child?
Their examples:
https://github.com/zenorocha/clipboard.js/blob/master/demo/constructor-selector.html#L18
https://github.com/zenorocha/clipboard.js/blob/master/demo/constructor-node.html#L16-L17
https://github.com/zenorocha/clipboard.js/blob/master/demo/constructor-nodelist.html#L18-L19
Your code is fine you just have a few issues:
you are binding clipboard.on in componentDidUpdate which won't trigger here since you are not really changing anything (in the ClipboardField component) that triggers this event.
You are passing {this.someCode} in the code prop which would be undefined should just be {someCode}
So it's just a matter of moving your clipboard.on to the componentDidMount right after the new Clipboard and use code={someCode}
https://jsfiddle.net/yy8cybLq/
--
In React whenever you want to access the actual dom element of your component we use what react calls as refs, I would suggest you do this rather than using getElementById as this is the "best practice".
However stateless components (like your ClipboardField component above) can't have refs so you just need to change it to be a normal component.
Here's a fiddle with your code but using refs instead: https://jsfiddle.net/e5wqk2a2/
I tried including links to the react docs for stateless components and refs but apparently don't have enough "rep" to post more than 2 links, anyways quick google search should point you in the right direction.
I adjusted your code and created a simple integration of clipboard.js with React.
Here's the fiddle: https://jsfiddle.net/mrlew/ehrbvkc1/13/ . Check it out.
Inspecting toggles on http://www.material-ui.com/#/components/toggle there is an input tag of type 'checkbox' in DOM. 'Toggled by default' has attribute 'checked' but when I turn it to OFF state then attributes in underling 'input' tag does not change and 'checked' is still present.
How to determine toggle ON/OFF state from DOM?
p.s.
I am writing automated functional tests using Selenium web driver.
If you can assign a custom data-* prop to each toggle, try this:
handleToggle = (event) => {
// here's your checked Value
event.target.getAttribute('data-isToggled')
}
// ...React boilerplate
<Toggle
label="Toggled by default"
onToggle={this.handleToggle}
data-isToggled={this.state.Toggled}
toggled={this.state.Toggled}
/>
You don't directly check toggle state from the DOM. You have to use javascript callbacks to determine if a toggle switch is on or off.
Class ToggleComponent Example
export default class ToggleComponent extends React.Component {
constructor(props) {
super(props);
this.state = {Toggled: true};
}
handleToggle() {
this.setState({Toggled: !this.state.Toggled});
console.log(this.state.Toggled)
}
render() {
return (
<div>
<Toggle
label="Toggled by default"
defaultToggled={this.state.Toggled}
onToggle={this.handleToggle.bind(this)}
toggle={this.state.Toggled}
/>
</div>
);
}
}
Look at: https://facebook.github.io/react/docs/interactivity-and-dynamic-uis.html