I am trying to subscribe Observable in a function. But it is not triggering.
resetShippingForm(): void {
this.resetForm$ =
this.assemblyItemService.resetSUForm$.asObservable();
this.resetForm$.subscribe(data => {
if (data) {
console.log(data);
}
});
}
Make sure resetSUForm subject observer is feed value using next(value) method and call resetShippingForm() inside constructor/ngOnInit.
Related
I am trying to display a routerlink name based on a condition. I want to display the div section routerLink name if condition is true.If i check {{isNameAvailable}}, first it displays false and after this.names got the values it shows true.Since in the component getDetails() method is asynchronous this.names getting the values after html template render.Therefore this routerLink does n't display.Therefore I want to display div section after some time. (That 's the solution i have) Don't know whether is there any other solution.
This is my html file code.
<main class="l-page-layout ps-l-page-layput custom-scroll bg-white">
{{isNameAvailable}}
<div class="ps-page-title-head" >
<a *ngIf ="isNameAvailable === true" [routerLink]="['/overview']">{{Name}}
</a>
{{Name}}
</div>
</main>
This is my component.ts file
names= [];
isNameAvailable = false;
ngOnInit() {
this.getDetails()
}
getDetails() {
this.route.params.subscribe(params => {
this.names.push(params.Names);
console.log(this.names);
this.getValues().then(() => {
this.isNameAvailable = this.checkNamesAvailability(this.names);
console.log(this.isNameAvailable);
});
});
}
resolveAfterSeconds(x) {
return new Promise(resolve => {
setTimeout(() => {
resolve(x);
}, 900);
});
}
checkNamesAvailability(names) {
console.log(names);
return names.includes('Sandy');
}
async getValues() {
await this.resolveAfterSeconds(900);
}
And console.log(this.isLevelAvailable); also true. What I can do for this?
1.You do not have anything to show in the HTML only the isNameAvailable, because you do not have any assignment in the Name variable.
2.It is better to use the angular build-in async pipe,
when you want to show the returned value from observables.
3.When you are using the *ngIf directive you can skip *ngIf ="isNameAvailable === true" check because the variable is boolean type, you gust write *ngIf ="isNameAvailable", it will check also for null but NOT for undefined
It is working because the *ngIf directive is responsible for checking and rendering the UI, you can see how many times the directive is checking by calling an function and print and answer in the console.
By any chance do you have changeDetection: ChangeDetectionStrategy.OnPush docs set in component annotation? That might explain this behaviour. With it Angular run change detection only on component #Input()'s changes and since in your case there were non it did not run change detection which is why template was not updated. You could comment that line to check if that was cause of the issue. You are always able to run change detection manually via ChangeDetectorRef.detectChange() docs which should solve you problem
constructor(private cd: ChangeDetectorRef) {}
...
getDetails() {
this.route.params.subscribe(params => {
...
this.getValues().then(() => {
this.isNameAvailable = this.checkNamesAvailability(this.names);
this.cd.detectChanges(); // solution
console.log(this.isNameAvailable);
});
});
}
This stackblitz show this bug and solution. You can read more about change detection here
You could use RxJS timer function with switchMap operator instead of a Promise to trigger something after a specific time.
Try the following
import { Subject, timer } from 'rxjs';
import { takeUntil, switchMap } from 'rxjs/operators';
names= [];
isNameAvailable = false;
closed$ = new Subject();
ngOnInit() {
this.getDetails()
}
getDetails() {
this.route.params.pipe(
switchMap((params: any) => {
this.names.push(params.Names);
return timer(900); // <-- emit once after 900ms and complete
}),
takeUntil(this.closed$) // <-- close subscription when `closed$` emits
).subscribe({
next: _ => {
this.isNameAvailable = this.checkNamesAvailability(this.names);
console.log(this.isNameAvailable);
}
});
}
checkNamesAvailability(names) {
console.log(names);
return names.includes('Sandy');
}
ngOnDestroy() {
this.closed$.next(); // <-- close open subscriptions when component is closed
}
I am trying to run getResponse once when a web components finishes loading. However, when I try to run this, the debounce function just acts as an async delay and runs 4 times after 5000 ms.
static get properties() {
return {
procedure: {
type: String,
observer: 'debounce'
}
}
}
debounce() {
this._debouncer = Polymer.Debouncer.debounce(this._debouncer, Polymer.Async.timeOut.after(5000), () => {
this.getResponse();
});
}
getResponse() {
console.log('get resp');
}
What is necessary to get getResponse to run once upon the loading of the element?
Are you sure you want to use a debouncer for that? you could just use the connectedCallBack to get a one Time Event
class DemoElement extends HTMLElement {
constructor() {
super();
this.callStack = 'constructor->';
}
connectedCallback() {
this.callStack += 'connectedCallback';
console.log('rendered');
fetch(this.fakeAjax()).then((response) => {
// can't do real ajax request here so we fake it... normally you would do
// something like this.innerHTML = response.text();
// not that "rendered" get console logged before "fetch done"
this.innerHTML = `
<p>${this.callStack}</p>
<p>${response.statusText}</p>
`;
console.log('fetch done');
}).catch(function(err) {
console.log(err); // Error :(
});
}
fakeAjax() {
return window.URL.createObjectURL(new Blob(['empty']));
};
}
customElements.define('demo-element', DemoElement);
<demo-element></demo-element>
If you really need to use an observer you could also set a flag this.isLoaded in your connectedCallback() and check for that in your observer code.
I am trying to pass data to a child component and I keep getting an undefined prop. I think it may have an issue with when Im setting the state in the parent component. Should i not be using componentWillMount?
export default class AllItems extends Component {
constructor () {
super()
this.state=({ user: cookie.load('user')})
this.httpHandler = axios.create({
baseURL: 'http://localhost:3000/',
headers: {
'Authorization': this.state.user.token
}
})
}
componentWillMount() {
this.httpHandler('/products/')
.then(function (response) {
this.setState({ winks: response.data.data})
console.log(this.state.winks)
}.bind(this))
}
render() {
return (
<Winks products={this.state.winks} />
)
}
}
The problem is that your promise may not return before componentWillMount finishes and render is called. So products won't exist yet. You could do something like this:
render() {
if (this.state.winks) {
return (<Winks products={this.state.winks} />)
} else {
return (<div>No Winks yet</div>);
}
}
the problem is that you do not have an initial state for winks Since you are relying on an ajax call to set the state of winks, the ajax call will take place asynchronously and then it will execute the render function before the api call finishes causing this.state.winks to be undefined initially.
You could do something like this
render() {
let content = this.state.winks ? <Winks products={this.state.winks} /> : <div/>
return <div> {content} </div>
When using a generic modal or toast with a confirm button, it becomes useful to be able to pass an action into this component so it can be dispatched when you click confirm.
The action may look something like this:
export function showConfirm({modalConfirm}) {
return {
type: 'MODALS/SHOW_MODAL',
payload: {
modalId: getUuid(),
modalType: 'CONFIRM',
modalConfirm : modalConfirm,
},
};
}
Where modalConfirm is another action object such as:
const modalConfirm = {
type: 'MAKE_SOME_CHANGES_AFTER_CONFIRM',
payload: {}
}
The modalConfirm action is dispatched inside the modal component using dispatch(modalConfirm) or even dispatch(Object.assign({}, modalConfirm, someResultFromTheModal)
Unfortunatley this solution only works if modalConfirm is a simple redux action object. This system is clearly very limited. Is there anyway you can pass a function (such as a thunk) in instead of a simple object?
Ideally, something full featured likes this:
const modalConfirm = (someResultFromTheModal) => {
return (dispatch, getState){
dispatch({
type: 'MAKE_SOME_UPDATES',
payload: someResultFromTheModal
})
dispatch({
type: 'SAVE_SOME_STUFF',
payload: http({
method: 'POST',
url: 'api/v1/save',
data: getState().stuffToSave
})
})
}
}
Funny, putting an action object in the store and passing it as a prop to a generic dialog is exactly the approach I came up with myself. I've actually got a blog post waiting to be published describing that idea.
The answer to your question is "Yes, but....". Per the Redux FAQ at http://redux.js.org/docs/FAQ.html#organizing-state-non-serializable , it's entirely possible to put non-serializable values such as functions into your actions and the store. However, that generally causes time-travel debugging to not work as expected. If that's not a concern for you, then go right ahead.
Another option would be to break your modal confirmation into two parts. Have the initial modal confirmation still be a plain action object, but use a middleware to watch for that being dispatched, and do the additional work from there. This is a good use case for Redux-Saga.
I ended up using string aliases to an actions library that centrally registers the actions.
Modal emmiter action contains an object with functionAlias and functionInputs
export function confirmDeleteProject({projectId}) {
return ModalActions.showConfirm({
message: 'Deleting a project it permanent. You will not be able to undo this.',
modalConfirm: {
functionAlias: 'ProjectActions.deleteProject',
functionInputs: { projectId }
}
})
}
Where 'ProjectActions.deleteProject' is the alias for any type of complicated action such as:
export function deleteProject({projectId}) {
return (dispatch)=>{
dispatch({
type: 'PROJECTS/DELETE_PROJECT',
payload: http({
method: 'DELETE',
url: `http://localhost:3000/api/v1/projects/${projectId}`,
}).then((response)=>{
dispatch(push(`/`))
}),
meta: {
projectId
}
});
}
}
The functions are registered in a library module as follows:
import * as ProjectActions from '../../actions/projects.js';
const library = {
ProjectActions: ProjectActions,
}
export const addModule = (moduleName, functions) => {
library[moduleName] = functions
}
export const getFunction = (path) => {
const [moduleName, functionName] = path.split('.');
// We are getting the module only
if(!functionName){
if(library[moduleName]){
return library[moduleName]
}
else{
console.error(`Module: ${moduleName} could not be found.`);
}
}
// We are getting a function
else{
if(library[moduleName] && library[moduleName][functionName]){
return library[moduleName][functionName]
}
else{
console.error(`Function: ${moduleName}.${functionName} could not be found.`);
}
}
}
The modalConfirm object is passed in to the modal by props. The modal component requires the getFunction function in the module above. The modalConfirm object is transformed into a function as follows:
const modalConfirmFunction = (extendObject, modalConfirm) => {
const functionFromAlias = getFunction(modalConfirm.functionAlias);
if(functionFromAlias){
dispatch(functionFromAlias(Object.assign({}, modalConfirm.functionInputs, extendObject)));
}
}
As you can see, this function can take in inputs from the modal. It can execute any type of complicated action or thunk. This system does not break time-travel but the centralized library is a bit of a drawback.
I need a way to catch the JSON response every time my datastore has loaded. My first try was to use the autoLoad property but the callback fires only on first load :
autoLoad: {
callback: function (records, operation) {
// do something with operation.response.responseText
}
}
So, I have decided to extend the load method :
load: function (options) {
var callback = options && options.callback;
return this.callParent([Ext.apply(options || {}, {
callback: function (records, operation) {
// do something with operation.response.responseText
if (callback) {
return callback.apply(this, arguments);
}
}
})]);
}
It works, but I wonder if the framework already provides a more elegant solution.
You can add a load listener to the store and grab the current request from it's proxy when the load event is fired.
var myStore = Ext.create("Ext.data.store", {
...whatever here
listeners: {
load: function(store){
store.getProxy().activeRequest.options.operation.response.responseText;
}
}
});
Thats if you want the response text specifically. If you want the response as a JSON object, you can use store.getProxy().reader.rawData; which is a little simpler