I am using angular for my web app and i need bluetooth on one of my pages.
I am using loginov-rocks/bluetooth-terminal(https://github.com/loginov-rocks/bluetooth-terminal) for the bluetooth connection and it works i can conect my device and see data from it. now the problem i have is i cannot get the data from my recieve function to my angular component, i can print data to console, but that is not what i want, i want to parse my data and set some variables in my angular component from it.Here is my code:
let bluetooth = new BluetoothTerminal();
bluetooth.receive = function (data) {
console.log(data);
//i want to call ParseBtData here from my angular component to parse data
//or somehow send data and cach it for parsing inside my component
};
export class GpsAppComponent extends AppComponentBase implements OnInit
{
//all the angular stuff
parseBtData(data) {
//parse my BT data and set some variables inside my component...
};
}
I have tryed making BluetoothTerminal inside the component, but i still cannot call any function to parse my data. Is it even possible to do that, or is there another way i should aproach my problem?
In general if you create an object javascript you can do it using declare, then the only is override the "received" data. But a change because an event not controlle by Angular, you need say to Angular that "something" has changed outside Angular, so you need use ngZone, some like:
//DISCLAMER: I don't know if work
declare var bluetooth = new BluetoothTerminal();
export class AppComponent implements AfterViewInit
{
constructor(private ngZone:NgZone,private dataService:DataService){}
ngAfterViewInit(){
bluetooth.receive = (data)=> {
this.ngZone.run(()=>{
this.dataService.sendData(data)
})
};
}
}
Then you only need define in your service
bluethoodData:Subject<any>=new Subject<any>()
sendData(data:any)
{
this.bluethoodData.next(data)
}
And you can subscribe in any component to dataService.bluethoodData
this.dataService.bluethoodData.subscribe(res=>{
console.log(res)
})
I managed to solve my problem by moving my bluetooth inside the component and doing:
this.bluetooth.receive = (data) => {
//console.log(data);
this.writeToTerminalConsole(data);
};
Related
I cant seem to figure out what the issue is,
I have a service that has a behavior subject like so...
popupSource = new BehaviorSubject<any>('');
popup(component) {
this.popupSource.next(component);
}
then In my header component
popupClick() {
this._service.popup('example');
}
then in my header.html
<button (click)="popupClick()"></button>
then In my app component
ngOnInit() {
this._service.popupSource.subscribe((result) => {
console.log(result);
})
}
so whats happening is the click is firing the this._service.popup('example'); but its never hitting the subscription...
I've put breakpoints on each function and It succesfully reaches this.popupSource.next(component) but then nothing?? Every Time I click the button I should be getting the console log.
Im not sure what Im doing wrong... Ive left out code for brevity sake so please let me know if you need more information
EDIT
Ive also tried doing
private popupSource = new BehaviorSubject<any>('');
getPopup = this.popupSource.asObservable();
popup(component) {
this.popupSource.next(component);
}
and the in my app component listend to the getPopup instead
ngOnInit() {
this._service.getPopup.subscribe((result) => {
console.log(result);
})
}
and that's not working either, I cant figure out what the problem is...
Thanks
Your issue here is that you provide your service in two different modules, that end up with two instances of your service. The simplest way if you are using Angular v6 is to use the providedIn flag in your service:
import { Injectable } from '#angular/core';
#Injectable({providedIn: 'root'})
class myService {}
With this way you don't need to provide your service in the providers array of any module, it will be automatically provided in the root injector.
Documentation about this can be found here : Angular providers.
If your are using Angular v5 you should only provide your service in your AppModule.
In your service, write a new method like this:
popupSource = new BehaviorSubject<any>('');
getPopupSource() {
return this.popupSource.asObservable();
}
And subscribe to that instead of subscribing directly to the subject itself. You could just add the 'asObservable()' part whenever you subscribe to it instead of creating an entirely new method, but I like the separate method so I can keep the Subject private, and I usually subscribe to something multiple times in different places throughout an app, so it cuts down on repetition.
In your component :
this._service.getPopupSource().subscribe( result => { etc...})
EDIT :
Demo recreation of your scenario - https://stackblitz.com/edit/angular-n6esd5
You may not have the same instance of service, my same problem was that I had #Injectable({ providedIn: 'root'}) for my service, but also I put this service in the component providers [] array, just remove the providers array, then it works
Is it even possible to let a service call an component Method?
myapp.component
export class MyAppComponent {
public value;
...
public setValue(payload){
this.value = payload;
}
}
myapp.service
#Injectable()
export class MyAppService {
private myAppComponent: MyAppComponent;
private apiClientService: ApiClientService
// ...
After i make an PUT http call, the body from the response is my new "value"
// ...
putValue(payload: JSON){
return this.apiClientService.putAPIObject(payload).then((response) => {
this.myAppComponent.setValue(response);
});
}
}
This results in an ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'setValue' of undefined.
Can someone explain what im doing wrong?
Thanks in advance.
EDIT:
Since people complain about my approach, im totally fine to start from scratch if someone can explain me what is the best way to handle this problem.
I get values from an api, change them and i put them back to the api. I dont want to make a get call again, so i get the new data i want in the response of the Put call.
The call goes from component --> component service --> apiclient service
I guess the problem is that i have an extra service between the start and end point.
EDIT 2: I tried to avoid the component service and maked it work for me with only component --> apiclient service
Even this soultion is working for me at the moment I kind of dislike it, because I have to Copy and Paste a lot of code for the Same "Operation" with other objects from my api. For example I maked it work for the Picture Component, but I also need this for my Movie Component. Usally its a bad thing if I write the same code often in a project, or not?
There are at least a couple ways to solve this, but hopefully this gives you a start. Open to feedback and corrections.
Use an Observable
Let the service own knowledge of the value changes and emit changes. The component listens to an EventEmitter on1 the service to react to value changes. (See also: Creating and returning Observable from Angular 2 Service)
MyAppService
import { Subject } from 'rxjs/Subject';
#Injectable()
export class MyAppService {
private valueSource = new Subject<any>();
public valueUpdate$ = this.valueSource.asObservable();
putValue(payload: JSON){
return this.apiClientService.putAPIObject(payload).then((response) => {
/** here **/
this.valueUpdate$.next(response);
});
}
}
MyAppComponent
export class MyAppComponent {
public value;
private valueSubscription;
constructor(private _myAppService: MyAppService) {}
ngOnInit() {
/** and here **/
this._myAppService.valueUpdate$.subscribe((p) => this.setValue(p));
}
...
public setValue(payload){
this.value = payload;
}
}
Register the component
Answering the original question, the idea is to register the component with the service so that it can call the component as needed. You could pull a references through dependency injection but wouldn't recommend it (e.g. what if your original component reference is destroyed?)
MyAppService
#Injectable()
export class MyAppService {
private myAppComponent: MyAppComponent;
/** here **/
registerMyApp(myApp: MyAppComponent) {
this.myAppComponent = myApp;
}
putValue(payload: JSON){
return this.apiClientService.putAPIObject(payload).then((response) => {
this.myAppComponent.setValue(response);
});
}
}
MyAppComponent
export class MyAppComponent {
public value;
/** and here **/
constructor(myAppService: MyAppService) {
myAppService.registerMyApp(this);
}
...
public setValue(payload){
this.value = payload;
}
}
Thanks AJT_82 for noting that Angular does not want developers using EventEmitters on the service: What is the proper use of an EventEmitter?.
i am new in Angular 2 and trying to develop a project with basic CRUD functionality.
I am facing an issue that i have a User component and trying to access it's property in ngAfterViewInit hook, but it's showing undefined.
Here is code of User component.
export class UserComponent implements OnInit, AfterViewInit
{
private users: User[];
private userRoles;
ngOnInit(){
//get users from service
this.getUserDetails();
}
ngAfterViewInit() {
console.log(this);
console.log(this.users);
}
getUserDetails() {
this._userService.getUsers().subscribe(users => this.users = users);
}
}
Below is screen shots of console. I can see that Object has property users but it shows undefined in console.
Please give suggestion if i missed anything.
Thanks in advance.
Check user property inside getUserDetails. You can use users property in your template. Check component lifecycle hooks to get better idea about component lifecycle.
getUserDetails() {
this._userService.getUsers().subscribe((users) => {
this.users = users;
console.log(this.users);
});
}
I think this is not angular 2 issue...
This is typescript issue accessing this instance globally .
We can do this by using let and declaring variable in typescripts...
When javascript object assigned is cloned to other object then changes made to one is automatically passed to other
So this issue also arrises when we want to access typescript this object inside jquery functions
let _this = this;
something.each(function() {
console.log(_this); // the lexically scoped value
console.log(this); // the library passed value
});
I just started playing with angular 2 and i've ran into a small problem, that i ve searched for in various forms and also angulars documentation.
I've managed to make a service that makes a call and then i want in a component when i press a button to load another component with dynamicload component and have access to the ajax result.
The problem is that I can t figure out how to do that..
The question is how can I make the result accesible in other components using Observables or Promises method.
If I understood correctly your question, you are looking a way to insert a data from request to another nested component.
I hope this image will clarify for you the data flow for this case.
Your Root component is calling a service method which returns for you promise object.
Then you map needed data from response to the component model inside Root Component constructor.
And your Child component should be subscribed for the model which you was preparing in previous step.
ngOnInit() {
this.dataService.getSomeData()
.subscribe((data: IData) => {
this.data = data;
});
}
Just a short example above how to set model in the root component from the promise object to the local model.
New research:
There is another way to fill your components by data from api's. You can use EventEmitter to emit event from service, and then, you can subscribe for this event inside you created components, so they will get a data, each time there will be called the service. Here is nice example of this strategy in the first answer. Service Events
Hope it will help you, let me know if you will need additional info!
Just create a service, then inject the service where you want.
Here it's an example how to share a service ajax data across many components without making the request twice :
https://stackoverflow.com/a/36413003/2681823
the Service:
#Injectable()
export class DataService {
constructor(private http: Http) { }
private _dataObs = new ReplaySubject<request>(1);
getData(forceRefresh?: boolean) {
// On Error the Subject will be Stoped and Unsubscribed, if so, create another one
this._dataObs = this._dataObs.isUnsubscribed ? new ReplaySubject(1) : this._dataObs;
// If the Subject was NOT subscribed before OR if forceRefresh is requested
if (!this._dataObs.observers.length || forceRefresh) {
this.http.get('http://jsonplaceholder.typicode.com/posts/2')
.subscribe(
requestData => {
this._dataObs.next(requestData);
},
error => this._dataObs.error(error));
}
return this._dataObs;
}
}
the Component:
#Component({
selector: 'child',
template : `<button (click)="makeRequest()" class="btn">Click me!</button>`
})
export class Child {
constructor(private _dataService: DataService) { }
makeRequest() {
this._dataService.getData().subscribe(
requestData => {
console.log('ChildComponent', requestData);
}
}
}
A full working example/plunker can be found here : http://plnkr.co/edit/TR7cAqNATuygDAfj4wno?p=preview
I am currently working on porting a Backbone project to an Angular 2 project (obviously with a lot of changes), and one of the project requirements requires certain methods to be accessible publicly.
A quick example:
Component
#component({...})
class MyTest {
private text:string = '';
public setText(text:string) {
this.text = text;
}
}
Obviously, I could have <button (click)="setText('hello world')>Click me!</button>, and I would want to do that as well. However, I'd like to be able to access it publicly.
Like this
<button onclick="angular.MyTest.setText('Hello from outside angular!')"></click>
Or this
// in the js console
angular.MyTest.setText('Hello from outside angular!');
Either way, I would like the method to be publicly exposed so it can be called from outside the angular 2 app.
This is something we've done in backbone, but I guess my Google foo isn't strong enough to find a good solution for this using angular.
We would prefer to only expose some methods and have a list of public apis, so if you have tips for doing that as well, it'd be an added bonus. (I have ideas, but others are welcomed.)
Just make the component register itself in a global map and you can access it from there.
Use either the constructor or ngOnInit() or any of the other lifecycle hooks to register the component and ngOnDestroy() to unregister it.
When you call Angular methods from outside Angular, Angular doesn't recognize model change. This is what Angulars NgZone is for.
To get a reference to Angular zone just inject it to the constructor
constructor(zone:NgZone) {
}
You can either make zone itself available in a global object as well or just execute the code inside the component within the zone.
For example
calledFromOutside(newValue:String) {
this.zone.run(() => {
this.value = newValue;
});
}
or use the global zone reference like
zone.run(() => { component.calledFromOutside(newValue); });
https://plnkr.co/edit/6gv2MbT4yzUhVUfv5u1b?p=preview
In the browser console you have to switch from <topframe> to plunkerPreviewTarget.... because Plunker executes the code in an iFrame. Then run
window.angularComponentRef.zone.run(() => {window.angularComponentRef.component.callFromOutside('1');})
or
window.angularComponentRef.zone.run(() => {window.angularComponentRef.componentFn('2');})
This is how i did it. My component is given below. Don't forget to import NgZone. It is the most important part here. It's NgZone that lets angular understand outside external context. Running functions via zone allows you to reenter Angular zone from a task that was executed outside of the Angular zone. We need it here since we are dealing with an outside call that's not in angular zone.
import { Component, Input , NgZone } from '#angular/core';
import { Router } from '#angular/router';
#Component({
selector: 'example',
templateUrl: './example.html',
})
export class ExampleComponent {
public constructor(private zone: NgZone, private router: Router) {
//exposing component to the outside here
//componentFn called from outside and it in return calls callExampleFunction()
window['angularComponentReference'] = {
zone: this.zone,
componentFn: (value) => this.callExampleFunction(value),
component: this,
};
}
public callExampleFunction(value: any): any {
console.log('this works perfect');
}
}
now lets call this from outside.in my case i wanted to reach here through the script tags of my index.html.my index.html is given below.
<script>
//my listener to outside clicks
ipc.on('send-click-to-AT', (evt, entitlement) =>
electronClick(entitlement));;
//function invoked upon the outside click event
function electronClick(entitlement){
//this is the important part.call the exposed function inside angular
//component
window.angularComponentReference.zone.run(() =
{window.angularComponentReference.componentFn(entitlement);});
}
</script>
if you just type the below in developer console and hit enter it will invoke the exposed method and 'this works perfect ' will be printed on console.
window.angularComponentReference.zone.run(() =>
{window.angularComponentReference.componentFn(1);});
entitlement is just some value that is passed here as a parameter.
I was checking the code, and I have faced that the Zone is not probably necessary.
It works well without the NgZone.
In component constructor do this:
constructor(....) {
window['fncIdentifierCompRef'] = {
component = this
};
}
And in the root script try this:
<script>
function theGlobalJavascriptFnc(value) {
try {
if (!window.fncIdentifierCompRef) {
alert('No window.fncIdentifierCompRef');
return;
}
if (!window.fncIdentifierCompRef.component) {
alert('No window.fncIdentifierCompRef.component');
return;
}
window.fncIdentifierCompRef.component.PublicCmpFunc(value);
} catch(ex) {alert('Error on Cmp.PublicCmpFunc Method Call')}
}
</script>
This works to me.
The problem is that Angular's components are transpiled into modules that aren't as easy to access as regular JavaScript code. The process of accessing a module's features depends on the module's format.
An Angular2 class can contain static members that can be defined without instantiating a new object. You might want to change your code to something like:
#component({...})
class MyTest {
private static text: string = '';
public static setText(text:string) {
this.text = text;
}
}
Super simple solution!! save component or function with an alias outside
declare var exposedFunction;
#Component({
templateUrl: 'app.html'
})
export class MyApp {
constructor(public service:MyService){
exposedFunction = service.myFunction;
}
at index.html add in head
<script>
var exposedFunction;
</script>
Inside exposed function do not use this. parameters if you need them you will have to use closures to get it to work
This is particularly useful in ionic to test device notifications on web instead of device