You are defining your return type as Observable, but you are subscribing to the HTTP request. So, this is not connected with the updateTask() function from the view-task component. How to detect a change from one component into other. And indeed this has all worked solidly for many weeks, and only broke when I wiped out my local repo and re-cloned.. my angular/zone/rxjs dependencies all have fixed versions, so these can't have changed. Thanks to the efforts of Jan Recker I gained a much better understanding of what was happening there. To do that, I recommend you to visit the Angular official documentation. Using BehaviorSubject to Handle Asynchronous Loading in Ionic. Now the CountComponent has a Refresh button. You should do one thing or the other. What language(s) implements function return value by assigning to the function name. If that function change, the data change in both. // ReplaySubject is more flexible than BehaviorSubject, as it // allows you to define how many past emissions should be available. All subscribers share the same Observable execution. Change tokenRefreshInProgress status to true so that other interceptions will know that and do not trigger the refresh also; The refreshAccessTokenSubject BehaviorSubject gets set to null; Refresh the token and as soon as we get a result set the token; change the tokenRefreshInProgress to false; store the token in our BehaviorSubject. Tutorial built with Angular 10.1.6. Both of them, are connected to the task.service.ts, which will call the HTTP request. Wordpress on different environments with Versionpress. Watch later. My Backend is Django 3, using the Django Rest Framework and rest_framework_simplejwt. The example angular app has just two routes - a login page (/login) and a home page (/). RxJS version 5 is a peer dependency with Angular. Once you execute the command it will create an Angular 5 CLI project for you. For this demo, I have used Angular version 9. Use MathJax to format equations. rev 2021.1.18.38333, The best answers are voted up and rise to the top, Code Review Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us. Would have never thought of the potential stumbling block of the multiple interceptor instances as e.g. This is pretty unprofessional maybe, and I'm sure that there is a better approach to the same result. Here is the service: import { BehaviorSubject, Observable } from 'rxjs'; import { pluck } from 'rxjs/operators'; /** * Plain Store Service. A simple, but highly customizable, reactive state-management service is constructed on top of the RxJs BehaviorSubject. Now in the app.component.html file … See here for integration. What happened to the updateTask function? // But you can get an equivalent code with BehaviorSubject by // coding like this: // private _coachProfile$: BehaviorSubject = // new BehaviorSubject(null); private _coachProfile$: ReplaySubject = new ReplaySubject(1); coachProfile(token :string) { … Hope that nobody will add the HTTPClientModule ever somewhere else.       return this.http.patch(url, task, httpHaljson) To know more about how to create Angular 5 CLI project step by step, you can follow my previous article "Building Angular 5 CLI project with ngx-bootstrap". MathJax reference. If you have some experience with Angular, you’re probably familiar with Observables from RxJs. What could I "split off" into some nicely named function? And, here in the service, i do the HTTP request.   }. In theory you could try to have multiple event sources, combining them into one stream and handle the request manipulation there. A click on the Refresh button would instruct Angular to run the change detector, and, as a result of that, the view will be updated with the latest value of the counter. What could I be doing to make it more comprehensible?   private taskList: Task[]; Now, the getTasks() function, is not longer the same as before, now will check if our array is empty or not: getTasks() { I would always use access modifiers (public / private). Use a refresh token once our access token expires to get a new token for the next call; All of that needs some additional logic inside an interceptor, but let’s start with the basics. I followed all of his suggestions, but arrived at a different final code structure.             this.initializeTasks() What the interceptor is doing is check any outgoing HTTP request on if it's a call to my API. Rule of thumb is: If it's not officially documented, don't make any assumptions. export class TaskComponent {constructor (private readonly http: HttpClient) {} private readonly autoRefresh$ = interval (TASK_REFRESH_INTERVAL_MS). Is it possible to generate an exact 15kHz clock pulse using an Arduino? Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.         Angular; Security; Securing a Single Page Application is a very important part of its implementation, yet sometimes it brings a lot of confusion, especially when there are many ways to achieve it. Natürlich würde ich den Aufruf in eine refresh -Methode einschließen und ihn von der Datenquelleninstanz mit der Komponente und anderen geeigneten Techniken abrufen. A plan B for Bootstrap Lovers. updateTask (task: Task, id)/*: Observable */{ I have asked several questions in StackOverflow like for example: I have a navigation menu, with a list of tasks links, all of that comes from a web service. Info. Stores are otherwise just good ol’ Angular service classes. initializeTasks(){ To learn more, see our tips on writing great answers. Remember to add comments if you want, and to see How I delete and element, and if you are watching that elemnt it will send you to the /home page, click here, Is basic for any development team to know how to work in different environments, without it, is completely impossible to organize your wo. Create a New Application and Setup Angular Material. Therefor i would seperate the logic for retrieving the token from the refreshing. Milestone leveling for a party of players who drop in and out? const subject = new BehaviorSubject(0); //0 is the initial value. Let's create 3 Components that will communicate the data with each other components using the following NPM command, ng g c Component1 ; ng g c Component2 ; ng g c Component3 ; Step 3 . A BehaviorSubject emits its last emitted value to new/late subscribers ; It has an initial value; Its current value can be accessed via the getValue method; A new value can be emitted using the next method; A BehaviorSubject is multicast: Internally it holds a list of all subscribers. My application is a board game. with any other private api, it can change with an upgrade with no notice. Shopping. I personally omit the else part, when the if part clearly returns out of the method (return). In our service we will be using a special type of an Observable called a BehaviorSubject. After the update of a task, the content change, but,  it is not reflected in the menu.     .subscribe(Tasks => this.tasks = Tasks); Three ways to refresh token with Angular Http Interceptor - alexzuza/angular-refresh-token When the BehaviorSubject emits a new value then the exact … Code Review Stack Exchange is a question and answer site for peer programmer code reviews. And this is the getTask() function from the menu: ngOnInit() { In the connect method you should already be using Observable.merge to subscribe to an array of observables that include the, sort.sortChange, etc. I'm sure that there are a better approach to the same solution, but for practical purpose the app is doing what it have to do . Best way to do this is by adding an additional observable to your Datasource implementation. Per example, the AsynPipe has clear documentation that it automatically subscribe/unsubscribe for you. Previously (because it wasn't. When a file gets bigger, then i evaluate the "complexity" of the code and if its not VERY simple (i accept a 400 row switch statement as simple), i try to split it. set - Set a new value for a single property. Create the data which we want to share with all the components private logoutStatus = new BehaviorSubject (false); //3. I'll accept this answer and likely add a reply later attempting to apply the suggestions from you that I can! this.taskService.updateTask(task, id) If the token is expired and not yet requested, the process is quite straight: If the token is expired but already requested. It's hard for me to grasp to the point I need comments to make it easier.     this.taskService.getTasks() If you just want to get the data and assign it to some attribute, you should subscribe to it but cannot define your return type as Observable. The content of this field is kept private and will not be shown publicly. Ich denke, dass das MatTableDataSource Objekt in irgendeiner Weise mit dem MatTableDataSource verknüpft ist, das Sie an den MatTableDataSource Konstruktor übergeben. In this case, the blocks are a bit longer because of the pipe and the switchMap, but the return is on the first line after the if statement, so the approach is still okay for me. ng new BehaviorSubjectDemo --routing.         ); How can I use Mathematica to solve a complex truth-teller/liar logic problem? Other versions available: Angular: Angular 9, 8, 6 React: React Vue: Vue.js AngularJS: AngularJS ASP.NET Core: Blazor WebAssembly This is an example of how to setup a simple login page using Angular 10 and Basic HTTP authentication.         return this.http.get(url) This is helping (and teaching) me tons! getTasks(): void {    }.     . import { BehaviorSubject } from 'rxjs/BehaviorSubject'; Declate the task object, as a BehaviorSubject, private tasks = new BehaviorSubject([]); private taskList: Task[]; Then, depending on the context, trigger the sources.           .subscribe(); updateTask (task: Task, id): Observable{ By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. How would you gracefully handle this snippet to allow for spaces in directories?       const url = `${this.mainUrl}/node/${id}`;                 .pipe( Why do jet engine igniters require huge voltages? Join the community of millions of developers who build compelling user interfaces with Angular. Before we start, we have to setup Angular environment.         site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. refresh pending). Lines and paragraphs break automatically. To implement a fix, all we need to do is update the AppComponent: src/app/app.component.ts My current best theory is something else is interfering. If it is and the Access Token is expired, refresh the Access Token first, then send the call to the API. What determines who gets to stay in the Presidential Townhouse / Trowbridge House? I would move both services near each other, but still keep them in seperate files. There is where be BehaviorSubject's comes; Import it in the task.service.ts. To get started, we bring up a new Ionic app and add two pages and a service for our JWT refresh token flow. Yes, if none is mentioned it's public by default. Create a new Angular project using the following NPM command: ng new subjectExample; Step 2 . Reactive Angular with RXJS - Auto Refresh via Subject. And all are kind of valid :-) I am relatively new to Angular Development and rxjs in particular, so there are a lot of concepts I am likely not yet familiar with or can't apply properly.           this.initializeTasks(); This seems to be the exact same purpose of an Observable..       return this.tasks.asObservable();          const url = `${this.mainUrl}/tasks`; getTasks(): Observable { It means that a subject can emit data, on top of having the capability to be subscribed to. In Angular we use RxJS a polyfill/util library for the proposed Observables primitive in the next new version JavaScript. Be aware that there may be multiple instances of your interceptor if you import HTTPCLientModule multiple times (see HTTPInterceptor documentation). It has logic.service.ts which contains players info and state of the game. First, we need to create a new Angular application by running the following command line: ng new angular-datatable A simple GET Method. It is common in Ionic applications (and Angular applications more broadly) to create some kind of service to handle loading data from some source. I'm importing the HTTPClientModule in root, but it's a valid point ! But the reader does not know if its public by intention or if the developer has missed the private modifier. And it still failed to update the UI, so it's not the HTTP call that is the issue (which does use Angular's Http).         return this.http.get(url) For learning purpose, take a look at ", Angular10 RxJS - Interceptor to add/refresh JWT Token,, Podcast 305: What does it mean to be a “senior” software engineer, FormArray total of each formgroup via RxJS, The sum of two well-ordered subsets is well-ordered.         tap(_ => this.log(`updated task id=${id}`)), I'm looking into Angular RxJs patterns and I don't understand the difference between a BehaviorSubject and an Observable.. From my understanding, a BehaviorSubject is a value that can change over time (can be subscribed to and subscribers can receive updated results). When would you use an Observable vs a BehaviorSubject? It only takes a minute to sign up. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This article is going to focus on a specific kind of observable called Subject. The main objective of the BehaviorSubject, in this case, is that every subscriber will always get the initial or the last value that the subject emits. With "clearly" I mean that when I read the if that I already see the return, that means the if block may only be 1-3 lines long. Share.         {{task.title}} Oh also, is it syntactically possible to not have the switchmap end on "return next handle" but instead just add the token to the request and be done in the switchmap at that point?     }. Let's see some code: This is the HTML from the menu to print the tasks:
  •         ); And, from the side of the view task component, we have a form that sends the data to the updateTask()  to the task.service with the save() function. Send a variable that I get from one component to another. Instead, we used the ideas from Redux to create a state management solution that leverages Angular’s (and RxJS’s) ... Its only role is to provide a simple API to update state object and to subscribe to its updates. Allowed HTML tags: