Exploring the usage of Booleans within an Angular component

Question

Exploring the usage of Booleans within an Angular component

Recently, I decided to delve into Angular and experiment with some hands-on projects. One of the challenges I encountered was utilizing the same component for both editing and creating a product. To address this, I implemented an if statement within the component to differentiate between the two actions. However, I noticed that the code inside the if statement wasn't being executed when the request URL was

http://localhost:4200/product/Edit/Redmond?edit=true

. Although I had included code to manage the route parameters (which I omitted for conciseness), I couldn't determine what exactly was missing from my implementation.

export class ProductEditComponent implements OnInit {
isEdit= false;
uiProduct:ProductModel;
ngOnInit() {
this.activatedRoute.queryParams.subscribe(queryParams=>{
  this.isEdit=queryParams['edit']      
  console.log(this.isEdit); // it's true here for the Edit Route
})
if (this.isEdit ==true) {      
  this.productService.
    GetProductByName(this.name)
    .subscribe((response: ProductModel) => {
      this.uiProduct = response;          
    });
}
}

angular typescript

Answer 1

Answer №1

When using this.activatedRoute.queryParams.subscribe

, keep in mind that it is asynchronous. Therefore, your isEdit variable will only receive a value after you have checked it. Consider moving the check inside the subscribe method or using await with the subscribe call.

Answer 2

When using this.activatedRoute.queryParams.subscribe

, keep in mind that it is asynchronous. Therefore, your isEdit variable will only receive a value after you have checked it. Consider moving the check inside the subscribe method or using await with the subscribe call.

Answer 3

Answer №2

After asynchronously assigning the isEdit variable, consider using RxJS higher order mapping operators (such as switchMap) for interdependent observables. You can also use the filter operator to emit only when the edit parameter is true.

Here's an example:

export class ProductEditComponent implements OnInit {
  uiProduct: ProductModel;

  ngOnInit() {
    this.activatedRoute.queryParams.pipe(
      filter((queryParams: any) => (!!queryParams['edit'])), // <-- proceed only if `edit` is true
      switchMap(_ => this.productService.GetProductByName(this.name))
    ).subscribe({
      next: (response: ProductModel) => {
        this.uiProduct = response;
      },
      error: (error: any) => {
        // handle error
      }
    });
  }
}

Update: Incorporate async query param elsewhere

To maintain the asynchronous nature of data and reuse it in other parts of your code, consider using RxJS ReplaySubject with a buffer of 1. Remember to close all open subscriptions when the component is destroyed, which can be achieved using takeUntil.

import { ReplaySubject, Subject } from 'rxjs';
import { tap, filter, switchMap, takeUntil } from 'rxjs/operators;

export class ProductEditComponent implements OnInit, OnDestroy {
  uiProduct: ProductModel;
  editSrc = new ReplaySubject<any>(1);
  edit$ = this.editSrc.asObservable();
  closed$ = new Subject<any>();

  // Implementation continues...

Answer 4

After asynchronously assigning the isEdit variable, consider using RxJS higher order mapping operators (such as switchMap) for interdependent observables. You can also use the filter operator to emit only when the edit parameter is true.

Here's an example:

export class ProductEditComponent implements OnInit {
  uiProduct: ProductModel;

  ngOnInit() {
    this.activatedRoute.queryParams.pipe(
      filter((queryParams: any) => (!!queryParams['edit'])), // <-- proceed only if `edit` is true
      switchMap(_ => this.productService.GetProductByName(this.name))
    ).subscribe({
      next: (response: ProductModel) => {
        this.uiProduct = response;
      },
      error: (error: any) => {
        // handle error
      }
    });
  }
}

Update: Incorporate async query param elsewhere

To maintain the asynchronous nature of data and reuse it in other parts of your code, consider using RxJS ReplaySubject with a buffer of 1. Remember to close all open subscriptions when the component is destroyed, which can be achieved using takeUntil.

import { ReplaySubject, Subject } from 'rxjs';
import { tap, filter, switchMap, takeUntil } from 'rxjs/operators;

export class ProductEditComponent implements OnInit, OnDestroy {
  uiProduct: ProductModel;
  editSrc = new ReplaySubject<any>(1);
  edit$ = this.editSrc.asObservable();
  closed$ = new Subject<any>();

  // Implementation continues...

Answer 5

Answer №3

One of my favorite techniques is creating 2 separate routers for the same component:

 const routes: Routes = [
      { path: 'edit/:id', component: RequestReportComponent },
      { path: 'add', component: RequestReportComponent },
     ];

Within the component, I implement a check like this:

isEditMode:boolean;
  constructor(private route: ActivatedRoute) {
             this.isEditMode = this.route.snapshot.params.id;
   
  }

Answer 6

One of my favorite techniques is creating 2 separate routers for the same component:

 const routes: Routes = [
      { path: 'edit/:id', component: RequestReportComponent },
      { path: 'add', component: RequestReportComponent },
     ];

Within the component, I implement a check like this:

isEditMode:boolean;
  constructor(private route: ActivatedRoute) {
             this.isEditMode = this.route.snapshot.params.id;
   
  }

Exploring the usage of Booleans within an Angular component

Answer №1

Answer №2

Update: Incorporate async query param elsewhere

Answer №3

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