Angular query parameters are treated as boolean types, not strings

Question

Angular query parameters are treated as boolean types, not strings

I have a situation where I need to pass a query parameter to an *ngIf, but it keeps evaluating as true because it's in string format. How can I convert the query parameter to a boolean so that it evaluates as false?

The current query param is ?paywall=true and even when using ?paywall=false, it still evaluates as true.

In my component.ts file:

ngOnInit() {
    this.paywallQuery$ = this.route.queryParamMap.pipe(map(params => params.get('paywall')));
}

And in my component.html file:

<div *ngIf="(paywallQuery$ | async)"> <-- always evaluating as true
</div>

angular typescript rxjs

Answer 1

Answer №1

Convert the value to a boolean by checking if it matches the string 'true'.

ngOnInit() {
  this.paywallQuery$ = this.route.queryParamMap.pipe(
    map(params => {
      const value = params.get('paywall');
      return value ? value.toLocaleLowerCase() === 'true' : false;
    })
  );
}

Answer 2

Convert the value to a boolean by checking if it matches the string 'true'.

ngOnInit() {
  this.paywallQuery$ = this.route.queryParamMap.pipe(
    map(params => {
      const value = params.get('paywall');
      return value ? value.toLocaleLowerCase() === 'true' : false;
    })
  );
}

Answer 3

Answer №2

If I am already relying on Angular's CDK, I would utilize the boolean coercion function called coerceBooleanProperty to convert a string into a proper boolean value.

When working with urls and attributes in the web component realm compared to using JavaScript for binding, things can be quite basic. queryparams, pathparams, and attributes are all initially stored as strings, so it is essential to properly convert them for coherent implementation.

This snippet demonstrates how I handle this situation within my code:

import { coerceBooleanProperty } from '@angular/cdk/coercion';
this.paywallQuery = coerceBooleanProperty(this.route.snapshot.paramMap.get('paywall'))

To explore additional examples, take a look at the link below: https://github.com/angular/components/blob/master/src/cdk/coercion/boolean-property.spec.ts

Answer 4

If I am already relying on Angular's CDK, I would utilize the boolean coercion function called coerceBooleanProperty to convert a string into a proper boolean value.

When working with urls and attributes in the web component realm compared to using JavaScript for binding, things can be quite basic. queryparams, pathparams, and attributes are all initially stored as strings, so it is essential to properly convert them for coherent implementation.

This snippet demonstrates how I handle this situation within my code:

import { coerceBooleanProperty } from '@angular/cdk/coercion';
this.paywallQuery = coerceBooleanProperty(this.route.snapshot.paramMap.get('paywall'))

To explore additional examples, take a look at the link below: https://github.com/angular/components/blob/master/src/cdk/coercion/boolean-property.spec.ts

Answer 5

Answer №3

To extract the parameters, you can utilize JSON.parse to parse them. When dealing with a boolean string value, it will be converted into an actual boolean.

Below is the complete code snippet:

export class Page implements OnInit {
  public paywallQuery: boolean;

  constructor(private activatedRoute: ActivatedRoute) {}

  public ngOnInit() {
    this.paywallQuery = this.extractPayWallValueFromQueryParams();
  }

  private extractQueryParams() {
    return this.activatedRoute.snapshot.params;
  }

  private extractPayWallValueFromQueryParams(): boolean {
    return JSON.parse(this.extractQueryParams().paywall);
  }
}

Please note that I have utilized the snapshot method instead of the observable query params, which is why:

<div *ngIf="paywallQuery"></div>

Answer 6

To extract the parameters, you can utilize JSON.parse to parse them. When dealing with a boolean string value, it will be converted into an actual boolean.

Below is the complete code snippet:

export class Page implements OnInit {
  public paywallQuery: boolean;

  constructor(private activatedRoute: ActivatedRoute) {}

  public ngOnInit() {
    this.paywallQuery = this.extractPayWallValueFromQueryParams();
  }

  private extractQueryParams() {
    return this.activatedRoute.snapshot.params;
  }

  private extractPayWallValueFromQueryParams(): boolean {
    return JSON.parse(this.extractQueryParams().paywall);
  }
}

Please note that I have utilized the snapshot method instead of the observable query params, which is why:

<div *ngIf="paywallQuery"></div>

Angular query parameters are treated as boolean types, not strings

Answer №1

Answer №2

Answer №3

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