How to ensure Service is loaded before App Component in Angular 6?

Question

How to ensure Service is loaded before App Component in Angular 6?

My Data service is responsible for fetching the JSON Object value, however all components load before the data service finishes loading. This results in undefined values when I call the service method from components.

angular typescript

Answer 1

Answer №1

Assuming you are utilizing a Router to access your page, you can easily utilize the "resolver" feature by using RouterLink description.

path: 'app', component: AppPage, resolve: { myData : DataResolve }

Here, we request for the resolution of the variable "myData" through the resolver DataResolve. DataResolve is a straightforward Injectable that implements the Resolve interface:

import { Resolve } from '@angular/router';
import { Injectable } from '@angular/core';

@Injectable()
export class UserResolve implements Resolve<any> {

  constructor(private myService: MyService) {}

  async resolve() {
    const myData = await this.myService.getMyData().toPromise();
    return myData;
  }

}

Once the values are resolved, the component will load. You can then retrieve your data from the ActivatedRoute:

 import { ActivatedRoute } from '@angular/router';

 constructor(private route: ActivatedRoute {
    this.route.data.subscribe(() => {
      this.data = this.route.snapshot.data.myData;
    });
  }

Answer 2

Assuming you are utilizing a Router to access your page, you can easily utilize the "resolver" feature by using RouterLink description.

path: 'app', component: AppPage, resolve: { myData : DataResolve }

Here, we request for the resolution of the variable "myData" through the resolver DataResolve. DataResolve is a straightforward Injectable that implements the Resolve interface:

import { Resolve } from '@angular/router';
import { Injectable } from '@angular/core';

@Injectable()
export class UserResolve implements Resolve<any> {

  constructor(private myService: MyService) {}

  async resolve() {
    const myData = await this.myService.getMyData().toPromise();
    return myData;
  }

}

Once the values are resolved, the component will load. You can then retrieve your data from the ActivatedRoute:

 import { ActivatedRoute } from '@angular/router';

 constructor(private route: ActivatedRoute {
    this.route.data.subscribe(() => {
      this.data = this.route.snapshot.data.myData;
    });
  }

Answer 3

Answer №2

If you want to fetch data, consider using a resolver within your data service:

Include the resolve property in your route.
Create a method that implements the resolve interface in your service.
Then, simply subscribe to the observable service in your component.

For more information, check out the angular.io documentation on resolvers.

Answer 4

If you want to fetch data, consider using a resolver within your data service:

Include the resolve property in your route.
Create a method that implements the resolve interface in your service.
Then, simply subscribe to the observable service in your component.

For more information, check out the angular.io documentation on resolvers.

Answer 5

Answer №3

If you want to handle resolving in your router, check out the following resources:

Explore more through this link below:

For additional information on resolving in Angular routers, visit:

https://angular.io/api/router/Resolve

Answer 6

If you want to handle resolving in your router, check out the following resources:

Explore more through this link below:

For additional information on resolving in Angular routers, visit:

https://angular.io/api/router/Resolve

Answer 7

Answer №4

When utilizing HttpClient to fetch data, it is necessary to subscribe to the stream since it returns an observable.

this.MyService.method().subscribe(value => {
  // You can access the value here
});

Alternatively, you can use the async pipe in the template.

// Controller
value$ = this.MyService.method()

// Template
<p>{{value$ | async}}</p>

In addition, you have the option to register your service factory into Angular providers using the APP_INITIALIZER token, and your function will be executed upon application initialization.

@NgModule({
  ...
  providers: [
    { provide: APP_INITIALIZER, useFactory: initSomething, multi: true }
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

Answer 8

When utilizing HttpClient to fetch data, it is necessary to subscribe to the stream since it returns an observable.

this.MyService.method().subscribe(value => {
  // You can access the value here
});

Alternatively, you can use the async pipe in the template.

// Controller
value$ = this.MyService.method()

// Template
<p>{{value$ | async}}</p>

In addition, you have the option to register your service factory into Angular providers using the APP_INITIALIZER token, and your function will be executed upon application initialization.

@NgModule({
  ...
  providers: [
    { provide: APP_INITIALIZER, useFactory: initSomething, multi: true }
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

Answer 9

Answer №5

One way to ensure your service loads before any other component is by including it as a parameter in the AppComponent constructor of your Angular application

export class AppComponent {
      constructor(private myService: MyService) {}
...
}

If you need to make any initial calls when the service is constructed, that should be handled within its own constructor function

Answer 10

One way to ensure your service loads before any other component is by including it as a parameter in the AppComponent constructor of your Angular application

export class AppComponent {
      constructor(private myService: MyService) {}
...
}

If you need to make any initial calls when the service is constructed, that should be handled within its own constructor function

How to ensure Service is loaded before App Component in Angular 6?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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