In angular 13, how can I get all API data before rendering the page?

In Angular 13, one way to get all API data before rendering the page is to use the Resolve interface and the resolve property of the Route object. This allows you to specify a service the router will call before the route is activated. The router will wait for the service to complete before rendering the associated component.

Here is an example of how you might use the Resolve interface and the resolve property to accomplish this:

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

@Injectable({
  providedIn: 'root'
})
export class ApiDataResolver implements Resolve<any> {
  resolve(): Observable<any> {
    // Return an Observable that represents the API request(s) you want to
    // execute before the route is activated.
  }
}

This is a service that implements the Resolve interface, which requires that it have a resolve Method. This method should return an Observable that represents the API request(s) you want to execute before the route is activated.

To use this service, you would register it with a route using the resolve property of the Route object:

{
  path: 'my-route',
  component: MyComponent,
  resolve: {
    data: ApiDataResolver
  }
}

In this example, the ApiDataResolver the router will call service before the MyComponent is activated. The router will wait for the Observable returned by the resolve method to complete before rendering the MyComponent.

Once the MyComponent is activated, the data returned by the ApiDataResolver service will be available in the component through the ActivatedRoute service, using the data property:

import { ActivatedRoute } from '@angular/router';
export class MyComponent {
  constructor(private route: ActivatedRoute) {
    this.route.data.subscribe(data => {
      // The data returned by the ApiDataResolver service is available here.
    });
  }
}

This approach allows you to retrieve all the necessary data from the API before rendering the page, ensuring that the component has all the data it needs to display correctly.