Breadcrumb¶

Usage¶

When to use¶

• Use breadcrumbs when the user is most likely to have landed on the page from an external source
• Use for large websites and products that have hierarchically arranged pages

When a breadcrumb may not help¶

• Don't use breadcrumbs for single-level websites that don't have a logical hierarchy or grouping.

Design¶

Elements¶

A breadcrumb consists of the following elements:

1. Root element: Highest entity level, displayed with an icon or a text.
2. Entity name: An entity represents a section or page within the product or page. Entity names use a button link that uses the section or page title to link to that section or page.
3. Separator: Provides a visual distinction between individual entities using the same font as the rest of the breadcrumb (not icons).
4. Current page or content: Indicates the current position. It's not a link.

Root element¶

The root element can either be the default icon element-breadcrumb-root or a meaningful text, like Startpage.

Responsive behavior¶

The default rule is to show as much of the path as possible in the available real estate. Entities will be truncated if the available space is not sufficient to show the entire breadcrumb.

Truncation¶

Super long entity names are truncated.

In order to see the full entity label, the user can click on it and the full label will be shown, as a clickable menu element. Clicking somewhere on the screen will hide the menu.

Long breadcrumb¶

When a path contains more levels of entities that can be displayed, the breadcrumb auto-collapses and uses ellipses to indicate more information. It's best practice to show at least the first and last entity when collapsing. Users expand the breadcrumb by clicking on the ellipses.

Code¶

The first entry will be used as the root element and won't show the title but will be represented as an icon.

The items parameter takes an array of BreadcrumbItem entries. They contain a title and link property. The link property can be an array or a string and will be used as a routerLink.

Usage¶

import { SiBreadcrumbRouterComponent } from '@siemens/element-ng/breadcrumb';

@Component({
  imports: [SiBreadcrumbRouterComponent,...]
})

Breadcrumb Router¶

The si-breadcrumb-router component displays a breadcrumb according to the Angular router hierarchy of the current route. The breadcrumb titles and links are configurable by enriching the Angular route configuration with addition data. The component uses the default implementation SiBreadcrumbDefaultResolverService of the SiBreadcrumbResolverService interface, which reads the router configuration and provides the BreadcrumbItem objects. Using the injector token SI_BREADCRUMB_RESOLVER_SERVICE you can provide your own SiBreadcrumbResolverService implementation.

import { SI_BREADCRUMB_RESOLVER_SERVICE, SiBreadcrumbRouterComponent } from '@siemens/element-ng/breadcrumb-router';

...

@Component({
  imports: [
    ...
    SiBreadcrumbRouterComponent,
  ],
  providers: [
    {
      provide: SI_BREADCRUMB_RESOLVER_SERVICE,
      useClass: YourBreadcrumbResolverService,
    }
  ]
  ...
})

When using the default resolver service you need to enrich the Angular route configuration with breadcrumb information. The default resolver iterates through the route hierarchy to construct the breadcrumb items. The breadcrumb item title is taken from the path element or from a title property of the data configuration object. For a custom configuration that deviate from the route hierarchy, use a siBreadcrumb object in the data object that provides the complete breadcrumb item information for that route. Configure title and an optional link. The following example shows the variations:

• title configuration in data object
• title with route parameter configuration in data object
• title and link configuration in nested siBreadcrumb object

The title can also be a translation key and gets translated. Unfortunately, translation does currently not work in combination with route parameter.

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

export const routes: Route[] = [
  {
    path: 'test',
    data: {
      title: 'Test' // Title is displayed in the breadcrumb
    },
    children: [
      {
        path: ':id',
        data: {
          title: 'Test - {id}' // id will be resolved with the current parameter value
        }
      }
    ]
  },
  {
    path: 'test/sub-test',
    data: {
      /*
      * In this scenario the automatic calculation of the route is broken because
      * test/sub-test is handled as one UrlSegment. Therefore, only one breadcrumb
      * link would be rendered. Providing the links manually solves this problem.
      * It is not possible to define wildcards in the link names here.
      */
      siBreadcrumb: [
        { title: 'Test', link: '/test' },
        { title: 'Sub-Test', link: '/test/sub-test' }
      ]
    }
  },
  {
    path: 'protocol/:idprotocol/run/:idrun',
    component: RunComponent,
    data: {
      siBreadcrumb: [
        { title: 'Protocol ({idprotocol})', link: 'protocol/:idprotocol' },
        { title: 'Run ({idrun})' } // current route is used if no path is provided
      ]
    }
  }
];

The siBreadcrumb object is an array of BreadcrumbRouterLink objects.

See Angular docs to learn how to resolve route data with the Angular router resolvers.

Custom Breadcrumb Resolver¶

There are scenarios where the default resolver is not sufficient. In those cases you can write a custom resolver like this:

import { Injectable } from '@angular/core';
import { ActivatedRouteSnapshot } from '@angular/router';
import { BreadcrumbItem } from '@siemens/element-ng/breadcrumb';
import { SiBreadcrumbDefaultResolverService } from '@siemens/element-ng/breadcrumb-router';
import { Observable } from 'rxjs';

@Injectable()
export class CustomBreadcrumbResolverService extends SiBreadcrumbDefaultResolverService {

  resolve(route: ActivatedRouteSnapshot): BreadcrumbItem[] | Observable<BreadcrumbItem[]> {
    return super.resolve(route)
      .map((link: BreadcrumbItem) => ({ ...link, title: rewriteName(link.name) }));
  }

}

The resolver uses the following type:

Afterwards you need to provide the custom resolver, instead of the default resolver, in your app.module.ts:

import { SI_BREADCRUMB_RESOLVER_SERVICE, SiBreadcrumbRouterComponent } from '@siemens/element-ng/breadcrumb-router';

...

@Component({
  imports: [
    ...
    SiBreadcrumbRouterComponent,
  ],
  providers: [
    {
      provide: SI_BREADCRUMB_RESOLVER_SERVICE,
      useClass: CustomBreadcrumbResolverService,
    }
  ]
  ...
})

export class AppComponent {
}