Select¶

Select inputs are fields that allow users to choose options from a menu.

Usage¶

Element offers two distinct select input types: the Default Select and the Advanced Select.

The default select is based on the native HTML select element. Use it for straightforward scenarios where users need to select a single option from a dropdown list.

The advanced select is designed to accommodate more complex requirements, offering support for single-selection, multi-selection, icons, and a search function. This variant should be employed only when one or more of the mentioned capabilities are necessary.

Select input field

When to use select input fields¶

When users need to make a choice among a list of options.
When there are more than 5 options to choose from.
When options can be logically grouped (e.g., countries, cities, etc.).
Use it in forms and for atribute selection.

Best practices for select input field¶

Don't use it if there are less than three options available for selection.
Analyze what actions will save more time for the user (e.g. selecting an item versus typing that item).
If possible, mark the default option as the recommended one (avoid extra clicking).

Code¶

References¶

Bootstrap: Select

Example¶

si-select component¶

Element also offers a custom select component called si-select. The si-select component provide the following abilities:

specify the icon for each specified option.
disable options
single / multi-select behavior
custom option input
option groups
customizable rendering of options
option filtering
customizable footer with actions

The component should only be used if you require one of the listed abilities. Otherwise the native select input with Bootstrap markup is preferred.

Usage¶

si-select can be imported using the module

import { SiSelectModule } from '@siemens/element-ng/select';

@NgModule({
  imports: [SiSelectModule, ...]
})

or as a standalone component:

import {
  SiSelectComponent,
  SiSelectSimpleOptionsDirective, // At least one option directive is required. Unused option types can be omitted.
  SiSelectSingleValueDirective, // At least one value directive is required. Unused value types can be omitted.
  SiSelectMultiValueDirective
} from '@siemens/element-ng/select';

@Component({
  imports: [
    SiSelectComponent,
    SiSelectSimpleOptionsDirective,
    SiSelectSingleValueDirective,
    SiSelectMultiValueDirective,
  ]
})

Options¶

Options are provided as an array of SelectItem<T> objects:

<si-select
  [options]="[
    {
      type: 'option',
      value: { id: id, myProperty: myValue },
      label: 'Label',
      disabled: false,
      icon: 'element-face-happy',
      iconColor: 'status-success'
    }
  ]"
/>

Customize option rendering using a template:

<si-select
  [options]="[
    { type: 'option', value: 'good', label: 'Good' },
    { type: 'option', value: 'fair', label: 'Fair' },
    { type: 'option', value: 'bad', label: 'Bad' }
  ]"
>
  <ng-template let-option siSelectOptionTemplate>{{ option.label | uppercase }}</ng-template>
</si-select>

Wrap options in groups:

<si-select
  [options]="[
    {
      type: 'group',
      label: 'Group',
      options: [{ type: 'option', label: 'Option', value: 'value' }]
    }
  ]"
>
  <!-- Optional group template -->
  <ng-template let-group siSelectGroupTemplate>{{ group.label | uppercase }}</ng-template>
</si-select>

Lazy options¶

Instead of providing eagerly loaded options, applications can provide an [optionSource]. The option source allows lazy loading of options. It can be used with or without filtering.

To use the [optionSource] applications must implement the SelectOptionSource interface:

// This provides options which value are of type MyValue.
// For async methods the si-select will show a loading spinner until the observable emits the first time.
// Always return options in a consistent order.
export class MyOptionSource implements SelectOptionSource<MyValue> {

  getOptionsForValues(values: MyValue[]): Observable<SelectOptionNext<MyValue>[]> {
    // si-select will call this function when it needs to get options for the provided values.
    // This function is typically called when the value is set via a formControl or ngModel.
    // Lookup the values on your server and return the corresponding options.
  }

  getAllOptions?(): Observable<SelectItem<MyValue>[]> {
    // This function is optional, if filtering is enabled.
    // The options returned by this function are shown in the dropdown when no search value is provided.
    // You can return all available options or just a subset of the most common options.
    // If this function is not implemented only the selected options are shown.
  }

  getOptionsForSearch?(search: MyValue): Observable<SelectItem<MyValue>[]> {
    // This function is required if filtering is enabled.
    // It is never called with an empty search value.
    // Return all options that matches the search value.
  }

  compareOptions?(a: SelectOptionNext<MyValue>, b: SelectOptionNext<MyValue>): number {
    // This function is optional.
    // If provided it is used to compare options for sorting.
    // This ensures a correct order if options are loaded from the cache.
  }

  optionsEqual?(optionA: MyValue, optionB: MyValue): boolean {
    // By default si-select checks values on equality by reference.
    // If you use objects as values override this method so that equal values are recognized as such.
    // For primitiv values like strings this method should be omitted.
  }
}

Then use this source in your component:

import { SiSelectComponent, SiSelectSingleValueDirective, SiSelectLazyOptionsDirective } from '@siemens/element-ng/select';

@Component({
  selector: 'app-sample',
  template: '<si-select [optionSource]="myOptionSource" [formControl]="control" />',
  standalone: true,
  imports: [SiSelectComponent, SiSelectSingleValueDirective, SiSelectLazyOptionsDirective]
})
export class SampleComponent {
  myOptionSource = new MyOptionSource();
  control = new FormControl<MyValue | null>(null);
}

Selection¶

Single selection:

@Component({
  standalone: true,
  selector: 'app-sample',
  imports: [SiSelectComponent, SiSelectSimpleOptionsDirective, SiSelectSingleValueDirective],
  template: '<si-select [options]="optionsList" [(value)]="selected" />'
})
export class SampleComponent {
  optionsList: SelectItem<string>[] = [
    {
      type: 'option',
      value: 'good',
      label: 'Good'
    },
    {
      type: 'option',
      value: 'fair',
      label: 'Fair'
    }
  ];
  selected = 'good';
}

Multi selection:

@Component({
  standalone: true,
  selector: 'app-sample',
  imports: [SiSelectComponent, SiSelectSimpleOptionsDirective, SiSelectMultiValueDirective],
  template: '<si-select multi [options]="optionsList" [(value)]="multiValue" />'
})
export class SampleComponent {
  optionsList: SelectItem<string>[] = [
    { type: 'option', value: 'good', label: 'Good' },
    { type: 'option', value: 'fair', label: 'Fair' }
  ];
  multiValue = ['good', 'fair'];
}

Filtering options¶

Add the attribute hasFilter to enable an input element for option filtering in the overlay of the si-select component. If a custom template is used, a value provider is required.

<si-select hasFilter [options]="[...]" />

By using the siSelectActions directive, you can add custom actions to the footer of the si-select component.

To align the styling to the design system specification it is necessary that actions:

apply the siSelectAction directive to each item
and footer buttons shall apply the following classes btn btn-link.

<si-select [options]="[{ id: 'option1', title: 'Option 1' }, { id: 'option2', title: 'Option 2' }]" >
  <ng-template siSelectActions>
    <button siSelectAction type="button" class="btn btn-link" aria-label="Action 1">Action 1</button>
    <button siSelectAction type="button" class="btn btn-link" aria-label="Action 2">Action 2</button>
  </ng-template>
</si-select>

In some scenarios it is necessary to close the dropdown on click for example to display a modal dialog. The siSelectActions directive offers an input selectActionAutoClose for this purpose.

The following demonstrates how to add a "Create" button within the dropdown actions that, when clicked, will close the dropdown:

<si-select [options]="[{ id: 'option1', title: 'Option 1' }, { id: 'option2', title: 'Option 2' }]" >
  <ng-template siSelectActions>
    <button 
      siSelectAction 
      selectActionAutoClose
      type="button"
      class="btn btn-link" 
      (click)="....">
      Create
    </button>
  </ng-template>
</si-select>

Except where otherwise noted, content on this site is licensed under MIT License.

Select¶

Usage¶

When to use select input fields¶

Best practices for select input field¶

Design¶

Default select¶

Advanced select¶

States¶

Label (optional)¶

Validation states¶

Code¶

References¶

Example¶

si-select component¶

Usage¶

Options¶

Lazy options¶

Selection¶

Filtering options¶

Footer actions¶