Angular 中文文档

Angular ng-select - Lightweight all in one UI Select, Multiselect and Autocomplete


See Demo page.

Versions


Angular ng-select
:--- :---
>=15.0.0 <16.0.0 v10.x
>=14.0.0 <15.0.0 v9.x
>=13.0.0 <14.0.0 v8.x
>=12.0.0 <13.0.0 v7.x
>=11.0.0 <12.0.0 v6.x
>=10.0.0 <11.0.0 v5.x
>=9.0.0 <10.0.0 v4.x
>=8.0.0 <9.0.0 v3.x
>=6.0.0 <8.0.0 v2.x
v5.x.x v1.x

Table of contents


Features
Getting started
API
Change detection
Custom styles
Validation state

Contributing
Development
Inspiration

Features


Custom binding to property or object
Custom option, label, header and footer templates
Virtual Scroll support with large data sets (>5000 items).
Infinite scroll
Keyboard navigation
Multiselect
Flexible autocomplete with client/server filtering
Custom search
Custom tags
Append to
Group items
Output events
Accessibility
Good base functionality test coverage
Themes

Warning


Library is under active development and may have API breaking changes for subsequent major versions after 1.0.0.

Getting started


Step 1: Install ng-select:


NPM


  1. ``` shell
  2. npm install --save @ng-select/ng-select
  3. ```

YARN


  1. ``` shell
  2. yarn add @ng-select/ng-select
  3. ```

Step 2: Import the NgSelectModule and angular FormsModule module:


  1. ``` js
  2. import { NgSelectModule } from '@ng-select/ng-select';
  3. import { FormsModule } from '@angular/forms';

  5. @NgModule({
  6.   declarations: [AppComponent],
  7.   imports: [NgSelectModule, FormsModule],
  8.   bootstrap: [AppComponent]
  9. })
  10. export class AppModule {}
  11. ```

Step 3: Include a theme:


To allow customization and theming, ng-select bundle includes only generic styles that are necessary for correct layout and positioning. To get full look of the control, include one of the themes in your application. If you're using the Angular CLI, you can add this to your styles.scss or include it in .angular-cli.json (Angular v5 and below) or angular.json (Angular v6 onwards).

  1. ``` scss
  2. @import "~@ng-select/ng-select/themes/default.theme.css";
  3. // ... or
  4. @import "~@ng-select/ng-select/themes/material.theme.css";

  6. ```

Step 4 (Optional): Configuration


You can also set global configuration and localization messages by injecting NgSelectConfig service, typically in your root component, and customize the values of its properties in order to provide default values.

  1. ``` js
  2.   constructor(private config: NgSelectConfig) {
  3.       this.config.notFoundText = 'Custom not found';
  4.       this.config.appendTo = 'body';
  5.       // set the bindValue to global config when you use the same
  6.       // bindValue in most of the place.
  7.       // You can also override bindValue for the specified template
  8.       // by defining `bindValue` as property
  9.       // Eg :
  10.       this.config.bindValue = 'value';
  11.   }
  12. ```

Usage


Define options in your consuming component:

  1. ``` js
  2. @Component({...})
  3. export class ExampleComponent {

  5.     selectedCar: number;

  7.     cars = [
  8.         { id: 1, name: 'Volvo' },
  9.         { id: 2, name: 'Saab' },
  10.         { id: 3, name: 'Opel' },
  11.         { id: 4, name: 'Audi' },
  12.     ];
  13. }
  14. ```

In template use ng-select component with your options

  1. ``` html
  2. !--Using ng-option and for loop-->
  3. <ng-select [(ngModel)]="selectedCar">
  4.    <ng-option *ngFor="let car of cars" [value]="car.id">{{car.name}}</ng-option>
  5. </ng-select>
  7. !--Using items input-->
  8. <ng-select [items]="cars" 
  9.            bindLabel="name" 
  10.            bindValue="id" 
  11.            [(ngModel)]="selectedCar">
  12. </ng-select>
  13. ```

For more detailed examples see Demo page

SystemJS


If you are using SystemJS, you should also adjust your configuration to point to the UMD bundle.

In your systemjs config file, map needs to tell the System loader where to look for ng-select :

  1. ``` js
  2. map: {
  3.   '@ng-select/ng-select': 'node_modules/@ng-select/ng-select/bundles/ng-select.umd.js',
  4. }
  5. ```

API


Inputs


Input Type Default Required Description
:--- :--- :--- :--- :---
[addTag] `boolean ((term: string) => any Promise<any>)` false
addTagText string Add item no Set custom text when using tagging
appearance string underline no Allows to select dropdown appearance. Set to outline to add border instead of underline (applies only to Material theme)
appendTo string null no Append dropdown to body or any other element using css selector. For correct positioning body should have position:relative
bindValue string - no Object property to use for selected model. By default binds to whole object.
bindLabel string label no Object property to use for label. Default label
[closeOnSelect] boolean true no Whether to close the menu when a value is selected
clearAllText string Clear all no Set custom text for clear all icon title
[clearable] boolean true no Allow to clear selected value. Default true
[clearOnBackspace] boolean true no Clear selected values one by one when clicking backspace. Default true
[compareWith] (a: any, b: any) => boolean (a, b) => a === b no A function to compare the option values with the selected values. The first argument is a value from an option. The second is a value from the selection(model). A boolean should be returned.
dropdownPosition bottom top auto auto
[groupBy] string Function null no
[groupValue] (groupKey: string, children: any[]) => Object - no Function expression to provide group value
[selectableGroup] boolean false no Allow to select group when groupBy is used
[selectableGroupAsModel] boolean true no Indicates whether to select all children or group itself
[items] Array<any> [] yes Items array
[loading] boolean - no You can set the loading state from the outside (e.g. async items loading)
loadingText string Loading... no Set custom text when for loading items
labelForId string - no Id to associate control with label.
[markFirst] boolean true no Marks first item as focused when opening/filtering.
[isOpen] boolean - no Allows manual control of dropdown opening and closing. True - won't close. False - won't open.
maxSelectedItems number none no When multiple = true, allows to set a limit number of selection.
[hideSelected] boolean false no Allows to hide selected items.
[multiple] boolean false no Allows to select multiple items.
notFoundText string No items found no Set custom text when filter returns empty result
placeholder string - no Placeholder text.
[searchable] boolean true no Allow to search for value. Default true
[readonly] boolean false no Set ng-select as readonly. Mostly used with reactive forms.
[searchFn] (term: string, item: any) => boolean null no Allow to filter by custom search function
[searchWhileComposing] boolean true no Whether items should be filtered while composition started
[trackByFn] (item: any) => any null no Provide custom trackBy function
[clearSearchOnAdd] boolean true no Clears search input when item is selected. Default true. Default false when closeOnSelect is false
[editableSearchTerm] boolean false no Allow to edit search query if option selected. Default false. Works only if multiple is false.
[selectOnTab] boolean false no Select marked dropdown item using tab. Default false
[openOnEnter] boolean true no Open dropdown using enter. Default true
[typeahead] Subject - no Custom autocomplete or advanced filter.
[minTermLength] number 0 no Minimum term length to start a search. Should be used with typeahead
typeToSearchText string Type to search no Set custom text when using Typeahead
[virtualScroll] boolean false no Enable virtual scroll for better performance when rendering a lot of data
[inputAttrs] { [key: string]: string } - no Pass custom attributes to underlying input element
[tabIndex] number - no Set tabindex on ng-select
[keyDownFn] ($event: KeyboardEvent) => bool true no Provide custom keyDown function. Executed before default handler. Return false to suppress execution of default key down handlers

Outputs


Output Description
:--- :---
(add) Fired when item is added while [multiple]="true". Outputs added item
(blur) Fired on select blur
(change) Fired on model change. Outputs whole model
(close) Fired on select dropdown close
(clear) Fired on clear icon click
(focus) Fired on select focus
(search) Fired while typing search term. Outputs search term with filtered items
(open) Fired on select dropdown open
(remove) Fired when item is removed while [multiple]="true"
(scroll) Fired when scrolled. Provides the start and end index of the currently available items. Can be used for loading more items in chunks before the user has scrolled all the way to the bottom of the list.
(scrollToEnd) Fired when scrolled to the end of items. Can be used for loading more items in chunks.

Methods


Name Description
:--- :---
open Opens the select dropdown panel
close Closes the select dropdown panel
focus Focuses the select element
blur Blurs the select element

Other


Name Type Description
:--- :--- :---
[ngOptionHighlight] directive Highlights search term in option. Accepts search term. Should be used on option element. README
NgSelectConfig configuration Configuration provider for the NgSelect component. You can inject this service and provide application wide configuration.
SELECTION_MODEL_FACTORY service DI token for SelectionModel implementation. You can provide custom implementation changing selection behaviour.

Custom selection logic


Ng-select allows to provide custom selection implementation using SELECTION_MODEL_FACTORY. To override default logic provide your factory method in your angular module.

  1. ``` js
  2. // app.module.ts
  3. providers: [
  4.     { provide: SELECTION_MODEL_FACTORY, useValue: <SelectionModelFactory>CustomSelectionFactory }
  5. ]

  7. // selection-model.ts
  8. export function CustomSelectionFactory() {
  9.     return new CustomSelectionModel();
  10. }

  12. export class CustomSelectionModel implements SelectionModel {
  13.     ...
  14. }
  15. ```

Change Detection


Ng-select component implements OnPush change detection which means the dirty checking checks for immutable data types. That means if you do object mutations like:

  1. ``` js
  2. this.items.push({id: 1, name: 'New item'})
  3. ```

Component will not detect a change. Instead you need to do:

  1. ``` js
  2. this.items = [...this.items, {id: 1, name: 'New item'}];
  3. ```

This will cause the component to detect the change and update. Some might have concerns that this is a pricey operation, however, it is much more performant than running ngDoCheck and constantly diffing the array.

Custom styles


If you are not happy with default styles you can easily override them with increased selector specificity or creating your own theme. This applies if you are using no ViewEncapsulation or adding styles to global stylesheet. E.g.

  1. ``` html
  2. <ng-select class="custom"></ng-select>
  3. ```

  1. ``` css
  2. .ng-select.custom {
  3.     border:0px;
  4.     min-height: 0px;
  5.     border-radius: 0;
  6. }
  7. .ng-select.custom .ng-select-container  {            
  8.     min-height: 0px;
  9.     border-radius: 0;
  10. }
  11. ```

If you are using ViewEncapsulation, you could use special ::ng-deep selector which will prevent scoping for nested selectors altough this is more of a workaround and we recommend using solution described above.

  1. ``` css
  2. .ng-select.custom ::ng-deep .ng-select-container  {            
  3.     min-height: 0px;
  4.     border-radius: 0;
  5. }
  6. ```

WARNING: Keep in mind that ng-deep is deprecated and there is no alternative to it yet. See Here.

Validation state


By default when you use reactive forms validators or template driven forms validators css class ng-invalid will be applied on ng-select. You can show errors state by adding custom css style

  1. ``` css
  2. ng-select.ng-invalid.ng-touched .ng-select-container {
  3.     border-color: #dc3545;
  4.     box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 0 3px #fde6e8;
  5. }
  6. ```

Contributing


Contributions are welcome. You can start by looking at issues with label Help wantedor creating new Issue with proposal or bug report. Note that we are using https://conventionalcommits.org/ commits format.

Development


Perform the clone-to-launchsteps with these terminal commands.

Run demo page in watch mode


  1. ``` sh
  2. git clone https://github.com/ng-select/ng-select
  3. cd ng-select
  4. yarn
  5. yarn run start

  7. ```

Testing


  1. ``` sh
  2. yarn run test
  3. or
  4. yarn run test:watch

  6. ```

Release


To release to npm just run ./release.sh, of course if you have permissions ;)

Inspiration


This component is inspired by React select and Virtual scroll. Check theirs amazing work and components :)