オートコンプリートの実装 質問する

アップデート：この答えは、ng2-completerAngular2 オートコンプリート コンポーネント。以下は Angular2 の既存のオートコンプリート コンポーネントのリストです。

1. ng2 コンプリーター
2. ng2 オートコンプリート
3. ng2-typeahead

このアイデアを思いついたのは@dan-cancroさんです

独自の指令を作成したい人のために、元の回答をそのまま残します。

オートコンプリートリストを表示するには、まず属性ディレクティブ入力テキストに基づいて候補リストを返し、ドロップダウンに表示します。このディレクティブには、リストを表示するための 2 つのオプションがあります。

1. nativeElementへの参照を取得し、DOMを直接操作する
2. DynamicComponentLoader を使用してリスト コンポーネントを動的にロードする

2 番目の方法は、DOM を直接操作して Angular 2 のコア メカニズムをバイパスするのではなく、それらを使用するため、より良い選択であるように思われます。そのため、この方法を使用します。

ディレクティブコードは次のとおりです。

"use strict";
import {Directive, DynamicComponentLoader, Input, ComponentRef, Output, EventEmitter, OnInit, ViewContainerRef} from "@angular/core";
import {Promise} from "es6-promise";
import {AutocompleteList} from "./autocomplete-list";

@Directive({
    selector: "[ng2-autocomplete]", // The attribute for the template that uses this directive
    host: {
        "(keyup)": "onKey($event)" // Liten to keyup events on the host component
    }
})
export class AutocompleteDirective implements OnInit {
    // The search function should be passed as an input
    @Input("ng2-autocomplete") public search: (term: string) => Promise<Array<{ text: string, data: any }>>;
    // The directive emits ng2AutocompleteOnSelect event when an item from the list is selected
    @Output("ng2AutocompleteOnSelect") public selected = new EventEmitter();

    private term = "";
    private listCmp: ComponentRef<AutocompleteList> = undefined;
    private refreshTimer: any = undefined;
    private searchInProgress = false;
    private searchRequired = false;

    constructor( private viewRef: ViewContainerRef, private dcl: DynamicComponentLoader) { }
    /**
     * On key event is triggered when a key is released on the host component
     * the event starts a timer to prevent concurrent requests
     */
    public onKey(event: any) {
        if (!this.refreshTimer) {
            this.refreshTimer = setTimeout(
            () => {
                if (!this.searchInProgress) {
                    this.doSearch();
                } else {
                    // If a request is in progress mark that a new search is required
                    this.searchRequired = true;
                }
            },
            200);
        }
        this.term = event.target.value;
        if (this.term === "" && this.listCmp) {
            // clean the list if the search term is empty
            this.removeList();
        }
    }

    public ngOnInit() {
        // When an item is selected remove the list
        this.selected.subscribe(() => {
            this.removeList();
        });
    }

    /**
     * Call the search function and handle the results
     */
    private doSearch() {
        this.refreshTimer = undefined;
        // if we have a search function and a valid search term call the search
        if (this.search && this.term !== "") {
            this.searchInProgress = true;
            this.search(this.term)
            .then((res) => {
                this.searchInProgress = false;
                // if the term has changed during our search do another search
                if (this.searchRequired) {
                    this.searchRequired = false;
                    this.doSearch();
                } else {
                    // display the list of results
                    this.displayList(res);
                }
            })
            .catch(err => {
                console.log("search error:", err);
                this.removeList();
            });
        }
    }

    /**
     * Display the list of results
     * Dynamically load the list component if it doesn't exist yet and update the suggestions list
     */
    private displayList(list: Array<{ text: string, data: any }>) {
        if (!this.listCmp) {
            this.dcl.loadNextToLocation(AutocompleteList, this.viewRef)
            .then(cmp => {
                // The component is loaded
                this.listCmp = cmp;
                this.updateList(list);
                // Emit the selectd event when the component fires its selected event
                (<AutocompleteList>(this.listCmp.instance)).selected
                    .subscribe(selectedItem => {

                    this.selected.emit(selectedItem);
                });
            });
        } else {
            this.updateList(list);
        }
    }

    /**
     * Update the suggestions list in the list component
     */
    private updateList(list: Array<{ text: string, data: any }>) {
        if (this.listCmp) {
            (<AutocompleteList>(this.listCmp.instance)).list = list;
        }
    }

    /**
     * remove the list component
     */
    private removeList() {
        this.searchInProgress = false;
        this.searchRequired = false;
        if (this.listCmp) {
            this.listCmp.destroy();
            this.listCmp = undefined;
        }
    }
}

"use strict";
import {Component, Output, EventEmitter} from "@angular/core";

@Component({
    selector: "autocomplete-list",
    template: `<div class="dropdown-menu  search-results">
                    <a *ngFor="let item of list" class="dropdown-item" (click)="onClick(item)">{{item.text}}</a>
               </div>`, // Use a bootstrap 4 dropdown-menu to display the list
    styles: [".search-results { position: relative; right: 0; display: block; padding: 0; overflow: hidden; font-size: .9rem;}"]
})
export class AutocompleteList  {
    // Emit a selected event when an item in the list is selected
    @Output() public selected = new EventEmitter();

    public list;

    /**
     * Listen for a click event on the list
     */
    public onClick(item: {text: string, data: any}) {
        this.selected.emit(item);
    }
}

 "use strict";
import {Component} from "@angular/core";

import {AutocompleteDirective} from "../component/ng2-autocomplete/autocomplete";

@Component({
    selector: "my-cmp",
    directives: [AutocompleteDirective],
    template: `<input class="form-control" type="text" [ng2-autocomplete]="search()" (ng2AutocompleteOnSelect)="onItemSelected($event)" autocomplete="off">`
})
export class MyComponent  {

    /**
     * generate a search function that returns a Promise that resolves to array of text and optionally additional data
     */  
    public search() {
        return (filter: string): Promise<Array<{ text: string, data: any }>> => {
            // do the search
            resolve({text: "one item", data: null});
        };
    }

    /**
     * handle item selection
     */  
    public onItemSelected(selected: { text: string, data: any }) {
        console.log("selected: ", selected.text);
    }
}