Angular 2 Observable输入在订阅后不更新UI

时间:2016-12-19 16:20:04

标签: angular angular2-components

我有一个搜索框的子组件。用户输入某些输入并按下搜索按钮。这会发出一个“搜索”事件,父组件随后会使用搜索参数调用搜索服务,并将结果分配给子组件的Observable输入属性。在子组件输入属性的setter中,我订阅了Observable,然后映射结果。我的问题是,在设置结果之前UI不会刷新,直到发生鼠标移动或按钮点击等事件。我想我需要使用ngZone调用subscribe我的问题是为什么我必须这样做?在我的搜索组件的另一种风格中,父组件负责调用subscribe,然后将结果分配给子组件的输入属性,这可以按预期工作。非常感谢对这两种方法的不同之处以及最佳解决方法的一些解释。

以下是我的搜索框(子)组件。

transform="translate(50 50)"

以下是父组件代码。如果我在onSearch中绕过注释和未注释的行,我的结果会立即显示。否则,我需要通过移动鼠标,单击或按键来触发另一个Angular UI tick。非常感谢您的帮助!

import {
    AfterViewInit, ChangeDetectorRef, ChangeDetectionStrategy, Component,
    ElementRef, EventEmitter, Input, OnChanges,
    Output, SimpleChanges, ViewChild }                                  from '@angular/core';
import { ControlValueAccessor }                                         from '@angular/forms';
import {
    ApplicationService, PromptActions, PromptType,
    SearchItem, SearchItemType, SearchType, SearchArgs,
    UserPromptRequest
} from '../../../core';
import { Observable } from 'rxjs/Observable';
import { Subscription } from 'rxjs/Subscription';
import { PanelBarItemModel }                                            from '@progress/kendo-angular-layout';

@Component({
    moduleId: module.id,
    selector: 'search-box',
    templateUrl: 'search-box.component.html',
    styleUrls: ['search-box.component.css'],
    changeDetection: ChangeDetectionStrategy.OnPush
})
export class SearchBoxComponent implements ControlValueAccessor {

    constructor(private cd: ChangeDetectorRef, private applicationService: ApplicationService) { }

    @Input() searchText: string;

    @Output() search: EventEmitter<SearchArgs> = new EventEmitter();

    private _searchObservable: Observable<SearchItemType[]>;
    @Input() 
    set searchObservable(val: Observable<SearchItemType[]>) {
        this._searchObservable = val;
        if (this._searchObservable) {
            this.searchSubscription = this._searchObservable.subscribe(r => this.resp(r));
        }
    }

    private _selectedItem: SearchItem;
    @Input()
    set selectedItem(val: SearchItem) {
        this._selectedItem = val;
        this.propagateChange(this._selectedItem);
    }

    get selectedItem(): SearchItem {
        return this._selectedItem;
    }

    searchResultsModel: PanelBarItemModel[];

    private _searchResults: SearchItemType[];
    @Input()
    set searchResults(val: SearchItemType[]) {
        this._searchResults = val;
        this.setUpPanelBarModel();
    }
    get searchResults(): SearchItemType[] {
        return this._searchResults;
    }

    private setUpPanelBarModel() {
        this.isSearching = false;
        this.cd.markForCheck();
    }   

    onSearch() {
        this.isResultsPopupVisible = true;
        this.searchResults = undefined;
        let searchArgs = new SearchArgs(this.searchText, this.selectedSearchTypeValue);
        this.search.emit(searchArgs);
        this.isSearching = true;
        this.cd.markForCheck();
    }

    resp(r: any) {
        this.searchResults = r;
        this.cd.markForCheck();
    }

    writeValue(obj: any): void {
        this.selectedItem = obj;
    }

    private propagateChange = (_: any) => { };

    registerOnChange(fn: any): void {
        this.propagateChange = fn;
    }        

    registerOnTouched(fn: any): void { } // Don't need

}

1 个答案:

答案 0 :(得分:0)

使用ChangeDetectionStrategy.OnPush,您仅限于通过@Input@Output属性更改检测。否则,您必须手动通知Angular有关更改。

尝试将服务中的搜索结果连接到您用来显示结果的@Input属性(ClientTypeListComponent.searchResults ??)。此外,我不确定更改检测如何与SearchBoxComponent.searchResults中的getter / setter一起使用;您可以尝试将其重写为普通@Input属性。