无法订阅 BehaviorSubject
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【中文标题】无法订阅 BehaviorSubject【英文标题】:Unable to subscribe to BehaviourSubject 【发布时间】:2021-09-05 01:49:27 【问题描述】:我有一个奇怪的问题。我在一项服务中定义了BehaviourSubject
,以在用户更改语言时传播更改。在许多组件中,当BehaviourSubject
更改时,我会做一些事情。它适用于除一个以外的所有组件,我不知道为什么。
我的代码:
@Injectable()
export class I18nLanguagesService
private activeLang: I18NLanguage = LANGUAGES.find(ln => ln.name === 'Español');
activeLangSubject = new BehaviorSubject<I18NLanguage>(null);
setActiveLang(language: I18NLanguage): void
this.activeLang = language;
this.activeLangSubject.next(language);
getActiveLang(): I18NLanguage
return this.activeLang;
getLanguages(): I18NLanguage[]
return LANGUAGES;
在CoreModule
的providers
部分声明,在app.module
中导入一次。
用法:
组件 1(在
shared.module
中定义)
这个很好用。每次主题发出一个值时,它都会调用服务。
constructor(private statesServ: StatesService, private i18nSrv: I18nLanguagesService)
this.i18nSrv.activeLangSubject
.pipe(
tap(() =>
this.statesMultiCtrl.reset();
console.log('SELECTOR | In tap')
),
switchMapTo(this.statesServ.getStatesList())
)
.subscribe(states =>
this.states = states;
this.statesFiltered = this.states;
);
管道(在
shared.module
中定义)
它也适用于管道:
export class AsyncI18nDatePipe implements PipeTransform
constructor(private i18nS: I18nLanguagesService)
transform(value: Date | null | undefined, format = 'mediumDate', timezone?: string): Observable<string>
if (value)
return this.i18nS.activeLangSubject.pipe(map(localeId => formatDate(value, format, localeId.countryCode, timezone)));
return of('');
故障出在这个组件中,也在shared.module
中定义:
constructor(private formBuilder: FormBuilder, private valUsuServ: ValidationUsersService, private cmpServ: CampaignsService, private i18nService: I18nLanguagesService)
this.filters = this.formBuilder.group(
idClient: new FormControl(null),
idProject: new FormControl( value: null, disabled: true ),
sourceLanguage: new FormControl( value: null, disabled: true ),
targetLanguage: new FormControl( value: null, disabled: true ),
rangeDate: new FormGroup(
dateFrom: new FormControl(null),
dateTo: new FormControl(null),
),
idItem: new FormControl( value: null, disabled: false ),
searchWords: new FormControl( value: null, disabled: true ),
itemState: new FormControl(null),
category: new FormControl( value: null, disabled: true ),
validationUser: new FormControl( value: null, disabled: true ),
campaing: new FormControl(null),
priorityOrd: new FormControl('asc'),
dateOrd: new FormControl('asc'),
categoryOrd: new FormControl('asc'),
campaingOrd: new FormControl('asc'),
);
ngOnInit(): void
this.i18nService.activeLangSubject.pipe(tap(lang => console.log('FILTERS | In tap -->', lang)));`
当我输入有问题的组件时,它会记录所有内容:
但是当我更改语言时,仅在“有效”的组件中,它会记录更改:
我不知道为什么会发生这种行为,任何帮助将不胜感激。感谢阅读!!
【问题讨论】:
你在哪里订阅 observable?你说它有时有效,但你没有包含任何代码,你在失败的组件中实际使用subscribe
或async
管道订阅。
【参考方案1】:
在您的“失败的组件”中。尝试订阅更改,例如:
this.i18nService.activeLangSubject.pipe(tap(lang => console.log('FILTERS | In tap -->', lang))).subscribe(() => console.log("changed"));
【讨论】:
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