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[英]Angular unit testing TypeError: Cannot read property 'subscribe' of undefined
[英]Cannot read property 'subscribe' of undefined TypeError
我正在开发一个Ionic应用程序,并且有以下方法调用了observable:
getCountryById(id: number): Promise<Country> {
return new Promise((resolve, reject) => {
this.getCountries().subscribe(countries => {
for (let country of countries) {
if (country.Id == id) {
resolve(country);
}
}
resolve(undefined);
}, err => reject(err));
})
}
另一种方法:
getCountries(): Observable<Country[]> {
if (this.countries) {
return Observable.of(this.countries);
} else if (this.countriesObservable) {
return this.countriesObservable;
} else {
this.storage.get(AppSettings.STORAGE_KEYS.LANGUAGE_APP).then(
language=>{
this.countriesObservable = this.http.get(AppSettings.API_URL + 'api/Countries?locale=' + language).map(json => {
delete this.countriesObservable; // when the cached countries is available we don't need the `countriesObservable` reference anymore
this.countries = json as Country[];
this.countries = this.countries.sort(function (a, b) { return (a.Name > b.Name) ? 1 : ((b.Name > a.Name) ? -1 : 0); });
return this.countries;
}).share();
}
).catch(err=>{
});
return this.countriesObservable;
}
}
我很确定我要返回错误的数据。 我应该如何重构第二种方法以返回有效的Observable,以便第一种方法可以解决这个问题。 谢谢你的帮助。
您的问题是,当this.countriesObservable
undefined
,您正在调用this.storage.get(...).then(...)
。 在tha的回调内,您可以设置this.countriesObservable
。
问题是,当你到达return this.countriesObservable
,回调then
没有执行,所以你还是回来undefined
。
您必须分配this.countriesObservable
到一个新的Observable
之前调用this.storage.get
(也许一个Subject
),然后,里面then
,你只听你要回报可观的,其调用内部subscribe
,养活this.countriesObservable
与所需数据一起查看:
const _subject = new Subject<Country[]>();
this.countriesObservable = _subject;
this.storage.get(AppSettings.STORAGE_KEYS.LANGUAGE_APP).then(
language=>{
this.http.get(AppSettings.API_URL + 'api/Countries?locale=' + language).map(json => {
delete this.countriesObservable; // when the cached countries is available we don't need the `countriesObservable` reference anymore
this.countries = json as Country[];
this.countries = this.countries.sort(function (a, b) { return (a.Name > b.Name) ? 1 : ((b.Name > a.Name) ? -1 : 0); });
return this.countries;
}).subscribe(countries => _subject.next(countries));
}
).catch(err=>{});
return this.countriesObservable;
您可能需要进行一些调整,但这是个主意。 希望它能为您服务。
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