Angular2不能在另一个订阅中使用一个订阅的值(可观察) [英] Angular2 cannot use the values of a subscribe in another subscribe (observable)
问题描述
我想在另一个方法中使用订阅方法中的值,但是它给我未定义的信息,因为它不是异步的.有没有一种方法可以将这些值一起使用?我想在下面的订阅方法中再次使用this.internships
,但是它变得不确定.谢谢您的帮助!
I wanted to use a value from a subscribe method in another one, but it gives me undefined because it is not async. Is there a method to use those values together? I want to use this.internships
another time in the following subscribe method but it becomes undefined. Thank you for helping!
代码:
ngOnInit(): void {
this._internshipAssignmentService.getInternshipAssignments()
.subscribe(internships => { this.internships = internships; <---- value which gives an object
this.internshipsHelper = internships; console.log(this.internships)},
error => this.msgs.push({
severity: 'error',
summary: 'Error',
detail: 'Er is een onverwachte fout opgetreden.'
}));
this.sub = this._route.params.subscribe(
params => {
let id = +params['id'];
this._internshipAssignmentService.getAllFavorites()
.subscribe(f => {
this.favorites = f;
this.favorite = this.getFavoritesFromIdStudent(1);
console.log(this.internships); <----- value which gives undefined
this.getFavorites(this.favorite);
});
}
);
}
推荐答案
this.internships
是undefined
,因为这些调用是异步的,所以您可以获得更多信息
this.internships
is undefined
because these calls are asynchronous, you can get more informations here.
还请注意,您正在使用多个订阅,这不是一个好习惯,您应该使用一些
Also note that you are using multiple subscription, which is not a good practice, you should combine your observable using some operators like switchMap
map
,pluck
, etc.
ngOnInit(): void {
this.sub = this._internshipAssignmentService.getInternshipAssignments().do((internships) => {
this.internships = internships; // not needed if you just use it in next callbacks
this.internshipsHelper = internships;
console.log(this.internships)
}).catch(error => {
this.msgs.push({
severity: 'error',
summary: 'Error',
detail: 'Er is een onverwachte fout opgetreden.'
})
}).switchMap(internships => this._route.params.pluck('id').switchMap(id => {
return this._internshipAssignmentService.getAllFavorites().do(f => {
this.favorites = f;
this.favorite = this.getFavoritesFromIdStudent(1);
this.getFavorites(this.favorite);
})
}))
.subscribe();
}
这篇关于Angular2不能在另一个订阅中使用一个订阅的值(可观察)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!