I'm currently working on developing a basic forum.
One of the tasks at hand involves filtering the posts using RxJS and dealing with some challenges related to .pipe and .filter methods.
Here is what I am attempting to achieve:
- Retrieve the list of posts from an in-memory API endpoint
api/posts. The http.get method returns anObservable<Post[]> - Go through each individual post in the
Observable<Post[]>and filter out only those posts with an id of1(assuming there is only one post with an id of1) - Display any errors or success messages in the console
However, when applying the filter, it seems to be selecting the entire Post[] array instead of individual elements within the array.
This is my code snippet:
getPosts(): Observable<Post[]> {
// Define the URL for the posts
const url = this.postsUrl;
// Using http.get to retrieve an Observable<Post[]>
return this.http.get<Post[]>(url)
.pipe(
filter(
post: Post => post.id == 1
),
// Log success message
tap(posts => console.log('Posts fetched.')),
// Error handling
catchError(this.handleError('getPosts', []))
);
}
The error I encountered:
Property 'id' does not exist on type 'Post[]'
In all the examples I've reviewed, the filter function was able to iterate through each value individually within the Post[] array. It should allow access to each element as a Post type.
Update following a solution suggestion
The final revised code segment, based on the provided solution, is structured as follows:
In posts.service.ts:
getPosts(): Observable<Post[]> {
const url = this.postsUrl;
// Get the observable containing an array of Posts
return this.http.get<Post[]>(url)
.pipe(
// Log success message
tap(posts => console.log('Posts fetched.')),
// Error handling
catchError(this.handleError('getPosts', []))
);
}
In posts.component.ts:
private getPosts(): void {
this.service.getPosts()
// Mapping posts to a filtered version
.map(
posts => posts.filter(
post => post.from_board_id == this.from_board_id
)
)
// Subscribe to the results
.subscribe(
posts => this.posts = posts
)
;
}