angular2打字稿无法分配给this.object属性

Question

I am attempting a project in angular2 and typescript, and I am having some inexplicable problems. For some reason, I cannot assign data to a class property.

I have a pair of class properties defined like this:

public loadResultMessages: string[];
public book: Book;

I have a method where I'm calling a service like this:

getBookByCode() {

    this.http.get('/api/book/loadbycode?code=' + this.bookCode)
        .subscribe(result => {

            var object = result.json();

            console.log(object);

            this.loadResultMessages = object.loadResultMessages;
            this.book = object.book;

    });
}

I have verified that I am getting data back in the object, but even after attempting to assign data to the two properties, they say undefined. How can that be?

EDIT: Okay, I am messing around with Visual Studio 2017 and setting breakpoints in my JavaScript. I was mousing over the variables and it was telling me they were undefined. However, when I actually log them out to the console they are populated. Other variables I can mouse over and they show the results. I'm not sure if this is some kind of timing issue or a bug in VS?

I think I'm also suffering some major caching issues. Just putting the extra console.log() calls in there suddenly has made my code start working.

Answer 1

Mostly your service should be returning an Observable of an object or array of objects.

getBookByCode(bookCode) : Observable<any[]> {

    return this.http.get('/api/book/loadbycode?code=' + bookCode)
                    .map((response: Response) => <any[]>response.json())
                    .do(data => console.log("data we got is " + JSON.stringify(data)))
                    .catch(this.handleError);
    });
}

In your component you should be subscribing to it in your constructor as

constructor(private serviceObject:ServiceName){
    this.serviceObject.getBookByCode(this.bookCode)
                    .subscribe(results => this.results = results,
                    error =>console.log(error);
    }   
}