问题:

I don't want to use for loop to convert Object to Array like this! If doubled the process and slow down the performance of app (I'm using Ionic2 and Typescript, with Firebase)

for(let key in data) { array.push(value); }

Is there any solution to iterate object itself(shown in picture attached) using *ngFor.

Or I can convert this Object(shown in picture attached) to Array, so that can be iterable in *ngFor.

回答1:

You can use Object.keys(obj) to get named indexes. This will return an array structure which you can use/customize further. A sample use to iterate over object values may look like this

var persons = { 
    john: { age: 23, year:2010},
    jack: { age: 22, year:2011},
    jenny: { age: 21, year:2012}
}

Getting an iterator

var resultArray = Object.keys(persons).map(function(personNamedIndex){
    let person = persons[personNamedIndex];
    // do something with person
    return person;
});

// you have resultArray having iterated objects

回答2:

Adding toArray() on the pipe worked for me.

// Import toArray function
import { toArray } from 'rxjs/operators';

// Generic function to consume API
searchObjects(term: string): Observable<theObject[]> {
  requestUrl = this.url + term;
  return this.http.get<theObject[]>(requestUrl, httpOptions).pipe(
      // convert object to array
      toArray<theObject>()
  );
}