Combine two array objects with exactly the same structure

Question

I am implementing a service that extracts a list of blacklist terms from a json file.

@Injectable()
export class BlacklistService {
  private readonly BLACKLIST_FOLDER = './assets/data/web-blacklist';
  private readonly blacklistEnglishTerms: any;
  private readonly blacklistFrenchTerms: any;

  constructor(
    public httpClient: HttpClient
  ) {
    this.blacklistEnglishTerms = this.httpClient.get(`${this.BLACKLIST_FOLDER}/en.json`);
    this.blacklistFrenchTerms = this.httpClient.get(`${this.BLACKLIST_FOLDER}/fr.json`);
  }

  public getAllBlackListTerms(): Observable<any> {
    return combineLatest([
      this.blacklistEnglishTerms,
      this.blacklistFrenchTerms
    ]);
  }
}

For reference, each json file looks like this:

{
  "blacklist": [
    "...",
    "...",
    "..."
  ]
}

I retrieve all the items in my component as follows:

this.blacklistService.getAllBlackListTerms().pipe(takeUntil(this.ngUnsubscribe)).subscribe(blacklistTerms => {
  console.log(blacklistTerms);
});

blacklistTerms returns as an array of 2 array objects. How do I combine these two objects into one object (both have the same structure).

You may check out this one

Yevhen Horbunkov
– Yevhen Horbunkov

2020-05-04 10:23:29 +00:00
Commented May 4, 2020 at 10:23 — Yevhen Horbunkov
– Yevhen Horbunkov, Commented May 4, 2020 at 10:23
Try with blacklistTerms.flatMap(x => x.blacklist)

Karan
– Karan

2020-05-04 10:25:54 +00:00
Commented May 4, 2020 at 10:25 — Karan
– Karan, Commented May 4, 2020 at 10:25

Ashish Ranjan · Accepted Answer · 2020-05-04 10:31:19Z

2

Given, you have known results, i.e. You know that the results of the bolth the Observbales would have only one key: blackList you can modify your service like:

public getAllBlackListTerms(): Observable<any> {
    return zip(
        this.blacklistEnglishTerms,
        this.blacklistFrenchTerms
    ).pipe(map([first, second]) => {
        return { blackList: [...first.blackList, ...second.blackList]};
    });
}

I have also, replaced combineLatest() with zip(), because you probably want the results only when both has emitted values.

edited May 4, 2020 at 10:31

answered May 4, 2020 at 10:25

Ashish Ranjan

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Comments

Shlok Nangia · Accepted Answer · 2020-05-04 10:33:36Z

2

Please try the following approach

var s  = [{a:[1,2,3]},{a:[6,7,8]}]
var obj = {}
for(let i in s){
    if(!obj['a']){obj['a'] = s[i]['a'];}
    else{
   obj['a'].push(...s[i]['a'])
    }
}

console.log(obj)

but here you need to manually define blacklist

answered May 4, 2020 at 10:33

Shlok Nangia

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Comments

takrishna · Accepted Answer · 2020-05-04 10:35:54Z

2

Blacklist is an array - even a simple concat can help !!

var blacklistEnglishTerms = {
  "blacklist": [
    "a",
    "b",
    "c"
  ]
}
var blacklistFrenchTerms = {
  "blacklist": [
    "e",
    "f",
    "g"
  ]
}
console.log(blacklistEnglishTerms.blacklist.concat(blacklistFrenchTerms.blacklist));

answered May 4, 2020 at 10:35

takrishna

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Comments

Muhammed Shafeeque · Accepted Answer · 2021-03-24 18:18:14Z

2

i think you please use concat().
the concat() is used for combine two arrays.

public getAllBlackListTerms(): Observable<any> {
    
   return combineLatest = this.blacklistEnglishTerms.concat(this.blacklistFrenchTerms);
  }

edited Mar 24, 2021 at 18:18

answered May 4, 2020 at 11:30

Muhammed Shafeeque

614 bronze badges

Comments

Karan · Accepted Answer · 2020-05-04 12:12:17Z

1

Try using flatMap() like blacklistTerms.flatMap(x => x.blacklist)

this.blacklistService.getAllBlackListTerms().pipe(takeUntil(this.ngUnsubscribe)).subscribe(blacklistTerms => {
  console.log(blacklistTerms.flatMap(x => x.blacklist));
});

Test is below.

let blacklistTerms = [
  { blacklist: [0, 1, 2] },
  { blacklist: [2, 3] }
];

console.log(blacklistTerms.flatMap(x => x.blacklist));

edited May 4, 2020 at 12:12

answered May 4, 2020 at 10:29

Karan

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