RxJs- Observable - How to fetch data from JSON Object

Question

I have a JSON response observable as below.I would like to get data from this observables in two seperate array such as [abc,xyz] and [aa,bb]. Is it possible using rx observables map and switchmap to get two arrays in the same observable.

this.data$ = Observable.of({
      "data": [
        {
          "firstname": "abc",
          "lastname": "aa"
        },
         {
          "firstname": "xyz",
          "lastname": "bb"
        }
      ]
    })  .map(res => res.data)
      .switchMap(dataArray => {
        return Observable.from(dataArray);
      })
      .map((arrayResp: any) => {
        return ( arrayResp.firstname);
      }).toArray()

Here iam only able to get one array. Is it possible to get two arrays in this method only.

You are getting only one object, you want to get the array of all the objects ? Is it what you mean ? — ibenjelloun
– ibenjelloun, Commented May 2, 2018 at 9:02
Yes i want to get array of firstname and lastname seperately — FrontEndDeveloper
– FrontEndDeveloper, Commented May 2, 2018 at 9:23

Parzh · Accepted Answer · 2021-12-01 08:59:24Z

3

You could simply use the arrays map function :

.pipe(
    map(res => res.data),
    map(a => ({
        firstnames: a.map(_ => _.firstname),
        lastnames: a.map(_ => _.lastname),
    })),
);

Here is a running example.

edited Dec 1, 2021 at 8:59

Parzh

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answered May 2, 2018 at 10:00

ibenjelloun

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3 Comments

FrontEndDeveloper Over a year ago

Can we not do this without the buffercount?

ibenjelloun Over a year ago

Sorry, I can't even understand why I ended up with something that complicated for this simple task. I edited my answer and also the stackblitz.

FrontEndDeveloper Over a year ago

Thanks for the quick response!

Pranay Rana · Accepted Answer · 2018-05-02 10:05:22Z

2

you have json string so you need to do like this in your switchMap method

 .switchMap(dataArray => {
        return Observable.from(JSON.parse( dataArray));
      })

or you can do like this also

this.data$ = Observable.of(JSON.parse(`{
      "data": [
        {
          "firstname": "abc",
          "lastname": "aa"
        },
         {
          "firstname": "xyz",
          "lastname": "bb"
        }
      ]
    }`).subscribe(res=> console.log(res.data));

answered May 2, 2018 at 10:05

Pranay Rana

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