Converting async responce of Array of Arrays into Object

Question

I am trying to convert Array of Arrays that I get from Observable into single array of objects. This is my code:

    this.jobsService.jobsUpdated.pipe(
    map(
     (jobsData)=> {
      return jobsData.map(
        (job)=>{
        return  job.parts.map((part)=>{ return part })
        }
      )
     }
    )
   ).subscribe(
      (partsData)=>{
         console.log('partsdata', partsData)
      }
    );

This is the data format I am getting back:

    [
     [
       {partName:1, number:10, quantity: 100}
     ],
     [
       {partName:2, number:20, quantity: 200},
       {partName:3, number:30, quantity: 300}
     ],
     etc...
    ]

Please help to convert this data, hopefully in the pipe method, into :

    [
      {partName:1, number:10, quantity: 100},
      {partName:2, number:20, quantity: 200},
      {partName:3, number:30, quantity: 300}
    ]

Pankaj Parkar · Accepted Answer · 2022-12-20 10:48:59Z

1

Use reduce and no need of using inner map

Why reduce? - To generate single output based on multiple inputs.

this.jobsService.jobsUpdated.pipe(
    map((jobsData)=> {
      return jobsData.reduce(
        (acc, job)=>{
          acc.push(...job.parts)
          return acc;
        }
      , [])
    })
);

Alternatively concat can also be used

this.jobsService.jobsUpdated.pipe(
   (jobsData)=> jobsData.reduce(
      (acc, job)=> acc.concat(job.parts), [])
   })
);

edited Dec 20, 2022 at 10:48

answered Jul 30, 2022 at 7:06

Pankaj Parkar

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Comments

Pankaj Parkar · Accepted Answer · 2022-07-30 07:42:43Z

0

If you just want a flat array:

this.jobsService.jobsUpdated
  .pipe(
     pluck('parts'),
     map((parts)=> parts.flat())
  )

edited Jul 30, 2022 at 7:42

Pankaj Parkar

136k23 gold badges241 silver badges307 bronze badges

answered Jul 30, 2022 at 7:06

Eugene

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3 Comments

Pankaj Parkar Over a year ago

Not sure, how it will make sure to extract parts property only?

Eugene Over a year ago

Yes, I forgot about this insignificant detail, I'll add it now

Alex Over a year ago

Thank you for your answer! I did not know about pluck. I will learn more about it.

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