Reduce Array of Object Arrays to Array of Objects

Question

var data=[
  {name:'Sam',ssn:123, age:25, hobbies:[{name:'cricket'},{name:'football'}]},
  {name:'John',ssn:234, age:25, hobbies:[{name:'cricket'},{name:'football'}]},
  {name:'Mathew',ssn:345, age:25, hobbies:[{name:'cricket'},{name:'football'}]}
];

want to generate this to following format

[      
      {name:'Sam',ssn:123, age:25,hobbies:[{name:'cricket'}]},
      {name:'Sam',ssn:123, age:25,hobbies:[{name:'football'}]},
      {name:'John',ssn:234, age:25,hobbies:[{name:'cricket'}]},
      {name:'John',ssn:234, age:25,hobbies:[{name:'football'}]},
      {name:'Mathew',ssn:345, age:25,hobbies:[{name:'cricket'}]},
      {name:'Mathew',ssn:345, age:25,hobbies:[{name:'football'}]}
];

I have tried the following way. not getting any idea. I have added some basic functionality of reduce method but going forward not getting any idea to flatten it.

var flatten = data.reduce((curr, next) => {
  var temp = [];
  return (curr.hobbies = { name: "cricket" });
  temp.push(curr);
  return curr;
});

What should happen in the scenario that the input hobbies is an empty array? Following the logic of creating a separate row for each hobby this would mean removing the entry. — 3limin4t0r
– 3limin4t0r, Commented Mar 9, 2020 at 19:19

Maheer Ali · Accepted Answer · 2020-03-09 19:22:59Z

5

flatMap() is the best choice here.

var data=[
  {name:'Sam',ssn:123, age:25, hobbies:[{name:'cricket'},{name:'football'}]},
  {name:'John',ssn:234, age:25, hobbies:[{name:'cricket'},{name:'football'}]},
  {name:'Mathew',ssn:345, age:25, hobbies:[{name:'cricket'},{name:'football'}]}
];

const res = data.flatMap(x => x.hobbies.map(h => ({...x, hobbies: [h]})));
console.log(res)

edited Mar 9, 2020 at 19:22

answered Mar 9, 2020 at 19:13

Maheer Ali

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Đinh Carabus · Accepted Answer · 2020-03-09 19:18:23Z

0

var data=[
  {name:'Sam',ssn:123, age:25, hobbies:[{name:'cricket'},{name:'football'}]},
  {name:'John',ssn:234, age:25, hobbies:[{name:'cricket'},{name:'football'}]},
  {name:'Mathew',ssn:345, age:25, hobbies:[{name:'cricket'},{name:'football'}]}
];

data = data.reduce((a, x) => [
  ...a, 
  ...x.hobbies.map(h => ({...x, hobbies: [h]}))
], []);

console.log(data);

edited Mar 9, 2020 at 19:18

answered Mar 9, 2020 at 19:11

Đinh Carabus

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