CODEWITHSUNDEEP
javascriptnode.js
Ricardo Martin
Ricardo Martin

Reputation: 129

Convert JSOn object into a flat JSON Array

I have a nested JSON object that getting from a mongoDB query that i would like to convert into flat JSON array .I am using nested mondo documents, but i would like to show the data in a more readble way. My JSON has the following structure:

{
 "country": "Country A",
 "_id": "1"
 "regions": [{
        "region": "region A1",
        "cities": [{
                "city": "city A11"
            },
            {
             "city": "city A12"
            }
        ]
        },
        {
            "region": "region A2",
            "cities": [{
                    "city": "city A21"
                },
                {
                    "city": "city A22"
                }
            ]
        }
    ]
}

I want to show only the important information and not the structure of the nested array. How i can modify my data in Javascript on order to achieve the following result.

[{
"country": "Country A",
"region":"Region A1",
"city": "City A11"
},
 {
"country": "Country A",
"region":"Region A1",
"city": "City A12"
},

-------------

{
"country": "Country A",
"region":"Region A2",
"city": "City A22"
}]

I have tried to do in this way but it´s not working.

exports.get_places = (req, res, next) => {
Place.findOne({_id:req.params.id})
    .then(data => {
      let flat = arr.reduce((arr, {country, regions}) => {
          regions.forEach(({region, cities}) => {
          cities.forEach(({city}) => {
       arr.push({country, region, city})
    })
})
return arr
}, [])
console.log(flat)
    })
    .catch(error => {
        return next(error);
    });
}

Upvotes: 0

Views: 2738

Answers (3)

mster
mster

Reputation: 898

As is the typical case for Node... there's a package for that! A popular one is called flat (zero deps!!). https://www.npmjs.com/package/flat

From their README:

var flatten = require('flat')
 
flatten({
    key1: {
        keyA: 'valueI'
    },
    key2: {
        keyB: 'valueII'
    },
    key3: { a: { b: { c: 2 } } }
})
 
// {
//   'key1.keyA': 'valueI',
//   'key2.keyB': 'valueII',
//   'key3.a.b.c': 2
// }

You can also implement your own! :)

If you need some hints, I've implemented one in a recent project of mine except it returns an array.

Check it out: https://github.com/mster/fireferret/blob/e99b6e8f23d4a0783c8a0706cd163093936d6c69/lib/utils/flatmapper.js#L6-L50

Upvotes: 0

ic3b3rg
ic3b3rg

Reputation: 14927

I believe this will perform the transformation you seek:

const country = {
  "country": "Country A",
  "_id": "1",
  "regions": [
    {
      "region": "region A1",
      "cities": [
        {
          "city": "city A11"
        },
        {
          "city": "city A12"
        }
      ]
    },
    {
      "region": "region A2",
      "cities": [
        {
          "city": "city A21"
        },
        {
          "city": "city A22"
        }
      ]
    }
  ]
};

const flat = country.regions.flatMap(({region, cities}) =>
  cities.map(({city}) => ({country: country.country, region, city})
));

console.log(flat);

Upvotes: 1

Marcos
Marcos

Reputation: 338

I think you need use map function, and transfomr every object in nested arrays as the object you want to obtain. If I undesrstand you good you will need somthing like this:

let desiredArray = country.region.map(x => {
    country:x.country,
    region:x.region,
    cities:x.city
})

its little confuse to undestand what you really want but I think you can start to work with that

Upvotes: 0

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