Using map function in javascript

Question

My json response structure:

[
    {
        "id": 14,
        "groupname": "Angular",
        "createdAt": "2017-12-15T15:06:39.000Z",
        "updatedAt": "2017-12-15T15:06:39.000Z",
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "123456789"
                }
            },
            {
                "id": 2,
                "contact": {
                    "id": 21,
                    "gsm": "987654321"
                }
            }
        ]
    },
    {
        "id": 15,
        "groupname": "React",
        "createdAt": "2017-12-15T15:06:45.000Z",
        "updatedAt": "2017-12-15T15:06:45.000Z",
        "contactgroups": [
            {
                "id": 3,
                "contact": {
                    "id": 21,
                    "gsm": "987654321"
                }
            }
        ]
    },
    {
        "id": 16,
        "groupname": "Vue",
        "createdAt": "2017-12-15T15:06:51.000Z",
        "updatedAt": "2017-12-15T15:06:51.000Z",
        "contactgroups": []
    },
    {
        "id": 17,
        "groupname": "NodeJs",
        "createdAt": "2017-12-17T16:07:38.000Z",
        "updatedAt": "2017-12-17T16:07:38.000Z",
        "contactgroups": []
    },
    {
        "id": 18,
        "groupname": "RxJS",
        "createdAt": "2017-12-21T05:50:50.000Z",
        "updatedAt": "2017-12-21T05:50:50.000Z",
        "contactgroups": []
    }
]

i have two objects inside contactgroups array, so i need to return contactsCount as 2,

if i have one object inside contactgroups i need to return contactsCount as 1, is it possible to do with map method in Javascript?

I want final output like

[
    {
        "id": 14,
        "groupname": "Angular",
        "createdAt": "2017-12-15T15:06:39.000Z",
        "updatedAt": "2017-12-15T15:06:39.000Z",
        "contactsCount: 2,
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "123456789"
                }
            },
            {
                "id": 2,
                "contact": {
                    "id": 21,
                    "gsm": "987654321"
                }
            }
        ]
    },
    {
        "id": 15,
        "groupname": "React",
        "createdAt": "2017-12-15T15:06:45.000Z",
        "updatedAt": "2017-12-15T15:06:45.000Z",
        "contactsCount: 1,
        "contactgroups": [
            {
                "id": 3,
                "contact": {
                    "id": 21,
                    "gsm": "987654321"
                }
            }
        ]
    },
    {
        "id": 16,
        "groupname": "Vue",
        "createdAt": "2017-12-15T15:06:51.000Z",
        "updatedAt": "2017-12-15T15:06:51.000Z",
        "contactsCount: 0,
        "contactgroups": []
    },
    {
        "id": 17,
        "groupname": "NodeJs",
        "createdAt": "2017-12-17T16:07:38.000Z",
        "updatedAt": "2017-12-17T16:07:38.000Z",
        "contactsCount: 0,
        "contactgroups": []
    },
    {
        "id": 18,
        "groupname": "RxJS",
        "createdAt": "2017-12-21T05:50:50.000Z",
        "updatedAt": "2017-12-21T05:50:50.000Z",
        "contactsCount: 0,
        "contactgroups": []
    }
]

see now i have contactsCount inside my final output.

This is my api code:

exports.getNewGroupForProfsms = (req, res) => {
    Group.findAll({
        include: [{
            model: ContactGroup,
            attributes: ['id'],
            include: [{
                model: Contact,
                attributes: ['id', 'gsm']
            }]
        }],
    }).then(data => {
        // i am getting json here// how to do map here?
        return res.status(200).send(data);
    }).catch(err => {
        return res.status(400).send(err.message);
    });
};

gurvinder372 · Accepted Answer · 2017-12-21 10:15:28Z

2

Use map (or forEach)

data.map( s => ( s.contactsCount = s.contactgroups.length, s ) );

Demo

var data = [
    {
        "id": 14,
        "groupname": "Angular",
        "createdAt": "2017-12-15T15:06:39.000Z",
        "updatedAt": "2017-12-15T15:06:39.000Z",
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "123456789"
                }
            },
            {
                "id": 2,
                "contact": {
                    "id": 21,
                    "gsm": "987654321"
                }
            }
        ]
    }
];

data.map( s => ( s.contactsCount = s.contactgroups.length, s ) );

console.log(data);

answered Dec 21, 2017 at 10:15

gurvinder372

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9 Comments

Sameer Over a year ago

thank you, see my updated question i want to get this in response.

gurvinder372 Over a year ago

Did you tried using this code at that place? You just need to replace data with appropriate variable or JSON path.

Sameer Over a year ago

yes i dont get contactsCount. can you post full answer with my api code? it will be really helpful to me

gurvinder372 Over a year ago

can you share the structure of the data in your api code?

gurvinder372 Over a year ago

Just put this line before return statement data = data.map( s => ( s.contactsCount = s.contactgroups.length, s ) );

|

Ori Drori · Accepted Answer · 2017-12-21 10:14:54Z

1

You can map the array, and use Object#assign to return a new object with the count:

const arr = [{"id":14,"groupname":"Angular","createdAt":"2017-12-15T15:06:39.000Z","updatedAt":"2017-12-15T15:06:39.000Z","contactgroups":[{"id":1,"contact":{"id":20,"gsm":"123456789"}},{"id":2,"contact":{"id":21,"gsm":"987654321"}}]}];

const result = arr.map((o) => Object.assign({ contactsCount: o.contactgroups.length || 0 }, o));

console.log(result);

answered Dec 21, 2017 at 10:14

Ori Drori

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1 Comment

Sameer Over a year ago

thank you, see my updated question i want to get this in response.

Ben Aston · Accepted Answer · 2017-12-21 10:42:25Z

1

// ...    
.then((data) => 
    res.status(200).send(data.map((i) => 
        ((i.contactsCount = i.contactgroups.length), i))))
// ...

...but it is not clear why you want to do this, given that simply retrieving the length of the contactgroups array is trivial.

edited Dec 21, 2017 at 10:42

answered Dec 21, 2017 at 10:34

Ben Aston

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6 Comments

Sameer Over a year ago

This is my exact problem , stackoverflow.com/questions/47919818/…

Sameer Over a year ago

i cant get answer , so i am doing like this

Ben Aston Over a year ago

I added a missing parenthesis, pls try again.

Sameer Over a year ago

if i send request via postman still i dont get contactsCount in response, i think posting full api code will be really helpful to me :)

Ben Aston Over a year ago

Check you are hitting the right endpoint and that the server has been restarted. Stick a debugger in to check the code is being run.

|

Saumya Shekhar · Accepted Answer · 2017-12-21 10:21:15Z

You can use data.map(contactgroupcount) like below.

var data =  [
    {
        "id": 14,
        "groupname": "Angular",
        "createdAt": "2017-12-15T15:06:39.000Z",
        "updatedAt": "2017-12-15T15:06:39.000Z",
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "123456789"
                }
            },
            {
                "id": 2,
                "contact": {
                    "id": 21,
                    "gsm": "987654321"
                }
            }
        ]
    }
]

    function contactgroupcount(obj) {
       obj["contactsCount"] = obj.contactgroups.length;
        return obj;
    }

    data.map(contactgroupcount);

Sameer · Accepted Answer · 2017-12-21 11:28:55Z

0

Finally this one worked for me:

exports.getNewGroupForProfsms = (req, res) => {
  Group.findAll({
    include: [{
      model: ContactGroup,
      attributes: ['id'],
      include: [{
        model: Contact,
        attributes: ['id', 'gsm']
      }]
    }],
  }).then(data => {
    // change happen here
    return res.status(200).send(data.map((x) => {
      // assign contactsCount to each row
      return Object.assign({
        contactsCount: x.contactgroups.length,
      }, x.toJSON()) // update toJSON have a try
    }));
  }).catch(err => {
    return res.status(400).send(err.message);
  });
};

answered Dec 21, 2017 at 11:28

Sameer

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