How to add data in json object from another object?

Question

I have a data object which has some data now i want to create another object mapdata2 which has same structure as data. but my code did not work and also shows some syntax error. I have created mapdata2 object and empty features array inside it.
It shows an error:

TypeError: i.features is undefined

<script>      
data = {"type": "FeatureCollection",
        "features": [
           {
                "type": "Feature", 
              "properties": 
              {
                "title": "ABC", "startDate": 1100, "endDate": 1200, "latitude": 60.814, "longitude": 11.845, "content": "content." 
              },
              "geometry": 
              {
                "type": "Point","coordinates": [ 60.814, 11.845, 1]
              } 
           },
           {
                "type": "Feature", 
              "properties": 
              {
                "title": "XYZ", "startDate": 1100, "endDate": 1200, "latitude": 40.814, "longitude": 15.845, "content": "content." 
              },
              "geometry": 
              {
                "type": "Point","coordinates": [ 40.814, 15.845, 1]
              } 
           },

         ]
     }
               mapdata2 = {
                  "type": "FeatureCollection",
                  "features" : []
                };

                for(i in data){
                    console.log(i);
                          mapdata2.features.push({
                            type:"Feature",
                            properties : { title: i.features.properties.title, startDate: i.features.properties.startDate, endDate: i.features.properties.endDate latitude: i.features.properties.latitude, longitude: i.features.properties.longitude, content: i.features.properties.content },
                            geometry : { type: "Point", coordinates: i.features.geometry.coordinates }
                        })
                  }
                  console.log(mapdata2);

 </script>

Omri Attiya · Accepted Answer · 2019-09-03 12:40:55Z

That happens because you are trying to access features for each i in data, but the first iis "type" and it doesn't have features in it.

So I modified your code so that you iterate only over the "features", and for each feature you do what you did, and now it's working.

data = {
  "type": "FeatureCollection",
  "features": [{
      "type": "Feature",
      "properties": {
        "title": "ABC",
        "startDate": 1100,
        "endDate": 1200,
        "latitude": 60.814,
        "longitude": 11.845,
        "content": "content."
      },
      "geometry": {
        "type": "Point",
        "coordinates": [60.814, 11.845, 1]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "title": "XYZ",
        "startDate": 1100,
        "endDate": 1200,
        "latitude": 40.814,
        "longitude": 15.845,
        "content": "content."
      },
      "geometry": {
        "type": "Point",
        "coordinates": [40.814, 15.845, 1]
      }
    },

  ]
}
mapdata2 = {
  "type": "FeatureCollection",
  "features": []
};

data.features.forEach((feature) => {
  mapdata2.features.push({
    type: "Feature",
    properties: {
      title: feature.properties.title,
      startDate: feature.properties.startDate,
      endDate: feature.properties.endDate,
      id: feature.properties.id,
      latitude: feature.properties.latitude,
      longitude: feature.properties.longitude,
      content: feature.properties.content
    },
    geometry: {
      type: "Point",
      coordinates: feature.geometry.coordinates
    }
  })

});
console.log(mapdata2);

Thanks. @Omri Attiya. Now its working. I have a question. In my data there is also an array 'coordinates' in geometry. if i want to add data dynamically in this array so do i need to create one more array on top. ?
@MuhammadHassan If you want to add data to an array, you just need to use push. For example: mapdata2.features[0].geometry.coordinates.push(777);

Nabeel Mehmood · Accepted Answer · 2019-09-03 12:43:56Z

You dont need to map or loop at all if you simply wish to copy the json list to mapdata2.

mapdata2.features = data.features
console.log(mapdata2);

This will do what you wish to accomplish without having to loop at all.

    
data = {"type": "FeatureCollection",
        "features": [
           {
                "type": "Feature", 
              "properties": 
              {
                "title": "ABC", "startDate": 1100, "endDate": 1200, "latitude": 60.814, "longitude": 11.845, "content": "content." 
              },
              "geometry": 
              {
                "type": "Point","coordinates": [ 60.814, 11.845, 1]
              } 
           },
           {
                "type": "Feature", 
              "properties": 
              {
                "title": "XYZ", "startDate": 1100, "endDate": 1200, "latitude": 40.814, "longitude": 15.845, "content": "content." 
              },
              "geometry": 
              {
                "type": "Point","coordinates": [ 40.814, 15.845, 1]
              } 
           },

         ]
     }
mapdata2 = {
  "type": "FeatureCollection",
  "features" : []
};

mapdata2.features = data.features
console.log(mapdata2);

Guillaume Adam · Accepted Answer · 2019-09-03 12:39:49Z

2

It seems you want to copy the object. You can simply do as below.

var mapdata2 = JSON.parse(JSON.stringify(data));

By the way, you got error "TypeError: i.features is undefined" because i is a string representing a key of the object. It will take the values "type" and "features".

To loop over the items in the array data.features, you should do:

for (var i=0;i<data.features.length;i++) {
  var item = data.features[i];
}

answered Sep 3, 2019 at 12:39

Guillaume Adam

3013 silver badges10 bronze badges

Comments

Marcos Luis Delgado · Accepted Answer · 2019-09-03 12:46:23Z

There are some errors here:

in keyword in a for bucle iterates over keys, not values, which is what I understand you want to do to copy your data.
you are trying to access property properties of the array features without accessing an index of that array first.

Changing the last part of your code to:

for(const feature of data.features){
    mapdata2.features.push({
        type:"Feature",
        properties : { title: feature.properties.title, startDate: feature.properties.startDate, endDate: feature.properties.endDate, latitude: feature.properties.latitude, longitude: feature.properties.longitude, content: feature.properties.content },
        geometry : { type: "Point", coordinates: feature.geometry.coordinates }
    })
}
console.log(mapdata2);

should do the job :)

However, if you are just intending to copy the data I would recommend:

mapdata2 = {...data}
console.log(mapdata2)

Gabriele Magno · Accepted Answer · 2019-09-03 12:43:14Z

a 'quick fix' maintaining your style:

for(i of data.features) {
  console.log(i)
    mapdata2.features.push({
        type:"Feature",
        properties : { 
            title: i.properties.title, 
            startDate: i.properties.startDate, 
            endDate: i.properties.endDate, 
            id: i.properties.id, 
            latitude: i.properties.latitude, 
            longitude: i.properties.longitude, 
            content: i.properties.content },
        geometry : { 
            type: "Point",  
            coordinates: i.geometry.coordinates 
        }
    })
}

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