Create GeoJson from coordinates array in the same Mongodb collection - node.js

Question

I want to modify my mongodb collection from 2d to 2dsphere.
I have this structure in my db.users:
{
"_id" : "1c6930387123e960eecd65e8ade28488",
"interests" : [
{
"_id" : ObjectId("56a8b2a72f2c2a4c0250e896"),
"coordinates" : [-3.6833, 40.4]
}
],
}
I would like to have something like this:
{
"_id" : "1c6930387123e960eecd65e8ade28488",
"interests" : [
{
"_id" : ObjectId("56a8b2a72f2c2a4c0250e896"),
"loc":{
"type":"Point",
"coordinates" : [-3.6833, 40.4]
}
}
],
}
I tried this:
db.users.update( {interests:{$elemMatch:{coordinates : { $exists: true } }}}, { $set: { 'interests.$.place':{"type":"Point", "coordinates":'interests.$.coordinates'} } }, { upsert: false, multi: false });
Obviously, it insert literally "'interests.$.coordinates'
And tried this in Node:
users.find({interests:{$elemMatch:
{coordinates :
{ $exists: true } }}} ,
{"interests.coordinates":1,"interests._id":1,"_id":0 }).forEach( function( doc ){
users.update( {interests:
{$elemMatch:
{_id : doc.interests[0]['_id'] }}},
{ $set: { 'interests.$.loc':{"type":"Point", "coordinates":doc.interests[0]['coordinates']} } },
{ upsert: false, multi: false },function(err, numberAffected, rawResponse) {
var modified=numberAffected.result.nModified;
console.log(modified)
});
});
But coordinates were inserted with mixed values.
Thoughts?
Thanks!!

Answer 1

I didn't test this piece of code but I think this would shed light on this issue.
users.find(
{interests:{ $elemMatch: {coordinates : { $exists: true } }}}).forEach( function( doc ){
for(var c = 0; c < doc.interests.length; c++) {
var orig = doc.interests[c].coordinates;
doc.interests[c].loc: { type:"Point", coordinates: orig };
//delete doc.interests[c].coordinates;
};
users.update({ _id: doc._id }, doc);
});
Try to iterate over all documents in your collection modifying the whole document and then update it in a single line.
Warning: If you have a huge quantity of documents in your collection that match the 'find' condition, you should use pagination (skip/limit) to avoid performance and memory issues in the first load.