First the structure of my documents:

{
  "_id": "541a8bea74123744b371d38e",
  "geometry": {
    "type": "Point",
    "coordinates": [
      5.3435,
      51.69554
    ]
  },
  "type": "Feature",
  "properties": {
  }
}

The thing is I want to add a field using the update function in a forEach loop. The loop works, I can iterate over every document in the collection but the update function does nothing. This is what I have:

var counter = 0;
collection.find({}, {
    stream: true
  })
  .each(function(doc) {
    counter++;
    var hash = geohash.encode(doc.geometry.coordinates[1], doc.geometry.coordinates[0], precision = 9);
    console.log("id: " + doc._id + " hash: " + hash + " counter= " + counter);
    collection.update({
        _id: doc._id
      }, {
        $set: {
          "properties.geohash.precision9": hash
        }
      },
      function(err) {
        if (err) console.log(err);
      }
    );
  })
  .error(function(err) {
    // handle error
    console.log(err);
  })
  .success(function(doc) {
    // final callback
    console.log("added geohash");
    res.send({
      objects: doc
    });
  });

Where am I wrong?

First the structure of my documents:

{
  "_id": "541a8bea74123744b371d38e",
  "geometry": {
    "type": "Point",
    "coordinates": [
      5.3435,
      51.69554
    ]
  },
  "type": "Feature",
  "properties": {
  }
}

The thing is I want to add a field using the update function in a forEach loop. The loop works, I can iterate over every document in the collection but the update function does nothing. This is what I have:

var counter = 0;
collection.find({}, {
    stream: true
  })
  .each(function(doc) {
    counter++;
    var hash = geohash.encode(doc.geometry.coordinates[1], doc.geometry.coordinates[0], precision = 9);
    console.log("id: " + doc._id + " hash: " + hash + " counter= " + counter);
    collection.update({
        _id: doc._id
      }, {
        $set: {
          "properties.geohash.precision9": hash
        }
      },
      function(err) {
        if (err) console.log(err);
      }
    );
  })
  .error(function(err) {
    // handle error
    console.log(err);
  })
  .success(function(doc) {
    // final callback
    console.log("added geohash");
    res.send({
      objects: doc
    });
  });

Where am I wrong?

• javascript
• mongodb
• monk

2 Answers 2

A working code in MongoDb shell

db.collection.find().forEach(function(item)
{
    var hash = ....;
    item.properties.geohash.precision9 = hash;
    db.collection.save(item);
})

I believe with some small changes u can use it with monk

I believe your issue is with your chosen schema. Properties is a subdocument and items stored in it are accessible with the '.', but then you're attempting to set a property of another subdocument geohash. Monk is a very lightweight MongoDB driver and will not support this many levels of subdocuments. I suggest changing your schema to the following:

{
  "_id": "541a8bea74123744b371d38e",
  "geometry": {
   "type": "Point",
   "coordinates": [
     5.3435,
     51.69554
   ]
 },
 "type": "Feature",
 "properties": {
 },
"geohash": {
  "precision9": "somevalue"
 }
}

I would try to flatten out the document structure by eliminating subdocuments. In my opinion having a subdocument called properties is redundant because information about the current document pertains directly at the parent level. Unless I am miss understanding something about your data. If that is the case, please provide more documents stored in your database particularly ones that have values for percision9 or other 3 deep properties.

One thing you might be able to do, although a bit ugly, is to use an additional variable to build the subdocument and assign the value 'hash' and then set properties equal to that new variable. This would overwrite anything previously stored in properties unless you handled it properly:

var newProperties = {
 geohash: {
  presision9: hash
 }
}

collection.update({
        _id: doc._id
      }, {
        $set: {
          "properties": newProperties
        }
      },
      function(err) {
        if (err) console.log(err);
      }
    );
  })