Updating single field of a model

I have model with multiple fields. The model in the Python App Engine app looks like this:

class Team(ndb.Model):
  field_a = ndb.StringProperty()
  field_b = ndb.StringProperty()
  field_c = ndb.IntegerProperty()

When running this code from the Node.js part of the app:

var key = ds.key(['Team', team_id]);
    ds.update({
      key: key,
      data: [{name: "field_c", value: new_count, excludeFromIndexes: true}]
    }, function(err) {
      if (!err) {
        // Record saved successfully.
      }
    });

I get fields field_a and field_b deleted from the model. How can I update only one field of the object without deleting the other fields?

Thanks

You have to do a manual "get and update", which would look like:

var key = ds.key(['Team', team_id]);

ds.get(key, function(err, entity) {
  if (err) {
    // Error handling omitted.
  }

  entity.data.field_c = newCount;

  ds.save({
    key: key,
    data: entity.data
  }, function(err) {
    if (!err) {
      // Record saved successfully.
    }
  });
});

Thanks, that solved the overwriting issues, but it doesn't work with ComputedProperty. Any ideas how to make that work too?

@MeLight

@MeLight Did you try to fetch the data after doing a save? Per the upstream docs it looks like the stored value is ignored and they re-compute the property when you next read from Datastore.