Programmatically updating fields in Mongo and Meteor

Question

I have a collection that I'd like to update. The field is given programmatically, so I'd like to do something like this:

var update_string = 'coordinates.lat';
var update = function(value, id, update_string) {
  Collection.update({_id:id}, {$set:{update_string:value}})
}  

That however does not work and just sets "update_string" to have value {{value}} in the object with _id {{id}} in the Collection. I also tried doing var update_string = "'coordinates.lat'"; to no avail.

How do I accomplish this? Thanks.

Answer 1

You need to set the key in your update $set parameter correctly:

var update = function(value, id, update_string) {
   var update_query = {};
   update_query[update_string] = value 
   Collection.update({_id:id}, {$set:update_query})
}  

Basically without the modification above, If you used {update_string:value} you would be setting the value of update_string, not coordinates.lat.