Updating multiple documents on nested object change - ruby-on-rails

Question

I am using the elasticsearch-rails and elasticsearch-model gems for my Ruby on Rails app, which is like a question-and-answer site.
My main question is: how do you tell Elasticsearch which documents to update when there was a change to a nested object that's nested in multiple documents?
I have one index my_index and mappings for question, and answer. In particular, question has a nested object with a user:
"question": {
"properties": {
"user": {
"type": "nested",
"properties": {
"created_at": {
"type": "date",
"format": "dateOptionalTime"
},
"name": {
"type": "string"
},
"id": {
"type": "long"
},
"email": {
"type": "string"
}
}
}
...
}
}
It's possible for a user to change his name, and I have hooks to update the user in Elasticsearch:
after_commit lambda { __elasticsearch__.index_document}, on: :update
But this isn't updating the appropriate question objects correctly, and I don't know what to pass to the index_document call to make sure it updates all the corresponding questions with the new user name. Does anyone know? It might even help me to see what a RESTful/curl request should look like?
Any help would be appreciated!

Answer 1

There are a couple of different ways you can go about this. They are all probably going to require some code changes, though. I don't think there is a way to do what you are asking directly, with your current setup.
You can read about the various options here. If you can set things up as a one-to-many relationship, then the parent/child relationship is probably the way to go. Then you could set up something like this:
PUT my_index
{
"mappings": {
"user": {
"properties": {...}
},
"question": {
"_parent": {
"type": "user"
},
"properties": {...}
}
}
}
And in that case you would be able to update users independently of questions. But it makes querying more complicated, which may or may not be a problem in your application code.
Given that you already have nested documents set up, you could simply query for all the documents that have that particular user as a nested document, with something like:
POST /test_index/question/_search
{
"filter": {
"nested": {
"path": "user",
"filter": {
"term": {
"user.id": 2
}
}
}
}
}
and once you have all the affected question documents you can modify the user name in each one and update all the documents with a bulk index request.
Here is some code I used to play around with that last bit:
http://sense.qbox.io/gist/d2a319c6b4e7da0d5ff910b4118549228d90cba0