How to model linked accounts like this in MongoDb? - mongodb

Question

My application has both facebook and twitter users. Now users can merge two accounts together which means they can login with either facebook or twitter account.
Right now, I have a model like this.
{ "_id" : ObjectId("51103a3e69931d2f03000001"), "email" : "email", "id" : "twitter_id", "token" : "token", "secret" : "secret"}
{ "_id" : ObjectId("51103a3e69931d2f03000001"), "email" : "email", "id" : "facebook_id", "token" : "token", "secret" : ""}
Now if these two accounts are the same and the user decided to merge or connect one of his account to something else. How should I change this model effectively and performance as well. I am thinking of having another object called
{"linked_ids" : ["facebook_id", "linkedin_id" ]}
in both accounts. So, the data would be like this. Once merged.
{ "_id" : ObjectId("51103a3e69931d2f03000001"), "email" : "email", "id" : "twitter_id", "token" : "token", "secret" : "secret", "linked_id" : ["facebook_id"] }
{ "_id" : ObjectId("51103a3e69931d2f03000001"), "email" : "email", "id" : "facebook_id", "token" : "token", "secret" : "", "linked_id" : ["twitter_id"] }
Not sure if this would be the best way for performance and scalability?

Answer 1

Why not have one user document in a user collection from the start? You could model it this way instead:
{
"_id" : ObjectId("..."),
"username" : "bob123",
"accounts" : [
{
"email": "email",
"id": "twitter_id",
"token": "token",
"secret": "secret",
"type" : "Twitter"
},
{
"email": "email",
"id": "facebook_id",
"token": "token",
"secret": "",
"type" : "Facebook"
}
]
}
Mongo has plenty of operations to deal with arrays. You can add to them, update one item in the array only, etc.
Doing joins with Mongo introduces complexity that it isn't good at handling as of now. You'd have to do that "join" in your application.
Also this model means you can add any other forms of authentication in one document.