Second Order Relationship in Graph Database

Question

I'm creating an app which is quite relationship heavy. One of the features of the site is a recommendation feature, where users can rate things for others. For this, it seems like a Graph DB would be ideal so I am planning on using Neo4j, alongside Ruby.

This all seems fairly straight forward, however I would like to include a feature where users can rate a specific relationship. For example, a user could recommend a hotdog in a specific restaurant, etc. The only way I can really think about doing this with a Graph DB is to either add a 'joining node' between the two nodes, connecting all three, or by adding lists of properties to the relationship (ie adding hotdog_5 to the user-restaurant relationship). Obviously the rating could just be added to the hotdog-restaurant relationship, but you wouldn't be able to trace the users that rated it, to prevent them rating more than once.

Any thoughts on the problem would be appreciated.

Answer 1

You may want to retrieve all the comments from a user, or the comments about hotdogs in all restaurant, or all the comments about all type of food in a restaurant so I would recommend to do it like :

1. user-[:write]->comment
2. comment-[:about]->hotdog
3. comment-[:concern]->restaurant
4.restaurant-[serve]->hotdog 

Not sure about the last one it may be useless due to 2 and 3, it depend a lot on the queries you'll run