How to reformat JSON in rails -

i trying out d3.js rails app give me pretty graphs. 1 of graphs trying out forced directed graph. in order create json needs in format

{   "nodes":[     {"name":"myriel"},     {"name":"napoleon"},     {"name":"mlle.baptistine"},     {"name":"mme.magloire"}  ], "links":[     {"source":1,"target":0,"value":1},     {"source":2,"target":0,"value":8},     {"source":3,"target":0,"value":10},     {"source":3,"target":2,"value":6} ] } 

i have produced json database using query:

 user.joins("inner join relationships on users.id = relationships.user_id").select(" users.name, relationships.source, relationships.target,relationships.value") 

which created in controller follows

 def index        render :json =>  user.joins("inner join relationships on users.id = relationships.user_id").select(" users.name, relationships.source, relationships.target,relationships.value")   end end 

and result looks this:

[{"name":"myriel","source":121,"target":1,"value":1},{"name":"napoleon","source":119,"target":2,"value":2},    {"name":"myriel","source":121,"target":1,"value":2},{"name":"myriel","source":121,"target":3,"value":1},{"name":"mlle.baptistine","source":122,"target":2,"value":3}] 

is there simple way map json need?

as suggested in answer, create class method:

class user   def self.including_relationships     user.joins("inner join relationships on users.id = relationships.user_id").select("users.name, relationships.user_id, relationships.target,relationships.value").each_with_object(hash.new{|h, k| h[k] = []}) |a, obj|        obj['nodes'] << a.slice('name')       obj['links'] << a.slice('source', 'target', 'value')     end   end end 

then in controller:

def index   render :json =>  user.including_relationships end 

i named method including_relationships since not creating json instead converting data hash object, can name wish.