add to existing object in json array Rails 3 - json

Question

render :json mailbox.inbox.as_json(:include => [
{:messages => {:only => [:body]}},
{:recipients => {:only => [:Firstname,:Surname]}}
])
produces the following output from my Rails controller:
[
{
"conversation":
{
"subject":"Subject for conversation 2",
"messages" :[
{"body":"Message 1"},
{"body":"Message 2"}
],
"recipients": [
{"Firstname":"James","Surname":"Smith"},
{"Firstname":"John","Surname":"Doe"}
]
}
}
]
What I would like to do is to add a current_user key:value pair to each conversation object so the out sample would look like this:
[
{
"conversation":
{
"subject":"Subject for conversation 2",
"messages" :[
{"body":"Message 1"},
{"body":"Message 2"},
],
"recipients": [
{"Firstname":"James","Surname":"Smith"},
{"Firstname":"John","Surname":"Doe"}
],
"current_user" :[
{"id":10}
]
}
}
]
I don't have access to the conversation model in question (it's running off the mailboxer gem) so can't override as_json. Any help would be appreciated

Answer 1

So, formalizing the comments.
By looking the apidock of json_as, you can see that the only way to include arbitrary data is to add a method that retunrs the data you want to use in the model.
Since it is not the best thing to do in many ways and you don't have access to the model, one way out to customize your json is using a popular gem called jbuilder, that allows you to create a more complex json.