activerecord json output not showing relationship in output

Question

I've got a posts model and of course authors which is a foreign key relationship to my users.

I am trying to output in JSON, the posts with the authors names. I know this is rails 101, but I can't call post.author because I'm not in a view.

I've tried doing this a few ways, but none seem to be working.

My post model has

 belongs_to :user, :foreign_key => :author_id

def post_author
 self.each {|a| a['author'] = User.find(a.id)}
end

in my controller I've tried all sorts of

posts=Post.find(:all).includes(:user)

#or
posts=Post.find(:all).includes(:post_author) #don't think this is right anyway, but tried 

#and 
posts = Post.find(:all)
posts = JSON::Parse(posts.to_json()).merge('author'=>posts.author) #or posts.user, etc etc

of course, none of these have worked, which is why I'm posting here. What's the best way to get the author of a post.

----------------------update ---------------------------

@rjz provided a response which works, but I'm hoping isn't the best way. He suggested using

posts.to_json(:include=> :user,:only[:username])

this meant I was only getting the username back, but I need more than that so I started using :except instead. The problem here is that I've got a fields like id which I need in the post, but not in the author, but if I exclude them in this manner, the field is excluded from the results completely. I'm also having to list out each field I need, and I'm not sure if that is the best way.

rjz · Accepted Answer · 2012-03-19 18:16:32Z

1

You might have to tease the name of your association a bit to get exactly what you want, but what you're looking for is the :include option when you serialize with to_json:

posts.to_json(:include => :user)

answered Mar 19, 2012 at 18:16

rjz

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3 Comments

pedalpete Over a year ago

that gets me the user @rjz, but brings up the new problem of now returning everything, including email, etc. I tried posts.to_json(:include => :user, :select => :username), but that didn't work. can I mix a select in with this?

rjz Over a year ago

Not exactly, but you can use the :only option in to_json to limit what fields get serialized. It's detailed in the documentation I linked above.

pedalpete Over a year ago

Thanks rjz, this is an ok, solution. I'm using :except for now, but I'm having to either remove or add all the fields for both tables. I'm hoping there may be a better way, and I'll update the question. If there isn't a better response, the answer is yours. thanks again

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