Rails 3.2 weird views

First time I ask a question on this site, hope you can help me for my 'problem'. :-)

Actually, it's not really a problem in development, but in production...

Here's my problem:

I'm working with Rails 3.2.11 and ruby 2.1.7. For this, I'm using RubyMine. Since the beginning, when I push some data in a hash, the record appears also in JSON.

I searched in my configuration, in my development.rb, initializers,... But I don't know where it comes! :-(

Because I don't have any reputation on this site, I can't show you what it is, so I will explain it in other way.

I add my User 'Test1' to a tournament via the view. When it is added, this appears also in the view:

[#<User id: 29, country: "BE", nb_victory: nil, nb_defeat: nil, total_points: nil, created_at: "2016-02-16 14:20:36", updated_at: "2016-02-18 10:07:49", first_name: "T", last_name: "T", pseudo: "Test1", email: "test1@test.com", encrypted_password: "$2a$10$WRHkX0mN0t1GAEYg8CQPJeVHBg0bVzBmDxpHKtU.g23A...", reset_password_token: nil, reset_password_sent_at: nil, remember_created_at: nil, sign_in_count: 3, current_sign_in_at: "2016-02-18 10:07:49", last_sign_in_at: "2016-02-17 09:31:06", current_sign_in_ip: "127.0.0.1", last_sign_in_ip: "127.0.0.1", confirmation_token: "Q2rJ8aWYPmttd9XRjKgX", confirmed_at: nil, confirmation_sent_at: "2016-02-16 14:20:36", unconfirmed_email: nil, avatar: "chat.png", provider: nil, uid: nil, role: "player">] 

What's wrong with it? It seems a configuration problem.