Attributes of an Object

There is function of attributes_name in Active record by which I can check the keys of an object but I can check the blank keys for of an object which is of MongoID not of ActiveRecord, When I try t开发者_开发百科his I got the following response

ruby-1.9.2-p290 :001 > u = User.new
=> #<User _id: 4e684f7771393161cc000001, _type: nil, username: nil, first_name: nil, last_name: nil, email: nil, password: nil, password_salt: nil, password_hash: nil, profile_picture: nil, facebook_id: nil, facebook_enabled: nil, facebook_access_token: nil, twitter_id: nil, twitter_enabled: nil, twitter_access_token: nil, twitter_access_secret: nil, points: nil, remember_token: nil, remember_token_expires_at: nil, active: false, activation_code: nil, activated_at: nil> 
ruby-1.9.2-p290 :002 > u.attributes.keys
=> ["active", "_id"] 

It only show the attributes which are not nill , How can I check all the attributes even which are nil ? I actually wanted to make function which needs to use user.attributes.keys.include?('name')

Probably you want fields. Attributes is more or less related to what you got from db, fields is what you defined in your model. Following works for me:

User.fields.keys
User.first.fields.keys

User.attributes.keys

worked with me but you can try columns

User.columns.map(&:name)

To get the keys in the same order as the columns in the db I used this on Rails 3.2 Ruby 1.8.7:

User.content_columns.collect{|c| c.send(:name)}

my particular use was achieved from a variable with an array of objects

@objects.first.class.content_columns.collect{|c| c.send(:name)}