Im building an ad-system where users can dynamically create 'fields' for each ad type.

My models and example values:

AdType:  
| id | name  
|----|-----  
| 1  | Hotel  
| 2  | Apartment  

AdOption:  
| id | ad_type_id | name  
|----|------------|-----
| 1  | 1          | Star rating  
| 2  | 1          | Breakfast included?  
| 3  | 2          | Number of rooms  

AdValue: (Example after saving)  
| id | ad_id | ad_option_id  | value  
|----|-------|---------------|------  
| 1  | 1     | 1 (stars)     | 5  
| 2  | 1     | 2 (breakfast) | true  

Ad: (Example after saving)  
| id | description     | etc....  
|----|-----------------|--------  
| 1  | very nice hotel | .......  

So lets say I want to create a new ad, and I choose Hotel as the ad type. Then I need my view to dynamically create fields like this: (I'm guessing?)

[Label] Star rating:  
[hidden_field :ad_id] [hidden_field :ad_option_id] [text_field :value]  

[Label] Breakfast included?  
[hidden_field :ad_id] [hidden_field :ad_option_id] [text_field :value]

And also, how to save the values when the ad record is saved

I hope this is understandable. If not just ask and I'll try to clarify.