ruby on rails - Handling multiple filters (params) cleanly in controller -

i have class called post, , need able accommodate following scenarios:

• if user selects category, show posts category
• if user selects type, show posts type
• if user selects category , type, show posts category type
• if user selects nothing, show posts

i'm wondering if it's inevitable controller going gross ton of conditionals... here's flawed approach @ tackling – know how can accomplish this?

class postscontroller < applicationcontroller    def index     @user = current_user      # if user has not specified type or category,      # show them     @posts = post.all      # if user has selected category, no type,      # show posts category.     if params[:category] && !params[:type]       category = category.find(params[:category])       @posts = @category.posts     end      # if user has selected category , type, show     # posts category type     if params[:category] && params[:type]       category = category.find(params[:category])       type = params[:type]       @posts = category.posts.where(post_type: type)     end      # if user has selected type not category, show      # of posts type      if params[:type] && !params[:category]       type = params[:type]       @posts = post.where(post_type: post_type)     end   end  end 

you'll better off following convention of "fat models, skinny controllers", meaning should put kind of logic in model itself. post class should able report posts correspond conditions, can define method that:

class post < activerecord::base   ...   def self.by_category_and_type(category = nil, type = nil)     return where(category: category, type: type) if category && type     return where(category: category) if category     return where(type: type) if type       end   ... end 

then in controller can call

@posts = post.by_category_and_type(params[:category], params[:type])

i haven't tested this, think should trick. let me know if doesn't!