Rails：基于多个参数的过滤器？

Question

我有一个简单的应用程序，用户可以根据三个不同的参数按类别、学科和目标群体进行过滤。所有参数都是可选的。到目前为止它可以工作，但下面的控制器有点臃肿，我也认为三个 if 语句有点混乱。

有没有更清洁的方法来做到这一点？

def index
@listings = Listing.includes(:categorizations, :listing_disciplines, :listing_targets).page(params[:page])

if params[:category_id].present? && params[:category_id] != ""
  @category_id = Category.find_by(id: params[:category_id])
  @listings = @category_id.listings
end

if params[:discipline_id].present? && params[:discipline_id] != ""
  @discipline_id = Discipline.find_by(id: params[:discipline_id])
  @listings = @discipline_id.listings
end

if params[:target_id].present? && params[:target_id] != ""
  @target_id = Target.find_by(id: params[:target_id])
  @listings = @target_id.listings 
end

if params.blank?
  @listings   
end

这是我的列表模型：

class Listing < ActiveRecord::Base
  has_many :categorizations, dependent: :destroy
  has_many :categories, through: :categorizations

  has_many :listing_disciplines, dependent: :destroy
  has_many :disciplines, through: :listing_disciplines

  has_many :listing_targets, dependent: :destroy
  has_many :targets, through: :listing_targets

  has_attached_file :image, styles: { :medium => "200x200#" }
  validates_attachment_content_type :image, content_type: /\Aimage\/.*\Z/

  validates :title, presence: true, uniqueness: true

  paginates_per 15

end

Answer 1

我不确定您的代码是否有效，因为您正在重置每个 param 的列表。我假设您希望能够同时过滤所有三个。更清洁的方法是：

def index
  @listings = Listing.joins(:categorizations, :listing_disciplines, :listing_targets)
  @listings = @listings.where("categorizations.category_id = ?", params[:category_id]) if params[:category_id].present? && params[:category_id] != ""
  @listings = @listings.where("listings_disciplines.discipline_id = ?", params[:discipline_id]) if params[:discipline_id].present? && params[:discipline_id] != ""
  @listings = @listings.where("listing_targets.target_id = ?", params[:target_id]) if params[:target_id].present? && params[:target_id] != ""
  @listings = @listings.page(params[:page])
end

这将使所有过滤器累积。