扶手：方法与模型链接 [英] Rails: method chaining in model

问题描述

试图建立在我的模型搜索方法，并加入基于参数传递给方法的条件。然而，没有得到最初的里后链接

Trying to create a search method in my model and join conditions based on arguments passed to the method. However, nothing gets chained after the initial "where"

控制器：

Item.search(args)

型号：

  def self.search(args = {})
    include ActsAsTaggableOn # Tagging model for search

    result = where("title LIKE ? OR description LIKE ? OR tags.name LIKE ?", "%#{args[:search]}%", "%#{args[:search]}%", "%#{args[:search]}%")
      .joins("JOIN taggings ON taggings.taggable_id = items.id")
      .joins("JOIN tags ON taggings.tag_id = tags.id")

      # Categories
      if args[:categories]
        result.where(:category_id => args[:categories])
      end

      # Order
      if args[:order] == "category"
       result.joins(:categories).order("categories.title ASC")
      else
        result.order("title DESC")
      end


      # Pagination
      result.paginate(:per_page => 10, :page => args[:page])

end

即使我去掉了，如果块，做一个链条直接算账，这是行不通的：

Even if I strip out the if block and do a chain directly afterwards, it doesn't work:

result = where(:foo => "bar")
result.order("name DESC")

...只是运行在那里。

... runs just the where.

任何想法？

感谢提前。

推荐答案

你应该做的是IT连锁通过调整结果的定义，当您去：

What you should do is chain it by adjusting the definition of result as you go:

result = result.where(...)

每次必须重新分配回产生与更新的范围。这是因为 result.where 返回一个新的范围，它不会调整现有的范围。

Each time you must re-assign back to result with the updated scope. This is because result.where returns a new scope, it does not adjust the existing scope.

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