ActiveRecord的动态查找方法链接基于PARAMS [英] Dynamic ActiveRecord finder methods chaining based on params

问题描述

林新轨道，我想根据不同势GET参数（筛选和排序）做出选择查询。可我一些如何添加条件来查找code？

Im new to rails and I want to make a select query based on diffrent GET params (filtering and sorting). Can I some how add conditions to find in the code?

例如：

if params[:ratings] 
  Movie.where(:rating => params[:ratings].keys)
end

然后添加顺序等有条件的地方。我怎样才能achive呢？也许有更好的方法来dybamicly修改选择查询（未做SQL字符串）。 谢谢你。

and then add ordering and other where conditions. How can I achive this? Maybe there is a better way to dybamicly modify select query (without making SQL string). Thanks.

推荐答案

在其中，，序，.. 。方法返回的ActiveRecord ::关联对象，这样你就可以不停的叫唤更多的查询方法：

The where, order, ... methods return ActiveRecord::Relation objects so you can keep calling more query methods:

query = Movie
if(params[:ratings])
  query = query.where(:rating => params[:ratings].keys)
end
if(params[:some_order_param])
  query = query.order(params[:some_order_param])
end
# Keep adding more 'where', 'order', 'group', ... methods as needed ...
results = query.all

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