我有几个复杂的 SQL,需要将其转换为 ActiveRecord 查询。请帮助我:
我的模型:
class Product < ActiveRecord::Base
belongs_to :watch, :counter_cache => true
end
class Watch < ActiveRecord::Base
belongs_to :category
has_many :products
end
class Category < ActiveRecord::Base
has_ancestry :cache_depth => true, :depth_cache_column => :depth
has_many :watches, :dependent => :destroy
has_many :products, :through => :watches
end
所以类别有两层深度的祖先,根是 make,子级是 serie。 我的 SQL 如下:
scope :by_make, lambda { |make_name| Product.find_by_sql("
SELECT p.* FROM products p INNER JOIN watches w ON p.watch_id = w.id
INNER JOIN categories series ON w.category_id = series.id
INNER JOIN categories makes ON series.ancestry = makes.id
WHERE makes.name LIKE '%#{make_name}%'
") unless make_name.blank? }
scope :by_series, lambda { |series_name| Product.find_by_sql("
SELECT p.* FROM products p INNER JOIN watches w ON p.watch_id = w.id
INNER JOIN categories series ON w.category_id = series.id
WHERE series.name LIKE '%#{series_name}%'
") unless series_name.blank? }
请帮助将它们转换为 ActiveRecord 查询,因为不要在查询末尾获取数组非常重要,谢谢!
最佳答案
最简单的解决方案就是在 find_by_sql
的开头添加 where
过滤器,如下所示:
scope :by_make, lambda { |make_name| where(:watch_id => Watch.find_by_sql("
SELECT w.* FROM watches w
INNER JOIN categories series ON w.category_id = series.id
INNER JOIN categories makes ON series.ancestry = makes.id
WHERE makes.name LIKE '%#{make_name}%'
")) unless make_name.blank? }
scope :by_series, lambda { |series_name| where(:watch_id => Watch.find_by_sql("
SELECT w.* FROM watches w
INNER JOIN categories series ON w.category_id = series.id
WHERE series.name LIKE '%#{series_name}%'
")) unless series_name.blank? }
应返回 AR 集合。
关于mysql - Rails 复杂 SQL,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/7093727/