Rails的2.3:如何把这个SQL语句转换成一个named_scope [英] Rails 2.3: How to turn this SQL statement into a named_scope
本文介绍了Rails的2.3:如何把这个SQL语句转换成一个named_scope的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
有一点困难,搞清楚如何从这个SQL查询创建named_scope:
SELECT *从foo其中ID NOT IN(选择foo_id从巴),foo.category =? ORDER BY RAND()LIMIT 1;
范畴应变量发生变化。
什么是named_scope可以为问题待写入的最有效的方式以上?
解决方案
named_scope:SCOPE_NAME,拉姆达{|类别|
{
:条件=> [ID NOT IN(选择foo_id从巴),foo.category =?,类别】,
:为了=> RAND(),
:上限=> 1
}
}
Having a bit of difficulty figuring out how to create a named_scope from this SQL query:
select * from foo where id NOT IN (select foo_id from bar) AND foo.category = ? ORDER BY RAND() LIMIT 1;
Category should be variable to change.
What's the most efficient way the named_scope can be written for the problem above?
解决方案
named_scope :scope_name, lambda { |category|
{
:conditions => ["id NOT IN (select foo_id from bar) AND foo.category = ?", category],
:order => 'RAND()',
:limit => 1
}
}
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