finder_sql不解析字符串使用Rails [英] finder_sql does not parse string with Rails

问题描述

我有一个查询我使用的问题 finder_sql 不正确地分析它交给了前向PostgreSQL导致数据库语法错误。

I have the problem that the query I use for finder_sql is not parsed correctly before it is handed over to PostgreSQL resulting in a database syntax error.

为了说明我刚才用的例子code从这里的问题：

To illustrate the problem I just used the example code from here:

的http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

我只改将class_name 到用户，因为我没有一个人的模型，但是这并不事情在这里。

I only changed class_name to "User" as I don't have a person model but this does not matter here.

has_many :subscribers, :class_name => "User", :finder_sql =>
'SELECT DISTINCT people.* ' +
'FROM people p, post_subscriptions ps ' +
'WHERE ps.post_id = #{id} AND ps.person_id = p.id ' +
'ORDER BY p.first_name'

当我用这个，我得到以下错误：

When I use this, I get the following error:

User Load (0.3ms)  SELECT DISTINCT people.* FROM people p, post_subscriptions ps WHERE
ps.post_id = #{id} AND ps.person_id = p.id ORDER BY p.first_name
PGError: ERROR:  Syntaxerror near »{« 
LINE 1: ...ople p, post_subscriptions ps WHERE ps.post_id = #{id} AND p...
                                                         ^

正如你可以看到＃{ID} 不与随后引发的PostgreSQL错误的对象的ID代替。

As you can see #{id} is not replaced with the id of the object which then raises the PostgreSQL error.

环保

• 的Rails 3.1
• RVM
• 的PostgreSQL 9.1
• 的Ubuntu 11.10
• 红宝石1.9.2p290（2011-07-09改版32553）的x86_64-linux的]

推荐答案

我想你实际上是在寻找的是这样的：

I think what you're actually looking for is this:

has_many :posts, :finder_sql =>
    proc {"SELECT p.* from posts p join topics t on p.topic_id = t.id where t.id=#{id}"}

由于Rails的3.1，你必须使用一个字符串的一个进程，而不是使用像田＃{ID} 。

请参阅这里的问题： https://github.com/rails/rails/issues/3920

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