这是为什么ActiveRecord的声明服务器而不是控制台失败 [英] Why is this ActiveRecord statement failing in Server but not Console

问题描述

我有以下的查询，它失败在轨道小号在一个特定的控制器。这不是失败在轨ç。

I have the following query which is failing in rails s in a particular controller. It's not failing in rails c.

Post.includes(:user).find(:all, :limit => 10, :order => 'users.display_name ASC')

在控制台返回正确的数据。在服务器中，我得到这个错误

In the console it returns the correct data. In the server, I get this error

ActiveRecord::StatementInvalid: PGError: ERROR:  column posts.users.display_name does not exist
LINE 1: ...s_count" AS t0_r7, "posts"."popularity" AS t0_r8, "posts"."u...
                                                             ^

查询是漫长的，我就包括一些相关片段

The query is long and I'll just include a few relevant snippets

: SELECT  "posts"."id" AS t0_r0, "posts"."post_content" AS t0_r1, 
...    
"posts"."popularity" AS t0_r8, "posts"."users.display_name" AS t0_r9,
"posts"."subtopics.name" AS t0_r10, "posts"."categories.category_name" 
AS t0_r11
...
FROM "posts" LEFT OUTER JOIN "users" ON "users"."id" = "posts"."user_id" 
ORDER BY users.display_name ASC LIMIT 10

在控制器中，查询生成3个额外的条款。查询标签他们作为t0_r9，t0_r10和t0_r11。这似乎是AR的增加，是因为我引用这些特定的列在该控制器操作的视图。我不明白为什么它会做到这一点，虽然，因为这是使用包括。

In the controller, the query generates 3 extra terms. The query labels them as t0_r9, t0_r10, and t0_r11. It seems like AR is adding this because I'm referencing those specific columns in the view of that controller action. I don't see why it'd do that, though, as that's the purpose of using includes.

推荐答案

因此​​，错误不是在code我张贴。我有一个助手来确定命令的列。它看起来是这样的：

So the error wasn't in the code I posted. I had a helper to determine which column to order by. It looked something like this:

valid_names = Post.column_names
valid_names = valid_names.concat(["users.display_name", "subtopics.name",
  "categories.category_name"])

valid_names.include?(params[:sort]) ? params[:sort] : "popularity"

我一点也不知道，这实际上将串联额外的条件到 Post.column_names 。我通过做副本 Post.column_names.clone 修复了这个问题，这解决了问题。

Little did I know that this would actually concatenate the extra terms onto Post.column_names. I fixed this issue by making a copy with Post.column_names.clone and this resolved the issue.

我觉得pretty的愚蠢犯这种错误，但希望这会帮助别人谁是运行到了同样的问题。

I feel pretty silly making this mistake, but hopefully this will help someone else who's running into the same issue.

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