如何在运行时更改ActiveRecord的表名 [英] How to change ActiveRecord's table name during runtime

问题描述

我正在运行Rails应用程序时更改 table_name_prefix (可能听起来很奇怪，但这确实是我想要的).当 table_name_prefix 更改为 ActiveRecord 时，我通过调用重置表名( table_name 和 quoted_table_name )reset_table_name ，并且它们会更改..但是我还有另一个问题.

I am changing the table_name_prefix during running of a rails application (might sound weird, but really that's what I want). When the table_name_prefix changes for the ActiveRecord I reset the table names (table_name and quoted_table_name) by calling reset_table_name, and they change.. however I have another issue.

如果表名更改，则在调用诸如count之类的事情或找到ActiveRecord对象之后，该表仍会与以前使用的表一起运行.

If the table name changes, after calling such a thing like count or a find the ActiveRecord object still operates with the table, which was used before.

如何才能重置 ActiveRecord 后代，以便在前缀，后缀，table_name更改时能与新设置一起使用?

How can reach to reset an ActiveRecord descendant, so that when the prefix, suffix, table_name changes it works with the new settings?

感谢您的帮助！

推荐答案

我找到了所描述行为的解释.尽管 reset_table_name 会重置根据前缀，后缀(可能还有其他东西)计算出的表名，但是在使用模型并生成查询时会初始化表. ActiveRecord 在关系代数宝石 Arel 的顶部"工作.使用 ActiveRecord 模型时，将创建一个表并填充 @arel_table 实例变量.此缓存是出于性能目的.如果要重新创建arel表，可以通过调用 reset_column_information 将其重置.我需要同时具有 reset_table_name 和 reset_column_information 才能获得新表名称的新表.如果我经常重置表，也许我将不得不担心性能.

I found the explanation for the described behavior. Although reset_table_name resets the table name computed from the prefix, suffix (and maybe other things too), the table is initialized when a model is used and a query is generated. ActiveRecord works "on the top of" Arel, a relational algebra gem. When an ActiveRecord model is used a table is created and filled @arel_table instance variable. This caching is for performance purposes. If one wants to recreate the arel table, it can be reset by calling reset_column_information. I needed to have both reset_table_name and reset_column_information in order to get a new table for the new table name. Probably I will have to worry about the performance, if I reset the table often.

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