哪里的created_at和updated_at字段从何而来？ [英] Where do the created_at and updated_at columns come from?

问题描述

所有的表由Rails应用程序创建的数据库似乎有created_at和updated_at字段。是什么造成这些？难道他们可选的，或者确实对他们一些内部的依赖？

All the tables in the database created by a rails application seem to have created_at and updated_at columns. What creates these? Are they optional, or does something internal rely on them?

推荐答案

他们在默认情况下，当你运行一个模型ActiveRecord的迁移创建。 ActiveRecord的自动填充/更新他们时，你分别创建或更新模型实例（因此底层数据库表行）。

They are created by default when you run the ActiveRecord migration for a model. ActiveRecord automatically populates/updates them when you create or update a model instance (and thus the underlying database table row) respectively.

您可以从模型迁移文件中删除 t.timestamps 行中删除列。

You can remove the columns by removing the t.timestamps line from within the model migration file.

• Ruby on Rails的指南：迁移

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