PostgreSQL 检查时间戳字段是否为空 [英] PostgreSQL check whether timestamp field is empty

问题描述

我遵循了这些说明 在登录时检查用户是否已被软删除.在下面的示例中，我可以检查布尔值:

I followed these instructions to check whether a user has been soft-deleted or not when logging in. In the example below I can check for a boolean value:

Class User < ActiveRecord::Base
  def self.find_for_authentication(conditions)
    super(conditions.merge(:deleted_flag => false))
  end

我更喜欢时间戳 (created_at) 字段.如何检查这样的字段是否为空?数据库为以下检查抛出错误:

I would prefer a timestamp (created_at) field. How can I check whether such a field is empty? The database throws errors for the following checks:

super(conditions.merge(:deleted_at => false)) # also tried nil, "NULL" and "IS NULL"

推荐答案

你不能使用这个解决方案，当然不修改设计.Devise 会将您的条件直接发送到数据库，因此无法调用方法或使用类似 squeel 的库(这将允许类似 where{created_at == nil}.

You can't using this solution, without modifying devise of course. Devise will send your conditions directly to the database, so no way of calling a method or using a library like squeel (that will allow something like where{created_at == nil}.

您可以使用How to "软删除"使用 Devise 的用户，但错误消息将是:您必须先确认您的帐户，然后才能继续."

You could use the solution provided in How to "soft delete" user with Devise, but the error message will be: "You have to confirm your account before continuing."

将此添加到您的资源模型:

Add this to your resource model:

  def inactive_message
    !!deleted_at ? :deleted : super
  end

并向您的语言环境添加一条消息:

And add a message to your locales:

en:
  devise:
    failure:
      deleted: "Your account was deleted."

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