ActiveRecord选择除列之外

Question

有没有一种方法可以指定在ActiveRecord中选择所有列,只有少数几个.例如,对于用户,我不想选择他们的密码哈希或他们的电子邮件.这是可能的还是我必须手动硬编码所有列？

谢谢

Answer 1

写一个范围就好

def select_without columns
  select(column_names - columns.map(&:to_s))
end

Answer 2

像这样的东西？

exclude_columns = ['password', 'email']
columns = User.attribute_names.delete_if(|x| exclude_columns.include?(x))

User.select(columns)

编辑

我忘了我们可以做Array1 - Array2

最好的答案:

exclude_columns = ['password', 'email']
columns = User.attribute_names - exclude_columns

User.select(columns)

Answer 3

Another really usefull way it's with a scope inside the model in case you need to avoid a column constantly.

In my case I save images into blob fields so I want to avoid those to be loaded everytime and in a easy way:

scope :select_exclude_image, ->  { select( Movie.attribute_names - ['image'] ) }

Then to avoid the image in the selection you can do something like that:

Movie.select_exclude_image.first

or

Movie.select_exclude_image.all

I hope it will help!