根据属性值Rails的对象过滤数组 [英] Rails filtering array of objects by attribute value

问题描述

所以，我执行查询的数据库，我有对象的完整的数组：

So I perform a query to the db and I have a complete array of objects:

@attachments = Job.find(1).attachments

现在，我有对象，我不希望执行另一个数据库查询的数组，但我想过滤的基础上附件对象的<$数组C $ C> FILE_TYPE ，这样我可以有附件列表其中，文件类型为标志键，然后附件另一个列表其中，文件类型为图像

Now that I have an array of objects I don't want to perform another db query, but I would like to filter the array based on the Attachment object's file_type so that I can have a list of attachments where the file type is 'logo' and then another list of attachments where the file type is 'image'

事情是这样的：

@logos  = @attachments.where("file_type = ?", 'logo')
@images = @attachments.where("file_type = ?", 'image')

但在内存中，而不是一个数据库查询。

But in memory instead of a db query.

干杯

推荐答案

尝试：

这是罚款：

@logos = @attachments.select { |attachment| attachment.file_type == 'logo' }
@images = @attachments.select { |attachment| attachment.file_type == 'image' }

但性能明智的，你不需要重复两次@attachments：

but for performance wise you don't need to iterate @attachments twice :

@logos , @images = [], []
@attachments.each do |attachment|
  @logos << attachment if attachment.file_type == 'logo'
  @images << attachment if attachment.file_type == 'image'
end

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