如何获得当前载波实例的宽度和高度？
像这样的东西：
car_images.each do | image| image_tag( image.photo_url,:width => image.photo_width,:height => image.photo_height) end
不幸的是,image.photo_width和image.photo_height无效.
我需要指定图像的宽度和高度,这是我正在使用的jquery插件所必需的.
解决方法
结合
https://github.com/jnicklas/carrierwave/wiki/How-to:-Get-version-image-dimensions和
https://github.com/jnicklas/carrierwave/wiki/How-to:-Store-the-uploaded-file-size-and-content-type,你会得到：
class Image
before_save :update_image_attributes
private
def update_image_attributes
if image.present?
self.content_type = image.file.content_type
self.file_size = image.file.size
self.width,self.height = `identify -format "%wx%h" #{image.file.path}`.split(/x/)
# if you also need to store the original filename:
# self.original_filename = image.file.filename
end
end
end