这是我的
Image模型,我在其中实现了一种验证附件尺寸的方法：
class Image < ActiveRecord::Base
attr_accessible :file
belongs_to :imageable,polymorphic: true
has_attached_file :file,styles: { thumb: '220x175#',thumb_big: '460x311#' }
validates_attachment :file,presence: true,size: { in: 0..600.kilobytes },content_type: { content_type: 'image/jpeg' }
validate :file_dimensions
private
def file_dimensions(width = 680,height = 540)
dimensions = Paperclip::Geometry.from_file(file.queued_for_write[:original].path)
unless dimensions.width == width && dimensions.height == height
errors.add :file,"Width must be #{width}px and height must be #{height}px"
end
end
end
这工作正常,但它不可重复使用,因为该方法采用宽度和宽度的固定值.高度.我想将其转换为自定义验证器,因此我也可以在其他模型中使用它.我已经阅读了有关此内容的指南,我知道在app / models / dimensions_validator.rb中它会是这样的：
class DimensionsValidator < ActiveModel::EachValidator
def validate_each(record,attribute,value)
dimensions = Paperclip::Geometry.from_file(record.queued_for_write[:original].path)
unless dimensions.width == 680 && dimensions.height == 540
record.errors[attribute] << "Width must be #{width}px and height must be #{height}px"
end
end
end
但我知道我遗漏了一些因为这段代码不起作用.问题是我想在我的模型中调用这样的验证：
验证：附件,尺寸：{宽度：300,高度：200}.
有关如何实施此验证器的任何想法？
解决方法
把它放在app / validators / dimensions_validator.rb中：
class DimensionsValidator < ActiveModel::EachValidator
def validate_each(record,value)
# I'm not sure about this:
dimensions = Paperclip::Geometry.from_file(value.queued_for_write[:original].path)
# But this is what you need to know:
width = options[:width]
height = options[:height]
record.errors[attribute] << "Width must be #{width}px" unless dimensions.width == width
record.errors[attribute] << "Height must be #{height}px" unless dimensions.height == height
end
end
然后,在模型中：
validates :file,:dimensions => { :width => 300,:height => 300 }