Rails图像URL验证

Question

假设我在一个表中有记录,并且每个都有一个图标属性,该属性采用表单的URL:

• 球/ x.png
• 球/ y.png
• 球/ z.png
• ...

如何编写验证,确保url以"balls /"开头,以.png,.gif结尾.还是.jpg？

我当前的验证只是检查文件扩展名:

validates_format_of :icon, :with => %r{\.(gif|jpg|png)$}i, :message => 'must be a URL for GIF, JPG ' + 'or PNG image.'

Answer 1

如何编写验证,确保url以"balls /"开头,以.png,.gif结尾.还是.jpg？

这将有效:

validates_format_of :icon,
  :with    => %r{^balls/.+\.(gif|jpe?g|png)$}i,
  :message => "must start with 'balls/' and have an image extension"

但是您可以在同一个字段上进行多次验证.所以,这也会起作用,并且更具可读性:

validates_format_of :icon,
  :with    => %r{^balls/.+}i,
  :message => "must start with 'balls/' and have a filename"

validates_format_of :icon,
  :with    => %r{\.(gif|jpe?g|png)$}i,
  :message => "must have an image extension"