Question

假设我在表格中有记录，每个记录都有一个图标属性，其中包含以下形式的网址：

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，而且更具可读性：

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"

Answer 2

直接正则表达怎么样：

validates_format_of :icon, :with =>  %r{^(balls\/)[A-Za-z]+\.(gif|jpg|png)$}i, :message => 'icon must start with balls'

Rails图像URL验证

2 个答案: