method

validates_format_of

Ruby on Rails latest stable (v2.2.1) - 2 notes - Class: ActiveModel::Validations::ClassMethods

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What's this?

validates_format_of(*attr_names) public

Validates whether the value of the specified attribute is of the correct form by matching it against the regular expression provided.

  class Person < ActiveRecord::Base
    validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i, :on => :create
  end

Note: use \A and \Z to match the start and end of the string, ^ and $ match the start/end of a line.

A regular expression must be provided or else an exception will be raised.

Configuration options:

:message - A custom error message (default is: "is invalid")
:allow_nil - If set to true, skips this validation if the attribute is nil (default is: false)
:allow_blank - If set to true, skips this validation if the attribute is blank (default is: false)
:with - The regular expression used to validate the format with (note: must be supplied!)
:on - Specifies when this validation is active (default is :save, other options :create, :update)
:if - Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value.
:unless - Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.

Show source

# File activemodel/lib/active_model/validations/format.rb, line 27
      def validates_format_of(*attr_names)
        configuration = { :message => ActiveRecord::Errors.default_error_messages[:invalid], :on => :save, :with => nil }
        configuration.update(attr_names.extract_options!)

        raise(ArgumentError, "A regular expression must be supplied as the :with option of the configuration hash") unless configuration[:with].is_a?(Regexp)

        validates_each(attr_names, configuration) do |record, attr_name, value|
          record.errors.add(attr_name, configuration[:message]) unless value.to_s =~ configuration[:with]
        end
      end

August 8, 2008

10 thanks

Using validates_format_of to validate URIs

You can use the validates_format_of with the regular expression in the URI library ensure valid URIs.

Example

  require 'uri'

  class Feed < ActiveRecord::Base
    validates_format_of :uri, :with => URI.regexp
  end

August 11, 2008

5 thanks

RE: Using validates_format_of to validate URIs

Further to Olly’s note below, you can also specify the protocol to further limit the valid uri’s, else things like ‘ftp ://someurl.com’ (there’s only a space in there to get it to display on here) would be valid.

  validates_format_of :uri, :with => URI.regexp(['http'])

validates_format_of

Related methods

Using validates_format_of to validate URIs

Example

RE: Using validates_format_of to validate URIs