REGEX validation not working on Rails 4

Question

I'm using Rails 4.0 with Ruby 1.9.3. I have two REGEXs for validating two different fields:

PRICE_REGEX = /[0-9]+/
VALID_REGEX = /[a-zA-z0-9]*/

validates :price, presence: true, format: { with: PRICE_REGEX }
validates :title, length: { maximum: 20 }, format: { with: VALID_REGEX } #not a required field.

In my form, I'm using the form_for and have these fields represented as:

<li>
  <div class="msglabel">Price:</div>
  <%= f.text_field :price, class:"textArea" %>
</li>
<li>
  <div class="msglabel">Title:</div>
  <%= f.text_field :title, class:"textArea" %>
</li>

Unfortunately, neither of these are working. I can enter any ASCII character in either field and they will accept them. The VALID_REGEX works when I use

VALID_REGEX = /[a-zA-z0-9]+/

but then it won't accept an empty field, which I need it to because it isn't required.

What am I doing wrong and how can I rectify it?

EDIT

I've added the \A and \z anchors to the regex:

PRICE_REGEX = /\A[0-9]+\z/
VALID_REGEX = /\A[a-zA-Z0-9]*\z/

So VALID_REGEX is working but PRICE_REGEX won't even accept proper inputs now, such as 5000. I've tested it via Rubular, where it works perfectly, but my application just won't accept any input at all.

Anirudha · Accepted Answer · 2013-07-23 07:16:24Z

4

I guess you are missing \A(beginning of string),\z(end of string)

PRICE_REGEX = /\A[0-9]+\z/
VALID_REGEX = /\A[a-zA-Z0-9]*\z/

Without \A,\z it could match anywhere in middle like in the case of Hello! Hi which would match..With \A,\z you would explicitly match from start till end of string without matching anywhere in between

Refer to anchors in docs

edited Jul 23, 2013 at 7:16

answered Jul 23, 2013 at 6:20

Anirudha

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7 Comments

adnann Over a year ago

Tried it. Rails gave this error when I tried to load the page: "The provided regular expression is using multiline anchors (^ or $), which may present a security risk. Did you mean to use \A and \z, or forgot to add the :multiline => true option?"

adnann Over a year ago

Got it! Replaced ^ and $ with \A and \z as the error specified and it works now. Thanks!

adnann Over a year ago

One problem is persisting though that I didn't bother to check earlier on. The price field isn't accepting valid numbers now either with this regex.

Anirudha Over a year ago

@user2567161 by valid numbers do you mean decimal numbers

adnann Over a year ago

No, just normal numbers. For example: 5000

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