Chapter 7, Task B1: Validating, Playtime

Why is ”:length” written with a colon before it and a => after, but “uniqueness” isn’t?

validates :title, uniqueness: true, :length => { :minimum => 10, :message => :too_short}

You are welcome to write that same line as follows:

validates :title, uniqueness: true, length: { minimum: 10, message: :too_short}

Note: message is typically a ‘string’ not a :symbol.

Ah, this makes so much more sense to my brain. Thank you.

How do I add a custom message for the “uniqueness: true” part?

app/views/products/_form.html.erb has full control over what is put in the HTML output.

Section 15.3 shows you how to override the value provided to you in full_message. You can provide an error.messages.taken string in the en translation.

For truly custom processing, you can write your own before_action callback (see chapter 20), and section 9.2 show you how to add custom messages.

I see. What I meant was, consider these two lines:

and

In the first one, since the numericality part takes a hash as its value, I can seem to add a custom message, like

However, in the second code uniqueness takes only “true” instead of a hash, so is there a way to put the custom message in code?

It doesn’t look like it—at the current time.

If this is something that interests you, consider looking into how to contribute to Rails. Lots of people do it. You can too!

Just wanted to add a few lines about the topic for people who run in to same problems as me which was with the regexp on the validation part. My validation with

 validates :image_url, allow_blank: true, format: {
    with:    %r{\.(gif|jpg|png)\$}i,
    message: 'must be a URL for GIF, JPG or PNG image.'
  }
 

 
validates :image_url, allow_blank: true, format: {
    with:    %r{\.(gif|jpg|png)\Z}i,                         # heres the change
    message: 'must be a URL for GIF, JPG or PNG image.'
  }