I'm reading agile web development with rails 6.
In chapter 7, Task B: validation and unite testing
class Product < ApplicationRecord
validates :image_url, allow_blank: true, format: {
with: %r{\.(gif|jpg|png)\z}i,
}
what does the i mean in the end here?
It should mean that it's ending with .git or .jpg or .png
The i in your query tells the regex to match using a case insensitive match. There is nothing really unique to rails here so you may want to look into regexes in general to learn all the different terms you can use to modify your expression.
The expression %r{\.(gif|jpg|png)\z}i is equivalent to /\.(gif|jpg|png)\z/i
the \. means the period character
the | is an or as you stated
the \z is end of string with some caveats that you can read more about here: http://www.regular-expressions.info/anchors.html
and the i is incentive case matching
This means you would match 'test.jpg', 'test.JPg', 'test.JPG' or any permutation of those three characters in any case preceded by a period that occurs at the end of the string.
Here are the docs for regex formats in ruby specific:
https://ruby-doc.org/2.7.7/Regexp.html
And here is something where you can play with and learn regexes in general and try some expressions yourself:
short explain: The "i" at the end of the regular expression is a modifier that makes the expression case-insensitive. This means that it will match both upper and lowercase letters in the image URL.
