I am using a user input string to create a url and I only want the url to contain lowercase letters and hyphens
e.g. example.com/this-is-a-url
In my model, I have added so far:
def to_param
name.downcase.gsub(" ", "-")
end
This makes it lowercase and hyphenated. How can I remove all illegal characters, such as '/"$£%& and so on? A regular expression might be the answer but is there something built in for this purpose already in Rails?
Perhaps instead of doing the above, I should create a validation that makes sure that 'name' is only spaces and letters? Is there something built in for this purpose?
You can use ActiveSupport's parameterize method:
def to_param
name.parameterize
end
parameterize API documentation
You might consider the to_slug plugin for this. See also this related question.
Related
For example, to get the full name of a User model with first_name and last_name attributes, one could write:
def full_name
self.name_first + " " + self.name_last
end
or
def full_name
"#{self.name_first} #{self.name_last}"
end
I've noticed that I personally prefer the latter. It may be subjective, but which is generally preferred? What are the advantages/ disadvantages?
According to the community Ruby coding style guide (https://github.com/bbatsov/ruby-style-guide#string-interpolation):
Prefer string interpolation and string formatting instead of string concatenation
Also, regarding self (https://github.com/bbatsov/ruby-style-guide#no-self-unless-required):
Avoid self where not required. (It is only required when calling a self write accessor.)
So, finally this method could be something like:
def full_name
"#{name_first} #{name_last}"
end
The first version – concatenating with + – will raise an error if either attribute is nil or is not of type String.
The second version – using expression substitution – calls to_s on everything substituted, so nil becomes "" and therefore wouldn't raise an error. This also applies to other classes such as Array, Hash, etc. that implement to_s.
I'm trying to strip the whitespaces of the variable Username in my User Model.
I'm using
before_save do
self.username.strip!
end
but it doesn't seem to work, am i missing something ?
You'd rather update the setter instead of polluting your model with callbacks:
def username=(value)
self[:username] = value.to_s.strip
end
Btw, I prefer squish
If you want to remove only leading and trailing white space you can use .strip!
But as you said:
I'm trying to strip the whitespaces of the variable Username in my
User Model.
I think actually you want to remove all spaces following should do:
.gsub(/\s+/, "")
EDIT:
Oh yes, You can also use Rail's built-in method squish()
thanx to apneadiving for reminding
I'm developing a web application using rails.
For aesthetic purposes, i need to replace %20 with -
Before: http://localhost:3000/movies/2006/Apna%20Sapna%20Money%20Money
After: http://localhost:3000/movies/2006/Apna-Sapna-Money-Money
Is there anyway i can achieve this in rails?
You should use URI.parse to break it into pieces and then change only the path component:
require 'uri'
u = URI.parse(url)
u.path = u.path.gsub('%20', '-')
url = u.to_s
Just a simple gsub on the whole URL would probably work fine but a little extra paranoia might save you some confusion and suffering down the road. Also, if you're just replacing a literal string rather than a regular expression, you can use a String as the first argument to gsub and avoid some escaping issues:
The pattern is typically a Regexp; if given as a String, any regular expression metacharacters it contains will be interpreted literally, e.g. '\\d' will match a backlash followed by d, instead of a digit.
If your string is stored in the variable url you can use
url.gsub(/%20/, "-")
to return the string you want, or
url.gsub!(/%20/, "-")
to actually modify the value of url with the value you want.
https://github.com/FriendlyId/friendly_id
this is the best way to go about seo urls
You probably want to be saving "Apna-Sapna-Money-Money" within your Movies model as an attribute (I usually call these slugs). Then, to generate these, you might just need to replace spaces in the movie title with hyphens. Something like:
class Movie
before_create :generate_slug
private
def generate_slug
slug = title.gsub(" ", "-")
end
end
Then in your controller action you can simply do a Movie.find_by_slug!(params[:id]) call.
Basically, there should be no reason for users to ever arrive at a URL with %20 in it...
i have
string = "$575.00 "
string.to_f
// => 0.0
string = "575.00 "
string.to_f
// => 575.0
the value coming in is in this format and i need to insert into a database field that is decimal any suggestions
"$575.00 "
We did this so often we wrote an extension to String called cost_to_f:
class String
def cost_to_f
self.delete('$,').to_f
end
end
We store such extensions in config/initializers/extensions/string.rb.
You can then simply call:
"$5,425.55".cost_to_f #=> 5425.55
If you are using this method rarely, the best bet is to simply create a function, since adding functions to core classes is not exactly something I would recommend lightly:
def cost_to_f(string)
string.delete('$,').to_f
end
If you need it in more than one class, you can always put it in a module, then include that module wherever you need it.
One more tidbit. You mentioned that you need to process this string when it is being written to the database. With ActiveRecord, the best way to do this is:
class Item < ActiveRecord::Base
def price=(p)
p = p.cost_to_f if p.is_a?(String)
write_attribute(:price, p)
end
end
EDIT: Updated to use String#delete!
So many answers... i'll try to summarize all that are available now, before give own answer.
1. string.gsub(/[\$,]/, '')
string.gsub!(/^\$/, '')
2. string[1..-1]
3. string.slice(0) # => "ome string"
4. s/^.//
Why (g)sub and regexp Just for deleting a character? String#tr is faster and shorter. String#delete is even better.
Good, fast, simple. Power of reverse indexing.
Hm... looks like it returns "S". Because it is an alias to String#[]
Perl? /me is cheking question tags...
And my advice is:
What if you have not dollar, but yena? Or what if you don't even have anything before numbers?
So i'll prefer:
string[/\d.+/]
This will crop leading non-decimal symbols, that prevent to_f to work well.
P.S.: By the way. It's known, that float is bad practice for storing money amounts.
Use Float or Decimal for Accounting Application Dollar Amount?
You could try something like this.
string = string[1..-1] if string.match(/^\$/)
Or this.
string.gsub!(/^\$/, '')
Remember to put that backslash in your Regexp, it also means "end of string."
you can use regex for that:
s/^.//
As laways, this is PCRE syntax.
In Ruby, you can use the sub() method of the string class to replace the string:
result = string.sub(/^./,"")
This should work.
[EDIT]
Ok, someone asked what's the gsub() is for:
gsub() acts like sub() but with the /g modifier in PCRE (for global replacement):
s/a/b/
in PCRE is
string.sub(/a/, "b")
and
s/a/b/g
is
string.gsub(/a/, "b")
in Ruby
What I'd use (instead of regular expressions) is simply the built-in slice! method in the String class. For example,
s = "Some string"
s.slice!(0) # Deletes and returns the 0th character from the string.
s # => "ome string"
Documentation here.
I am currently developing a CMS and want to encode special chars in the URL in a nice way.
I don't want to use Rack::Utils.escape.
Is there already a cool gem available?
Best regards
Look at the stringex gem here, it can be used even without rails, but contains some stuff to make it easier to use(with rails).
Ruby's CGI library should do what you need:
url_encoded_string = CGI::escape("'Stop!' said Fred")
# => "%27Stop%21%27+said+Fred"
See http://ruby-doc.org/core/classes/CGI.html
Well, I normally use a handy custom-made method called String.to_slug. I hope you find it useful.
Call this /lib/to_slug.rb and include it in one initializer, or include it only on the model that generates the urls.
String.class_eval do
#converts accented letters into ascii equivalents (eg. ñ becomes n)
def normalize
#this version is in the forums but didn't work for me
#chars.normalize(:kd).gsub!(/[^\x00-\x7F]/n,'').to_s
mb_chars.normalize(:d).gsub(/[^\x00-\x7F]/n,'').to_s
end
#returns an array of strings containing the words on a string
def words
gsub(/\W/, ' ').split
end
#convert into a nice url-ish string
def to_slug(separator='-')
strip.downcase.normalize.words.join(separator)
end
end