Suppose I only want user to type in url starts with http://www.google.com
What is the regular expression for this?
Thanks!
Just get the substring from 0 to the length of http://www.google.com and you're done.
Rather than use a regex, you might want to consider using the URI library that comes with Ruby. It's made to take apart and build URLs, is well tested, and less error-prone than trying to reinvent the same functionality.
require 'uri'
url = URI.parse('http://www.google.com/path/to/page.html?a=1&b=2')
url.scheme # => "http"
url.host # => "www.google.com"
url.path # => "/path/to/page.html"
url.query # => "a=1&b=2"
If that's not good enough, the Addressable::URI gem is even more capable.
Try this:
/\Ahttp:\/\/www\.google\.com(.*)?\Z/
ruby-1.9.2-p0 > "http://www.google.com" =~ /\Ahttp:\/\/www\.google\.com(.*)?\Z/
=> 0
ruby-1.9.2-p0 > "http://www.google.com/foobar" =~ /\Ahttp:\/\/www\.google\.com(.*)?\Z/
=> 0
ruby-1.9.2-p0 > $1
=> "/foobar"
Rails has a convenient start_with? method for this. If it's just a static string, no regular expression is needed.
url.start_with?("http://www.google.com")
Related
In console of rails 4.2.7, I have the following test:
[45] pry(main)> '#$'
=> "\#$"
[46] pry(main)> '##'
=> "\##"
[47] pry(main)> '#!'
=> "#!"
[48] pry(main)> '#ab'
=> "#ab"
It seems rails will only put a "\" before the string when there is an # or $ after #.
The problem leads me to this test is that I have a erb file that render a data attribute with an array of json:
data-xx="<%= [{xx: '#$', yy: 'yy'}.to_json, {zz: 'zzz'}.to_json] %>"
Then in chrome console, it will give the unexpected result as
$("#entry_show_modal_template").data('xx')
"["{\"xx\":\"\#$\",\"yy\":\"yy\"}", "{\"zz\":\"zzz\"}"]"
And when I change xx value from #! or some other string, the result will be ok as an array
$("#entry_show_modal_template").data('xx')
["{"xx":"#!","yy":"yy"}", "{"zz":"zzz"}"]
Does someone know if it is true and why it has such difference?
And it there any way to tackle this problem?
This is not true.
In '#{...}' hash will also be escaped. This is done to prevent recursive/implicit string interpolation.
Look:
$a = 'hello'
"#$a"
#⇒ "hello"
The problem is already solved by ruby for you. Just use the produced string as is and don’t be fooled by the way it is printed out in console.
"\#$".length
#⇒ 2
"\#$" == '#$'
#⇒ true
"\#$"[0]
#⇒ "#"
#mudasobwa's explaination is correct
According to your situation you should try in this way
===> In rails console
json_values = [{xx: '#$', yy: 'yy'}, {zz: 'zzz'}].to_json
===> In chrome console
result = JSON.parse(json_values)
you will get expected array, its just ruby technique to handle string interpolation thing
Given URLs like:
http://online.wsj.com/
http://online.wsj.com/article/SB10001424052970204409004577158764211274708.html
http://www.techcrunch.com/2012/01/13/techcrunch-coo/
Using Ruby/Rails, how can I return back just the domain?
online.wsj.com
online.wsj.com
techcrunch.com
No protocol, no slashes, just the subdomain if it's not www, and the domain, and ext?
Use Addressable::URI.parse and the #host instance method:
Addressable::URI.parse("http://techcrunch.com/foo/bar").host #=> "techcrunch.com"
Be aware that if you have an url without http://, this returns nil:
require 'uri'
url = "www.techcrunch.com/2012/01/13/techcrunch-coo/"
p URI.parse(url).host # nil
So something like this should be a safer solution:
require 'uri'
url = "www.techcrunch.com/2012/01/13/techcrunch-coo/"
url = 'http://' + url unless url.match(/^http:\/\//)
puts URI.parse(url).host
pry(main)> require 'uri'
pry(main)> url = "http://www.techcrunch.com/2012/01/13/techcrunch-coo?param1=foo¶m2=bar"
pry(main)> URI.parse(url).host
=> "www.techcrunch.com"
>> require 'uri'
>> URI.parse("http://www.techcrunch.com/2012/01/13/techcrunch-coo/").host
=> "www.techcrunch.com"
I have an Image, which contains carrierwave uploads:
Image.find(:first).image.url #=> "/uploads/image/4d90/display_foo.jpg"
In my view, I want to find the absolute url for this. Appending the root_url results in a double /.
root_url + image.url #=> http://localhost:3000//uploads/image/4d90/display_foo.jpg
I cannot use url_for (that I know of), because that either allows passing a path, or a list of options to identify the resource and the :only_path option. Since I do't have a resource that can be identified trough "controller"+"action" I cannot use the :only_path option.
url_for(image.url, :only_path => true) #=> wrong amount of parameters, 2 for 1
What would be the cleanest and best way to create a path into a full url in Rails3?
You can also set CarrierWave's asset_host config setting like this:
# config/initializers/carrierwave.rb
CarrierWave.configure do |config|
config.storage = :file
config.asset_host = ActionController::Base.asset_host
end
This ^ tells CarrierWave to use your app's config.action_controller.asset_host setting, which can be defined in one of your config/envrionments/[environment].rb files. See here for more info.
Or set it explicitly:
config.asset_host = 'http://example.com'
Restart your app, and you're good to go - no helper methods required.
* I'm using Rails 3.2 and CarrierWave 0.7.1
try path method
Image.find(:first).image.path
UPD
request.host + Image.find(:first).image.url
and you can wrap it as a helper to DRY it forever
request.protocol + request.host_with_port + Image.find(:first).image.url
Another simple method to use is URI.parse, in your case would be
require 'uri'
(URI.parse(root_url) + image.url).to_s
and some examples:
1.9.2p320 :001 > require 'uri'
=> true
1.9.2p320 :002 > a = "http://asdf.com/hello"
=> "http://asdf.com/hello"
1.9.2p320 :003 > b = "/world/hello"
=> "/world/hello"
1.9.2p320 :004 > c = "world"
=> "world"
1.9.2p320 :005 > d = "http://asdf.com/ccc/bbb"
=> "http://asdf.com/ccc/bbb"
1.9.2p320 :006 > e = "http://newurl.com"
=> "http://newurl.com"
1.9.2p320 :007 > (URI.parse(a)+b).to_s
=> "http://asdf.com/world/hello"
1.9.2p320 :008 > (URI.parse(a)+c).to_s
=> "http://asdf.com/world"
1.9.2p320 :009 > (URI.parse(a)+d).to_s
=> "http://asdf.com/ccc/bbb"
1.9.2p320 :010 > (URI.parse(a)+e).to_s
=> "http://newurl.com"
Just taking floor's answer and providing the helper:
# Use with the same arguments as image_tag. Returns the same, except including
# a full path in the src URL. Useful for templates that will be rendered into
# emails etc.
def absolute_image_tag(*args)
raw(image_tag(*args).sub /src="(.*?)"/, "src=\"#{request.protocol}#{request.host_with_port}" + '\1"')
end
There's quite a bunch of answers here. However, I didn't like any of them since all of them rely on me to remember to explicitly add the port, protocol etc. I find this to be the most elegant way of doing this:
full_url = URI( root_url )
full_url.path = Image.first.image.url
# Or maybe you want a link to some asset, like I did:
# full_url.path = image_path("whatevar.jpg")
full_url.to_s
And what is the best thing about it is that we can easily change just one thing and no matter what thing that might be you always do it the same way. Say if you wanted to drop the protocol and and use the The Protocol-relative URL, do this before the final conversion to string.
full_url.scheme = nil
Yay, now I have a way of converting my asset image urls to protocol relative urls that I can use on a code snippet that others might want to add on their site and they'll work regardless of the protocol they use on their site (providing that your site supports either protocol).
I used default_url_options, because request is not available in mailer and avoided duplicating hostname in config.action_controller.asset_host if haven't specified it before.
config.asset_host = ActionDispatch::Http::URL.url_for(ActionMailer::Base.default_url_options)
You can't refer to request object in an email, so how about:
def image_url(*args)
raw(image_tag(*args).sub /src="(.*?)"/, "src=\"//#{ActionMailer::Base.default_url_options[:protocol]}#{ActionMailer::Base.default_url_options[:host]}" + '\1"')
end
You can actually easily get this done by
root_url[0..-2] + image.url
I agree it doesn't look too good, but gets the job done.. :)
I found this trick to avoid double slash:
URI.join(root_url, image.url)
when I do this
ip = request.env["REMOTE_ADDR"]
I get the client's IP address it it. But what if I want to validate whether the value in the variable is really an IP?
How do I do that?
Please help.
Thanks in advance. And sorry if this question is repeated, I didn't take the effort of finding it...
EDIT
What about IPv6 IP's??
Ruby has already the needed Regex in the standard library.
Checkout resolv.
require "resolv"
"192.168.1.1" =~ Resolv::IPv4::Regex ? true : false #=> true
"192.168.1.500" =~ Resolv::IPv4::Regex ? true : false #=> false
"ff02::1" =~ Resolv::IPv6::Regex ? true : false #=> true
"ff02::1::1" =~ Resolv::IPv6::Regex ? true : false #=> false
If you like it the short way ...
require "resolv"
!!("192.168.1.1" =~ Resolv::IPv4::Regex) #=> true
!!("192.168.1.500" =~ Resolv::IPv4::Regex) #=> false
!!("ff02::1" =~ Resolv::IPv6::Regex) #=> true
!!("ff02::1::1" =~ Resolv::IPv6::Regex) #=> false
Have fun!
Update (2018-10-08):
From the comments below i love the very short version:
!!(ip_string =~ Regexp.union([Resolv::IPv4::Regex, Resolv::IPv6::Regex]))
Very elegant with rails (also an answer from below):
validates :ip,
:format => {
:with => Regexp.union(Resolv::IPv4::Regex, Resolv::IPv6::Regex)
}
Why not let a library validate it for you? You shouldn't introduce complex regular expressions that are impossible to maintain.
% gem install ipaddress
Then, in your application
require "ipaddress"
IPAddress.valid? "192.128.0.12"
#=> true
IPAddress.valid? "192.128.0.260"
#=> false
# Validate IPv6 addresses without additional work.
IPAddress.valid? "ff02::1"
#=> true
IPAddress.valid? "ff02::ff::1"
#=> false
IPAddress.valid_ipv4? "192.128.0.12"
#=> true
IPAddress.valid_ipv6? "192.128.0.12"
#=> false
You can also use Ruby's built-in IPAddr class, but it doesn't lend itself very well for validation.
Of course, if the IP address is supplied to you by the application server or framework, there is no reason to validate at all. Simply use the information that is given to you, and handle any exceptions gracefully.
require 'ipaddr'
!(IPAddr.new(str) rescue nil).nil?
I use it for quick check because it uses built in library. Supports both ipv4 and ipv6. It is not very strict though, it says '999.999.999.999' is valid, for example. See the winning answer if you need more precision.
As most of the answers don't speak about IPV6 validation, I had the similar problem.
I solved it by using the Ruby Regex Library, as #wingfire mentionned it.
But I also used the Regexp Library to use it's union method as explained here
I so have this code for a validation :
validates :ip, :format => {
:with => Regexp.union(Resolv::IPv4::Regex, Resolv::IPv6::Regex)
}
Hope this can help someone !
Use http://www.ruby-doc.org/stdlib-1.9.3/libdoc/ipaddr/rdoc/IPAddr.html it performs validation for you. Just rescue the exception with false and you know that it was invalid.
1.9.3p194 :002 > IPAddr.new('1.2.3.4')
=> #<IPAddr: IPv4:1.2.3.4/255.255.255.255>
1.9.3p194 :003 > IPAddr.new('1.2.3.a')
ArgumentError: invalid address
from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/ipaddr.rb:496:in `rescue in initialize'
from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/ipaddr.rb:493:in `initialize'
from (irb):3:in `new'
from (irb):3
from /usr/local/rvm/rubies/ruby-1.9.3-p194/bin/irb:16:in `<main>'
require 'ipaddr'
def is_ip?(ip)
!!IPAddr.new(ip) rescue false
end
is_ip?("192.168.0.1")
=> true
is_ip?("www.google.com")
=> false
Or, if you don't mind extending core classes:
require 'ipaddr'
class String
def is_ip?
!!IPAddr.new(self) rescue false
end
end
"192.168.0.1".is_ip?
=> true
"192.168.0.512".is_ip?
=> false
All answers above asume IPv4... you must ask yourself how wise it is to limit you app to IPv4 by adding these kind of checks in this day of the net migrating to IPv6.
If you ask me: Don't validate it at all. Instead just pass the string as-is to the network components that will be using the IP address and let them do the validation. Catch the exceptions they will throw when it is wrong and use that information to tell the user what happened. Don't re-invent the wheel, build upon the work of others.
Try this
Use IPAddr
require 'ipaddr'
true if IPAddr.new(ip) rescue false
This regular expression I use which I found here
/^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/
IP address in a string form must contain exactly four numbers, separated by dots. Each number must be in a range between 0 and 255, inclusive.
Validate using regular expression:
\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}
for match a valid IP adress with regexp use
^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$
instead of
^([01]?[0-9][0-9]?|2[0-4][0-9]|25[0-5])(\.([01]?[0-9][0-9]?|2[0-4][0-9]|25[0-5])){3}$
because many regex engine match the first possibility in the OR sequence
you can try your regex engine : 10.48.0.200
test the difference here
for ipv4
def ipv4?(str)
nums = str.split('.')
reg = /^\d$|^[1-9]\d$|^1\d\d$|^2[0-4]\d$|^25[0-5]$/
nums.length == 4 && (nums.count {|n| reg.match?(n)}) == 4
end
Basically url escapes a string except uses '+' instead of '%20' for spaces.
CGI::escape does just that:
irb(main):003:0> require 'cgi'
=> true
irb(main):004:0> CGI::escape("foo and/or bar")
=> "foo+and%2For+bar"