Tidy long string in Ruby - ruby-on-rails

I have a method in Ruby, which needs an API URL:
request_url = "http://api.abc.com/v3/avail?rev=#{ENV['REV']}&key=#{ENV['KEY']}&locale=en_US&currencyCode=#{currency}&arrivalDate=#{check_in}&departureDate=#{check_out}&includeDetails=true&includeRoomImages=true&room1=#{total_guests}"
I want to format it to be more readable. It should take arguments.
request_url = "http://api.abc.com/v3/avail?
&rev=#{ENV['REV']}
&key=#{ENV['KEY']}
&locale=en_US
&currencyCode=#{currency}
&arrivalDate=#{check_in}
&departureDate=#{check_out}
&includeDetails=true
&includeRoomImages=true
&room1=#{total_guests}"
But of course there's line break. I tried heredoc, but I want it to be in one line.

I would prefer to not build URI queries by joining strings, because that might lead to URLs that are not correctly encoded (see a list of characters that need to be encoded in URIs).
There is the Hash#to_query method in Ruby on Rails that does exactly what you need and it ensure that the parameters are correctly URI encoded:
base_url = 'http://api.abc.com/v3/avail'
arguments = {
rev: ENV['REV'],
key: ENV['KEY'],
locale: 'en_US',
currencyCode: currency,
arrivalDate: check_in,
departureDate: check_out,
includeDetails: true,
includeRoomImages: true,
room1: total_guests
}
request_url = "#{base_url}?#{arguments.to_query}"

You could use an array and join the strings:
request_url = [
"http://api.abc.com/v3/avail?",
"&rev=#{ENV['REV']}",
"&key=#{ENV['KEY']}",
"&locale=en_US",
"&currencyCode=#{currency}",
"&arrivalDate=#{check_in}",
"&departureDate=#{check_out}",
"&includeDetails=true",
"&includeRoomImages=true",
"&room1=#{total_guests}",
].join('')
Even easier, you can use the %W array shorthand notation so you don't have to write out all the quotes and commas:
request_url = %W(
http://api.abc.com/v3/avail?
&rev=#{ENV['REV']}
&key=#{ENV['KEY']}
&locale=en_US
&currencyCode=#{currency}
&arrivalDate=#{check_in}
&departureDate=#{check_out}
&includeDetails=true
&includeRoomImages=true
&room1=#{total_guests}
).join('')
Edit: Of course, spickermann makes a very good point above on better ways to accomplish this specifically for URLs. However, if you're not constructing a URL and just working with strings, the above methods should work fine.

You can extend strings in Ruby using the line continuation operator. Example:
request_url = "http://api.abc.com/v3/avail?" \
"&rev=#{ENV['REV']}" \
"&key=#{ENV['KEY']}"

Related

How to have gsub handle multiple patterns and replacements

A while ago I created a function in PHP to "twitterize" the text of tweets pulled via Twitter's API.
Here's what it looked like:
function twitterize($tweet){
$patterns = array ( "/((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+#)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+#)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%#.\w_]*)#?(?:[\w]*))?)/",
"/(?<=^|(?<=[^a-zA-Z0-9-\.]))#([A-Za-z_]+[A-Za-z0-9_]+)/",
"/(?<=^|(?<=[^a-zA-Z0-9-\.]))#([A-Za-z_]+[A-Za-z0-9_]+)/");
$replacements = array ("<a href='\\0' target='_blank'>\\0</a>", "<a href='http://twitter.com/\\1' target='_blank'>\\0</a>", "<a href='http://twitter.com/search?q=\\1&src=hash' target='_blank'>\\0</a>");
return preg_replace($patterns, $replacements, $tweet);
}
Now I'm a little stuck with Ruby's gsub, I tried:
def twitterize(text)
patterns = ["/((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+#)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+#)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%#.\w_]*)#?(?:[\w]*))?)/", "/(?<=^|(?<=[^a-zA-Z0-9-\.]))#([A-Za-z_]+[A-Za-z0-9_]+)/", "/(?<=^|(?<=[^a-zA-Z0-9-\.]))#([A-Za-z_]+[A-Za-z0-9_]+)/"]
replacements = ["<a href='\\0' target='_blank'>\\0</a>",
"<a href='http://twitter.com/\\1' target='_blank'>\\0</a>",
"<a href='http://twitter.com/search?q=\\1&src=hash' target='_blank'>\\0</a>"]
return text.gsub(patterns, replacements)
end
Which obviously didn't work and returned an error:
No implicit conversion of Array into String
And after looking at the Ruby documentation for gsub and exploring a few of the examples they were providing, I still couldn't find a solution to my problem: How can I have gsub handle multiple patterns and multiple replacements at once?
Well, as you can read from the docs, gsub does not handle multiple patterns and replacements at once. That's what causing your error, quite explicit otherwise (you can read that as "give me a String, not an Array!!1").
You can write that like this:
def twitterize(text)
patterns = [/((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+#)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+#)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%#.\w_]*)#?(?:[\w]*))?)/, /(?<=^|(?<=[^a-zA-Z0-9-\.]))#([A-Za-z_]+[A-Za-z0-9_]+)/, /(?<=^|(?<=[^a-zA-Z0-9-\.]))#([A-Za-z_]+[A-Za-z0-9_]+)/]
replacements = ["<a href='\\0' target='_blank'>\\0</a>",
"<a href='http://twitter.com/\\1' target='_blank'>\\0</a>",
"<a href='http://twitter.com/search?q=\\1&src=hash' target='_blank'>\\0</a>"]
patterns.each_with_index do |pattern, i|
text.gsub!(pattern, replacements[i])
end
text
end
This can be refactored into more elegant rubyish code, but I think it'll do the job.
The error was because you tried to use an array of replacements in the place of a string in the gsub function. Its syntax is:
text.gsub(matching_pattern,replacement_text)
You need to do something like this:
replaced_text = text.gsub(pattern1, replacement1)
replaced_text = replaced_text.gsub(pattern2, replacement2)
and so on, where the pattern 1 is one of your matching patterns and replacement is the replacement text you would like.

ruby regex with quotes

I'm trying to pass more than one regex parameter for parts of a string that needs to be replaced. Here's the string:
str = "stands in hall "Let's go get to first period everyone" Students continue moving to seats."
Here is the expected string:
str = "stands in hall "Let's go get to first period everyone" Students continue moving to seats."
This is what I tried:
str.gsub(/'|"/, "'" => "\'", """ => "\"")
This is what I got:
"stands in hall \"Let's go get to first period everyone\" Students continue moving to seats."
How do I get the quotes in while sending in two regex parameters using gsub?
This is an HTML unescaping problem.
require 'cgi'
CGI.unescape_html(str)
This gives you the correct answer.
From my comments on this question:
Your updated version is correct. The only reason the slashes are in your final line of code is that it's an escape sequence so that you don't mistakenly think the first slash is used to terminate the string. Try assigning your output and printing it:
str1 = str.gsub(/'|"/, "'" => "\'", """ => "\"")
puts str1
and you'll see that the slashes are gone when str1 is printed using puts.
The difference is that autoevaluating variables within irb (which is what I assume you're doing to execute this sample code) automatically calls the inspect method, which for string variables shows the string in its entirety.
Because I did not understand unescaping characters I found an alternative solution that might be the "rails-way"
Can you use <%= raw 'some_html' %>
My final solution ended up being this instead of messy regex and requiring CGI
<%= raw evidence_score.description %>
Unescaping HTML string in Rails

URI encoding not working

On a rails app, I need to parse uris
a = 'some file name.txt'
URI(URI.encode(a)) # works
b = 'some filename with :colon in it.txt'
URI(URI.encode(b)) # fails URI::InvalidURIError: bad URI(is not URI?):
How can I safely pass a file name to URI that contains special characters? Why doesn't encode work on colon?
URI.escape (or encode) takes an optional second parameter. It's a Regexp matching all symbols that should be escaped. To escape all non-word characters you could use:
URI.encode('some filename with :colon in it.txt', /\W/)
#=> "some%20filename%20with%20%3Acolon%20in%20it%2Etxt"
There are two predefined regular expressions for encode:
URI::PATTERN::UNRESERVED #=> "\\-_.!~*'()a-zA-Z\\d"
URI::PATTERN::RESERVED #=> ";/?:#&=+$,\\[\\]"
require 'uri'
url = "file1:abc.txt"
p URI.encode_www_form_component url
--output:--
"file1%3Aabc.txt"
p URI(URI.encode_www_form_component url)
--output:--
#<URI::Generic:0x000001008abf28 URL:file1%3Aabc.txt>
p URI(URI.encode url, ":")
--output:--
#<URI::Generic:0x000001008abcd0 URL:file1%3Aabc.txt>
Why doesn't encode work on colon?
Because encode/escape is broken.
Use Addressable::URI::encode
require "addressable/uri"
a = 'some file name.txt'
Addressable::URI.encode(Addressable::URI.encode(a))
# => "some%2520file%2520name.txt"
b = 'some filename with :colon in it.txt'
Addressable::URI.encode(Addressable::URI.encode(b))
# => "some%2520filename%2520with%2520:colon%2520in%2520it.txt"
The problem seems to be the empty space preceding the colon, 'lol :lol.txt' don't work, but 'lol:lol.txt' works.
Maybe you could replace the spaces for something else.
If you want to escape special character from the given string. It is best to use
esc_uri=URI.escape("String with special character")
The result string is URI escaped string and safe to pass it to URI.
Refer URI::Escape for how to use URI escape. Hope this helps.

Regex in Ruby: expression not found

I'm having trouble with a regex in Ruby (on Rails). I'm relatively new to this.
The test string is:
http://www.xyz.com/017010830343?$ProdLarge$
I am trying to remove "$ProdLarge$". In other words, the $ signs and anything between.
My regular expression is:
\$\w+\$
Rubular says my expression is ok. http://rubular.com/r/NDDQxKVraK
But when I run my code, the app says it isn't finding a match. Code below:
some_array.each do |x|
logger.debug "scan #{x.scan('\$\w+\$')}"
logger.debug "String? #{x.instance_of?(String)}"
x.gsub!('\$\w+\$','scl=1')
...
My logger debug line shows a result of "[]". String is confirmed as being true. And the gsub line has no effect.
What do I need to correct?
Use /regex/ instead of 'regex':
> "http://www.xyz.com/017010830343?$ProdLarge$".gsub(/\$\w+\$/, 'scl=1')
=> "http://www.xyz.com/017010830343?scl=1"
Don't use a regex for this task, use a tool designed for it, URI. To remove the query:
require 'uri'
url = URI.parse('http://www.xyz.com/017010830343?$ProdLarge$')
url.query = nil
puts url.to_s
=> http://www.xyz.com/017010830343
To change to a different query use this instead of url.query = nil:
url.query = 'scl=1'
puts url.to_s
=> http://www.xyz.com/017010830343?scl=1
URI will automatically encode values if necessary, saving you the trouble. If you need even more URL management power, look at Addressable::URI.

Ruby/Rails 3.1: Given a URL string, remove path

Given any valid HTTP/HTTPS string, I would like to parse/transform it such that the end result is exactly the root of the string.
So given URLs:
http://foo.example.com:8080/whatsit/foo.bar?x=y
https://example.net/
I would like the results:
http://foo.example.com:8080/
https://example.net/
I found the documentation for URI::Parser not super approachable.
My initial, naïve solution would be a simple regex like:
/\A(https?:\/\/[^\/]+\/)/
(That is: Match up to the first slash after the protocol.)
Thoughts & solutions welcome. And apologies if this is a duplicate, but my search results weren't relevant.
With URI::join:
require 'uri'
url = "http://foo.example.com:8080/whatsit/foo.bar?x=y"
baseurl = URI.join(url, "/").to_s
#=> "http://foo.example.com:8080/"
Use URI.parse and then set the path to an empty string and the query to nil:
require 'uri'
uri = URI.parse('http://foo.example.com:8080/whatsit/foo.bar?x=y')
uri.path = ''
uri.query = nil
cleaned = uri.to_s # http://foo.example.com:8080
Now you have your cleaned up version in cleaned. Taking out what you don't want is sometimes easier than only grabbing what you need.
If you only do uri.query = '' you'll end up with http://foo.example.com:8080? which probably isn't what you want.
You could use uri.split() and then put the parts back together...
WARNING: It's a little sloppy.
url = "http://example.com:9001/over-nine-thousand"
parts = uri.split(url)
puts "%s://%s:%s" % [parts[0], parts[2], parts[3]]
=> "http://example.com:9001"

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