I've got a sinatra app where I plan to make a friedly-urls on the fly. I've got a function with a regexp that looks like this, but it won't turn 'spaces' into 'dashes', ' ' to '-'.
def self.make_slug(title)
title.downcase.gsub(/ /, '-').gsub(/[^a-z0-9_]/, '').squeeze('-')
end
Thanks in advance!
Update
Now I'm also trying to change åä into a and ö into o, my code looks like this but won't work, any ideas?
gsub(/[åä]/, 'a')
gsub(/[ö]/, 'o')
title.downcase.gsub(/\s+/, '-').gsub(/[^a-z0-9_-]/, '').squeeze('-')
This will take a given title (My & Title5:) and:
* downcase it (my & title5:)
* replace one or more white space characters with a - (my-&-title5:)
* replace non letters/number characters with nothing (my--title5)
* replace multiple occurrences of - with - (my-title5)
I hope this helps.
Whatever the language, you're first replacing " " with "-", and then replace everything but a-z0-9_ (thus, also "-") with "". Include "-" in the list like [^a-z0-9_-]
Related
I have a string like this:
"<root><some ProdCode=\"40\" ProducerName=\"demo1\" ProdCode=\"40\" Need_Confirmation=\"1\"/><some ProdCode=\"40\" ProducerName=\"demo1\" ProdCode=\"40\" Need_Confirmation=\"1\"/></root>"
I'm trying to pull the content from this string which is between =\"content\" and put it in an array, like ["40","demo1","40","1",40......]
You should use :scan to select elements by regexp pattern. Then remove escape characters.
string.scan(/"[^"]+"/).map { |element| element.delete('\\"') }
Explanation of pattern:
/ – regexp starts
" – first char should be "
[^"]+ – next should be any char except ". + sign says that number of such chars should be at least 1.
" – next should be again "
/ – regexp ends
So string.scan(/"[^"]+"/) would return:
["\"40\"", "\"demo1\"", "\"40\"", "\"1\"", "\"40\"", "\"demo1\"", "\"40\"", "\"1\""]
Then we can just delete \" using :delete method.
Convenient tool to build regexps is http://rubular.com/
When your string is this simple you can use scan + regular expression like this:
result = html.scan(/ProdCode="\d+?"/)
If it is more complex you can use a html parser like nokogiri or oga.
I have the following string -
abcdefgh;
lmnopqrst;
On doing a string = string.split(";"), I get -
["abcdefgh", "\nlmnopqrst"]
Now when I do -
string[1].start_with?("\\")
The function returns false. Whereas if I do
string[0].start_with?("a")
The function return true.
I am new to ruby and just can't understand this behavior. Can anyone tell me what am I doing wrong.
I dont know, butString[1][0] (first character from string) returns "\n" so maybe use this
string[1].start_with?("\n")
This is because "\n" actually does not start with a backslash . It is the line feed character and is considered to be a single character and for that reason it is only presented having the escape character \ in front of it.
So:
string[1].start_with?("\n")
Will return true.
You already tried to search with string[1].start_with?("\\") so you seem to realize you need to escape the backslash character by using \\.
If your input string would look like this:
\abcdefgh;
lmnopqrst;
Then after .split(';') your resulting array would look like this:
["\\abcdefgh;", "\nlmnopqrst"]
Now string[0].start_with?("\\") would return true because the first string actually starts with a single backslash, which was presented with the escape character in the console.
you can try
'\nhello world'.start_with?("\\") # return true
"\nhello world".start_with?("\\") # return false
because '\n' is two chars( \ and n), but "\n" is one char(new line char).
The first character there is not "\" - it's "\n" in the first example, and "\\" in the second. "\n" and "\\" are effectively single characters in this context, even though they look like two characters.
"\n" != "\\", and so start_with? responds false.
I'm trying to reformat German dates (e.g. 13.03.2011 to 2011-03-13).
This is my code:
str = "13.03.2011\n14:30\n\nHannover Scorpions\n\nDEG Metro Stars\n60\n2 - 3\n\n\n\n13.03.2011\n14:30\n\nThomas Sabo Ice Tigers\n\nKrefeld Pinguine\n60\n2 - 3\n\n\n\n"
str = str.gsub("/(\d{2}).(\d{2}).(\d{4})/", "/$3-$2-$1/")
I get the same output like input. I also tried my code with and without leading and ending slashes, but I don't see a difference. Any hints?
I tried to store my regex'es in variables like find = /(\d{2}).(\d{2}).(\d{4})/ and replace = /$3-$2-$1/, so my code looked like this:
str = "13.03.2011\n14:30\n\nHannover Scorpions\n\nDEG Metro Stars\n60\n2 - 3\n\n\n\n13.03.2011\n14:30\n\nThomas Sabo Ice Tigers\n\nKrefeld Pinguine\n60\n2 - 3\n\n\n\n"
find = /(\d{2}).(\d{2}).(\d{4})/
replace = /$3-$2-$1/
str = str.gsub(find, replace)
TypeError: no implicit conversion of Regexp into String
from (irb):4:in `gsub'
Any suggestions for this problem?
First mistake is the regex delimiter. You do not need place the regex as string. Just place it inside a delimiter like //
Second mistake, you are using captured groups as $1. Replace those as \\1
str = str.gsub(/(\d{2})\.(\d{2})\.(\d{4})/, "\\3-\\2-\\1")
Also, notice I have escaped the . character with \., because in regex . means any character except \n
I was doing the challenges from pythonchallenge writing code in ruby, specifically this one. It contains a really long string in page source with special characters. I was trying to find a way to delete them/check for the alphabetical chars.
I tried using scan method, but I think I might not use it properly. I also tried delete! like that:
a = "PAGE SOURCE CODE PASTED HERE"
a.delete! "!", "#" #and so on with special chars, does not work(?)
a
How can I do that?
Thanks
You can do this
a.gsub!(/[^0-9A-Za-z]/, '')
try with gsub
a.gsub!(/[!#%&"]/,'')
try the regexp on rubular.com
if you want something more general you can have a string with valid chars and remove what's not in there:
a.gsub!(/[^abcdefghijklmnopqrstuvwxyz ]/,'')
When you give multiple arguments to string#delete, it's the intersection of those arguments that is deleted. a.delete! "!", "#" deletes the intersections of the sets ! and # which means that nothing will be deleted and the method returns nil.
What you wanted to do is a.delete! "!#" with the characters to delete passed as a single string.
Since the challenge is asking to clean up the mess and find a message in it, I would go with a whitelist instead of deleting special characters. The delete method accepts ranges with - and negations with ^ (similar to a regex) so you can do something like this: a.delete! "^A-Za-z ".
You could also use regular expressions as shown by #arieljuod.
gsub is one of the most used Ruby methods in the wild.
specialname="Hello!#$#"
cleanedname = specialname.gsub(/[^a-zA-Z0-9\-]/,"")
I think a.gsub(/[^A-Za-z0-9 ]/, '') works better in this case. Otherwise, if you have a sentence, which typically should start with a capital letter, you will lose your capital letter. You would also lose any 1337 speak, or other possible crypts within the text.
Case in point:
phrase = "Joe can't tell between 'large' and large."
=> "Joe can't tell between 'large' and large."
phrase.gsub(/[^a-z ]/, '')
=> "oe cant tell between large and large"
phrase.gsub(/[^A-Za-z0-9 ]/, '')
=> "Joe cant tell between large and large"
phrase2 = "W3 a11 f10a7 d0wn h3r3!"
phrase2.gsub(/[^a-z ]/, '')
=> " a fa dwn hr"
phrase2.gsub(/[^A-Za-z0-9 ]/, '')
=> "W3 a11 f10a7 d0wn h3r3"
If you don't want to change the original string - i.e. to solve the challenge.
str.each_char do |letter|
if letter =~ /[a-z]/
p letter
end
end
You will have to write down your own string sanitize function, could easily use regex and the gsub method.
Atomic sample:
your_text.gsub!(/[!#\[;\]^%*\(\);\-_\/&\\|$\{#\}<>:`~"]/,'')
API sample:
Route: post 'api/sanitize_text', to: 'api#sanitize_text'
Controller:
def sanitize_text
return render_bad_request unless params[:text].present? && params[:text].present?
sanitized_text = params[:text].gsub!(/[!#\[;\]^%*\(\);\-_\/&\\|$\{#\}<>:`~"]/,'')
render_response( {safe_text: sanitized_text})
end
Then you call it
POST /api/sanitize_text?text=abcdefghijklmnopqrstuvwxyz123456<>$!#%23^%26*[]:;{}()`,.~'"\|/
I am trying to write a method that is the same as mysqli_real_escape_string in PHP. It takes a string and escapes any 'dangerous' characters. I have looked for a method that will do this for me but I cannot find one. So I am trying to write one on my own.
This is what I have so far (I tested the pattern at Rubular.com and it worked):
# Finds the following characters and escapes them by preceding them with a backslash. Characters: ' " . * / \ -
def escape_characters_in_string(string)
pattern = %r{ (\'|\"|\.|\*|\/|\-|\\) }
string.gsub(pattern, '\\\0') # <-- Trying to take the currently found match and add a \ before it I have no idea how to do that).
end
And I am using start_string as the string I want to change, and correct_string as what I want start_string to turn into:
start_string = %("My" 'name' *is* -john- .doe. /ok?/ C:\\Drive)
correct_string = %(\"My\" \'name\' \*is\* \-john\- \.doe\. \/ok?\/ C:\\\\Drive)
Can somebody try and help me determine why I am not getting my desired output (correct_string) or tell me where I can find a method that does this, or even better tell me both? Thanks a lot!
Your pattern isn't defined correctly in your example. This is as close as I can get to your desired output.
Output
"\\\"My\\\" \\'name\\' \\*is\\* \\-john\\- \\.doe\\. \\/ok?\\/ C:\\\\Drive"
It's going to take some tweaking on your part to get it 100% but at least you can see your pattern in action now.
def self.escape_characters_in_string(string)
pattern = /(\'|\"|\.|\*|\/|\-|\\)/
string.gsub(pattern){|match|"\\" + match} # <-- Trying to take the currently found match and add a \ before it I have no idea how to do that).
end
I have changed above function like this:
def self.escape_characters_in_string(string)
pattern = /(\'|\"|\.|\*|\/|\-|\\|\)|\$|\+|\(|\^|\?|\!|\~|\`)/
string.gsub(pattern){|match|"\\" + match}
end
This is working great for regex
This should get you started:
print %("'*-.).gsub(/["'*.-]/){ |s| '\\' + s }
\"\'\*\-\.
Take a look at the ActiveRecord sanitization methods: http://api.rubyonrails.org/classes/ActiveRecord/Base.html#method-c-sanitize_sql_array
Take a look at escape_string / quote method in Mysql class here