Hi I'm creating a regular expression (ruby) to test the beginning and end of string. I have both parts but can't join them.
Beginning of string
\A(http:\/\/+)
End of string
(.pdf)\z
How to join?
Bonus if it could validate in-between and accept anything (to avoid http://.pdf)
By the way, rubular http://rubular.com is a neat place to validate expressions
Use .+ to match any character except \n one or more times.
\A(http:\/\/+).+(\.pdf)\z
Should match http://www.stackoverflow.com/bestbook.pdf but not http://.pdf
Related
I am building a Rails 5.2 app.
In this app I got outputs from different suppliers (I am building a webshop).
The name of the shipping provider is in this format:
dhl_freight__233433
It could also be in this format:
postal__US-320202
How can I remove all that is before (and including) the __ so all that remains are the things after the ___ like for example 233433.
Perhaps some sort of RegEx.
A very simple approach would be to use String#split and then pick the second part that is the last part in this example:
"dhl_freight__233433".split('__').last
#=> "233433"
"postal__US-320202".split('__').last
#=> "US-320202"
You can use a very simple Regexp and a ask the resulting MatchData for the post_match part:
p "dhl_freight__233433".match(/__/).post_match
# another (magic) way to acces the post_match part:
p $'
Postscript: Learnt something from this question myself: you don't even have to use a RegExp for this to work. Just "asddfg__qwer".match("__").post_match does the trick (it does the conversion to regexp for you)
r = /[^_]+\z/
"dhl_freight__233433"[r] #=> "233433"
"postal__US-320202"[r] #=> "US-320202"
The regular expression matches one or more characters other than an underscore, followed by the end of the string (\z). The ^ at the beginning of the character class reads, "other than any of the characters that follow".
See String#[].
This assumes that the last underscore is preceded by an underscore. If the last underscore is not preceded by an underscore, in which case there should be no match, add a positive lookbehind:
r = /(?<=__[^_]+\z/
This requires the match to be preceded by two underscores.
There are many ruby ways to extract numbers from string. I hope you're trying to fetch numbers out of a string. Here are some of the ways to do so.
Ref- http://www.ruby-forum.com/topic/125709
line.delete("^0-9")
line.scan(/\d/).join('')
line.tr("^0-9", '')
In the above delete is the fastest to trim numbers out of strings.
All of above extracts numbers from string and joins them. If a string is like this "String-with-67829___numbers-09764" outut would be like this "6782909764"
In case if you want the numbers split like this ["67829", "09764"]
line.split(/[^\d]/).reject { |c| c.empty? }
Hope these answers help you! Happy coding :-)
For my ruby on rails project, I have a model called message which has a to field. I want to implement a wildcard search so that, for example, %545 will bring up all messages ending with 545, 545% will bring up all numbers starting with 545, %545% will bring up all messages including 545.
I have a query like Message.where("to like ?", str) where str is the string to match, e.g. %545, %545%, 545%...etc.
Everything works but I'm concerned about SQL injection attack. So I want to do a regex matching for str so that it only allows % and numbers to pass through. So I want strings like %545, %545%, 545% to pass, but not abc, %545a, a545%, %54a5% to pass.
I've tried str.scan(/.*?(\d+%)/) but that doesn't work.
Thanks.
You are correctly using placeholders, so you are protected from SQL injection attacks already. Rails will escape any unsafe characters in the pattern; you don't need to take any further action.
If you still want to strip characters other than digits and %, you can use Ruby's String#delete method:
str.delete('^1-9%')
The '^1-9%' argument means "Delete every character that is not 1 to 9 or %". (n.b. you cannot use \d here, because #delete doesn't understand regular expression meta characters.)
See https://ruby-doc.org/core-2.5.3/String.html#method-i-delete.
So, I am trying to apply regular expression to email addresses coming into a site I am working on to try and verify that they are mostly valid. The regular expression is the one below.
[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#
(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])
When put into ruby as below.
if email =~ [a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*# (?:[a-z0-9]
(?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])
#logic here if regex passes
end
The problem is that the regular expression below contains '#' characters which are understood as comments in ruby. So, is there a way to use the regular expression without the '#' being interpreted as comments? Can regular expression be stored as strings or something similar?
You have to use ruby regex syntax /regex/, or build new regexp with Regexp.new(string)
regexp = /[a-z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+\/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])/
if email =~ regexp
#logic here if regex passes
end
I have a string from which I want to extract a certain part:
Original String: /abc/d7_t/g-12/jkl/m-n3/pqr/stu/vwx
Result Desired: /abc/d7_t/g-12/jkl/
The number of characters can vary in the entire string. It has alphabets, numbers, underscore and hyphen. I want to basically cut the string after the 5th "/"
I tried a few regex, but it seems there is some mistake with the format.
If a non-regexp approach is acceptable, how about this:
s.split('/').take(n).join('/')+'/'
Where s if your string (in your case: /abc/d7_t/g-12/jkl/m-n3/pqr/stu/vwx).
def cut_after(s, n)
s.split('/').take(n).join('/')+'/'
end
Then
cut_after("/abc/d7_t/g-12/jkl/m-n3/pqr/stu/vwx", 5)
should work. Not as compact as a regexp, but some people may find it clearer.
The regexp would be: %r(/(?:[^/]+/){4}). Note that it is a good idea in this case to use the %r literal version to avoid escaping slashes. Unescaped slashes are likely the cause of your format errors.
Match any sequence of chars except '/' 4 times :-
(\/[^\/]+){4}\/
I would like to use regular expression to check if my string have the format like following:
mc_834faisd88979asdfas8897asff8790ds_oa_ids
mc_834fappsd58979asdfas8897asdf879ds_oa_ids
mc_834faispd8fs9asaas4897asdsaf879ds_oa_ids
mc_834faisd8dfa979asdfaspo97asf879ds_dv_ids
mc_834faisd111979asdfas88mp7asf879ds_dv_ids
mc_834fais00979asdfas8897asf87ggg9ds_dv_ids
The format is like mc_<random string>_oa_ids or mc_<random string>_dv_ids . How can I check if my string is in either of these two formats? And please explain the regular expression. thank you.
That's a string start with mc_, while end with _oa_ids or dv_ids, and have some random string in the middle.
P.S. the random string consists of alpha-beta letters and numbers.
What I tried(I have no clue how to check the random string):
/^mc_834faisd88979asdfas8897asff8790ds$_os_ids/
Try this.
^mc_[0-9a-z]+_(dv|oa)_ids$
^ matches at the start of the line the regex pattern is applied to.
[0-9a-z] matces alphabetic and numeric chars.
+ means that there should be one or more chars in this set
(dv|oa) matches dv or oa
$ matches at the end of the string the regex pattern is applied to.
also matches before the very last line break if the string ends with a line break.
Give /\Amc_\w*_(oa|dv)_ids\z/ a try. \A is the beginning of the string, \z the end. \w* are one or more of letters, numbers and underscores and (oa|dv) is either oa or dv.
A nice and simple way to test Ruby Regexps is Rubular, might have a look at it.
This should work
/mc_834([a-z,0-9]*)_(oa|dv)_ids/g
Example: http://regexr.com?2v9q7