This is what happens when I try to use a colon in th:text:
and a backslash doesn't seem to fix it:
How can I use the colon symbol in th:text?
If you want to place a literal into th:text, you have to use single quotes: th:text="'7:00AM'". See documentation here.
(By contrast, something like this th:text="7_00AM" is valid - because it is a literal token. Such strings can only use a subset of characters, but do not need enclosing 's.)
Related
I have read the answer to this similar question: Do I need quotes for strings in YAML?
However, there was no answer for whether we can escape quotes with strings containing forward slashes /.
For example, do we need to add quotes to the following eslint rule 'react/no-deprecated': off?
No, / is not a special character in YAML. YAML allows the escape sequence \/ in double-quoted scalars to resolve to / for JSON compatibility, but there is no requirement to use this escape sequence and no requirement to use quotes at all to use / as content character.
I am using the following code to check if a string contains an apostrophe:
string.scan(/’|'/)
I have included two types of single quotation because I found that using just the standard ' did not catch some strings that contain an apostrophe using the ’
My concern is that if I am checking strings that may contain other fonts or styles my regex won't catch the apostrophe.
Is there a more general approach that would catch all forms of an apostrophe?
Straight single quote is the generic vertical quotation marks:
straight single quote (')
Curly quotes are the quotation marks used in good typography. There are two curly single quote characters:
the opening single quote (‘)
the closing single quote (’)
Going by the above three variants:
You maytry this:
string.scan(/['‘’]/)
Those would probably be the most common ones :
/[‘’']/
If you just need to check if a string contains a regex, you shouldn't use scan :
"apostrophe's" =~ /[‘’']/ #=> 10
=~ will stop at the first match.
Why doesn't URI.escape escape single quotes?
URI.escape("foo'bar\" baz")
=> "foo'bar%22%20baz"
For the same reason it doesn't escape ? or / or :, and so forth. URI.escape() only escapes characters that cannot be used in URLs at all, not characters that have a special meaning.
What you're looking for is CGI.escape():
require "cgi"
CGI.escape("foo'bar\" baz")
=> "foo%27bar%22+baz"
This is an old question, but the answer hasn't been updated in a long time. I thought I'd update this for others who are having the same problem. The solution I found was posted here: use ERB::Util.url_encode if you have the erb module available. This took care of single quotes & * for me as well.
CGI::escape doesn't escape spaces correctly (%20) versus plus signs.
According to the docs, URI.escape(str [, unsafe]) uses a regexp that matches all symbols that must be replaced with codes. By default the method uses REGEXP::UNSAFE. When this argument is a String, it represents a character set.
In your case, to modify URI.escape to escape even the single quotes you can do something like this ...
reserved_characters = /[^a-zA-Z0-9\-\.\_\~]/
URI.escape(YOUR_STRING, reserved_characters)
Explanation: Some info on the spec ...
All parameter names and values are escaped using the [rfc3986]
percent- encoding (%xx) mechanism. Characters not in the unreserved
character set ([rfc3986] section 2.3) must be encoded. characters in
the unreserved character set must not be encoded. hexadecimal
characters in encodings must be upper case. text names and values must
be encoded as utf-8 octets before percent-encoding them per [rfc3629].
I know this has been answered, but what I wanted was something slightly different, and I thought I might as well post it up: I wanted to keep the "/" in the url, but escape all the other non-standard characters. I did it thus:
#public filename is a *nix filepath,
#like `"/images/isn't/this a /horrible filepath/hello.png"`
public_filename.split("/").collect{|s| ERB::Util.url_encode(s)}.join("/")
=> "/images/isn%27t/this%20a%20/horrible%20filepath/hello.png"
I needed to escape the single quote as I was writing a cache invalidation for AWS Cloudfront, which didn't like the single quotes and expected them to be escaped. The above should make a uri which is more safe than the standard URI.escape but which still looks like a URI (CGI Escape breaks the uri format by escaping "/").
How do I excape a backslash before a captured group?
Example:
"foo+bar".gsub(/(\+)/, '\\\1')
What I expect (and want):
foo\+bar
what I unfortunately get:
foo\\1bar
How do I escape here correctly?
As others have said, you need to escape everything in that string twice. So in your case the solution is to use '\\\\\1' or '\\\\\\1'. But since you asked why, I'll try to explain that part.
The reason is that replacement sequence is being parsed twice--once by Ruby and once by the underlying regular expression engine, for whom \1 is its own escape sequence. (It's probably easier to understand with double-quoted strings, since single quotes introduce an ambiguity where '\\1' and '\1' are equivalent but '\' and '\\' are not.)
So for example, a simple replacement here with a captured group and a double quoted string would be:
"foo+bar".gsub(/(\+)/, "\\1") #=> "foo+bar"
This passes the string \1 to the regexp engine, which it understands as a reference to a capture group. In Ruby string literals, "\1" means something else entirely (ASCII character 1).
What we actually want in this case is for the regexp engine to receive \\\1. It also understands \ as an escape character, so \\1 is not sufficient and will simply evaluate to the literal output \1. So, we need \\\1 in the regexp engine, but to get to that point we need to also make it past Ruby's string literal parser.
To do that, we take our desired regexp input and double every backslash again to get through Ruby's string literal parser. \\\1 therefore requires "\\\\\\1". In the case of single quotes one slash can be omitted as \1 is not a valid escape sequence in single quotes and is treated literally.
Addendum
One of the reasons this problem is usually hidden is thanks to the use of /.+/ style regexp quotes, which Ruby treats in a special way to avoid the need to double escape everything. (Of course, this doesn't apply to gsub replacement strings.) But you can still see it in action if you use a string literal instead of a regexp literal in Regexp.new:
Regexp.new("\.").match("a") #=> #<MatchData "a">
Regexp.new("\\.").match("a") #=> nil
As you can see, we had to double-escape the . for it to be understood as a literal . by the regexp engine, since "." and "\." both evaluate to . in double-quoted strings, but we need the engine itself to receive \..
This happens due to a double string escaping. You should use 5 slashes in this case.
"foo+bar".gsub(/([+])/, '\\\\\1')
Adding \ two more times escapes this properly.
irb(main):011:0> puts "foo+bar".gsub(/(\+)/, '\\\\\1')
foo\+bar
=> nil
Usually when my regex patterns look like this:
http://www.microsoft.com/
Then i have to escape it like this:
string.match(/http:\/\/www\.microsoft\.com\//)
Is there another way instead of escaping it like that?
I want to be able to just use it like this http://www.microsoft.com, cause I don't want to escape all the special characters in all my patterns.
Regexp.new(Regexp.quote('http://www.microsoft.com/'))
Regexp.quote simply escapes any characters that have special regexp meaning; it takes and returns a string. Note that . is also special. After quoting, you can append to the regexp as needed before passing to the constructor. A simple example:
Regexp.new(Regexp.quote('http://www.microsoft.com/') + '(.*)')
This adds a capturing group for the rest of the path.
You can also use arbitrary delimiters in Ruby for regular expressions by using %r and defining a character before the regular expression, for example:
%r!http://www.microsoft.com/!
Regexp.quote or Regexp.escape can be used to automatically escape things for you:
https://ruby-doc.org/core/Regexp.html#method-c-escape
The result can be passed to Regexp.new to create a Regexp object, and then you can call the object's .match method and pass it the string to match against (the opposite order from string.match(/regex/)).
You can simply use single quotes for escaping.
string.match('http://www.microsoft.com/')
you can also use %q{} if you need single quotes in the text itself. If you need to have variables extrapolated inside the string, then use %Q{}. That's equivalent to double quotes ".
If the string contains regex expressions (eg: .*?()[]^$) that you want extrapolated, use // or %r{}
For convenience I just define
def regexcape(s)
Regexp.new(Regexp.escape(s))
end