How do I escape a single quote in Ruby?

I am passing some JSON to a server via a script (not mine) that accepts the JSON as a string.

Some of the content of the JSON contains single quotes so I want to ensure that any single quotes are escaped before being passed to the script.

I have tried the following:

> irb
> 1.9.3p194 :001 > x = "that's an awesome string"
> => "that's an awesome string"
> 1.9.3p194 :002 > x.sub("'", "\'")
> => "that's an awesome string"
> 1.9.3p194 :003 > x.sub("'", "\\'")
> => "thats an awesome strings an awesome string"

but can't seem to get the syntax right.

Try this way, use backslash to escape:

puts 'sean\'s'

output should be:

sean's

It's likely that if you are trying to escape a single quote (apostrophe), you want to also escape double quotes. (This would apply for Javascript/JSON)

The easiest way is to use `escape_javascript`

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it "Escapes carriage returns and single and double quotes for JavaScript segments."

NOTE this works only for **Ruby on Rails**, not plain Ruby. However you can make a polyfill for plain Ruby using something like this:


JS_ESCAPE_MAP = { '\\' => '\\\\', '</' => '<\/', "\r\n" => '\n', "\n" => '\n', "\r" => '\n', '"' => '\\"', "'" => "\\'" }

def escape_javascript(javascript)
if javascript
result = javascript.gsub(/(\|<\/|\r\n|\342\200\250|\342\200\251|[\n\r"'])/u) {|match| JS_ESCAPE_MAP[match] }
else
''
end
end

The reason `sub("'", "\'")` does not work is because `"\'"` is the same as `"'"`. Within double quotes, escaping of a single quote is optional.

The reason `sub("'", "\\'")` does not work is because `"\\'"` expands to a backslash followed by a single quote. Within `sub` or `gsub` argument, a backslash followed by some characters have special meaning comparable to the corresponding global variable. Particularly in this case, the global variable `$'` holds the substring after the last matching point. Your `"\\'"` within `sub` or `gsub` argument position refers to a similar thing. In order to avoid this special convention, you should put the replacement string in a block instead of an argument, and since you want to match not just one, you should use `gsub` instead of `sub`:

gsub("'"){"\\'"}

Why aren't you using the JSON gem?

require 'json'
some_object = {'a string' => "this isn't escaped because JSON handles it.", 'b' => 2}

puts some_object.to_json
=> {"a string":"this isn't escaped because JSON handles it.","b":2}

And a round-trip example:

require 'pp'
pp JSON[some_object.to_json]
=> {
"a string" => "this isn't escaped because JSON handles it.",
"b" => 2
}

And an example with double-quotes:

some_object = {
'a string' => "this isn't escaped because JSON handles it.",
'another string' => 'double-quotes get "escaped"'
}
puts some_object.to_json
=> {
"a string" => "this isn't escaped because JSON handles it.",
"another string" => "double-quotes get \"escaped\""
}