How do I do a case insensitive regular expression in Go?

You can set a case-insensitive flag as the first item in the regex.

You do this by adding "(?i)" to the beginning of a regex.

reg, err := regexp.Compile("(?i)"+strings.Replace(s.Name, " ", "[ \\._-]", -1))

For a fixed regex it would look like this.

r := regexp.MustCompile(`(?i)CaSe`)

For more information about flags, search the regexp/syntax package documentation (or the syntax documentation) for the term "flags".

Use the i flag. Quoting the tip documentation:

Grouping:

(re)           numbered capturing group
(?P<name>re)   named & numbered capturing group
(?:re)         non-capturing group
(?flags)       set flags within current group; non-capturing
(?flags:re)    set flags during re; non-capturing

Flag syntax is xyz (set) or -xyz (clear) or xy-z (set xy, clear z). The flags are:

i              case-insensitive (default false)
m              multi-line mode: ^ and $ match begin/end line in addition to begin/end text (default false)
s              let . match \n (default false)
U              ungreedy: swap meaning of x* and x*?, x+ and x+?, etc (default false)

I'm not too familiar with Go, but according to this example: http://play.golang.org/p/WgpNhwWWuW

You need to prefix your regex statement with (?i)

You can add a (?i) at the beginning of the pattern to make it case insensitive.

Reference