Question

I have grails app that makes a REST call. If an error occurs, a JSON array containing the error messages is returned. I need to combine these strings into a single string. However, when I do so double quotes are added to the front and end of the string. I have written a simple test controller to illustrate the problem:

import net.sf.json.*
class MyController {

    def test = {

        String msg = "'fred' is not a valid LDAP distinguished name."
        JSONArray messages = new JSONArray()
        messages.add(msg)
        def renderStr = messages.join('<br/>')

        render(renderStr)
    }
}

The output looks like this:

"'fred' is not a valid LDAP distinguished name."

Answer 1

The problem is that the join function returns JSON-spec strings… which, according to their documentation here: http://grails.org/doc/1.0.3/api/org/codehaus/groovy/grails/web/json/JSONArray.html

 The texts produced by the toString methods strictly conform to JSON syntax rules. The constructors are more forgiving in the texts they will accept:

    An extra , (comma) may appear just before the closing bracket.
    The null value will be inserted when there is , (comma) elision.
    Strings may be quoted with ' (single quote).
    Strings do not need to be quoted at all if they do not begin with a quote or single quote, and if they do not contain leading or trailing spaces, and if they do not contain any of these characters: { } [ ] / \ : , = ; # and if they do not look like numbers and if they are not the reserved words true, false, or null.
    Values can be separated by ; (semicolon) as well as by , (comma).
    Numbers may have the 0- (octal) or 0x- (hex) prefix.
    Comments written in the slashshlash, slashstar, and hash conventions will be ignored.

Note that the rule that “Strings do not need to be quoted at all if they do not begin with a quote or single quote” is what’s happening. Your string starts with a quote, so if it was output without quotes, a JSON parser would assume the string ended at the 2nd single-quote, and the text afterwards would be unparseable garbage.