Replace Single Quotes With Double Quotes But Leave Ones Within Double Quotes Untouched

The ultimate goal or the origin of the problem is to have a field compatible with in json_extract_path_text Redshift. This is how it looks right now: {'error': 'Feed load failed: P

Solution 1:

Several ways, one is to use the regex module with

"[^"]*"(*SKIP)(*FAIL)|'

See a demo on regex101.com.

---

In Python:

import regex as re

rx = re.compile(r'"[^"]*"(*SKIP)(*FAIL)|\'')
new_string = rx.sub('"', old_string)

With the original re module, you'd need to use a function and see if the group has been matched or not - (*SKIP)(*FAIL) lets you avoid exactly that.

Solution 2:

I tried a regex approach but found it to complicated and slow. So i wrote a simple "bracket-parser" which keeps track of the current quotation mode. It can not do multiple nesting you'd need a stack for that. For my usecase converting str(dict) to proper JSON it works:

example input: {'cities': [{'name': "Upper Hell's Gate"}, {'name': "N'zeto"}]}

example output: {"cities": [{"name": "Upper Hell's Gate"}, {"name": "N'zeto"}]}'

python unit test

deftestSingleToDoubleQuote(self):
        jsonStr='''
        {
            "cities": [
            {
                "name": "Upper Hell's Gate"
            },
            {
                 "name": "N'zeto"
            }
            ]
        }
        '''
        listOfDicts=json.loads(jsonStr)
        dictStr=str(listOfDicts)   
        if self.debug:
            print(dictStr)
        jsonStr2=JSONAble.singleQuoteToDoubleQuote(dictStr)
        if self.debug:
            print(jsonStr2)
        self.assertEqual('''{"cities": [{"name": "Upper Hell's Gate"}, {"name": "N'zeto"}]}''',jsonStr2)

singleQuoteToDoubleQuote

defsingleQuoteToDoubleQuote(singleQuoted):
            '''
            convert a single quoted string to a double quoted one
            Args:
                singleQuoted(string): a single quoted string e.g. {'cities': [{'name': "Upper Hell's Gate"}]}
            Returns:
                string: the double quoted version of the string e.g. 
            see
               - https://stackoverflow.com/questions/55600788/python-replace-single-quotes-with-double-quotes-but-leave-ones-within-double-q 
            '''
            cList=list(singleQuoted)
            inDouble=False;
            inSingle=False;
            for i,c inenumerate(cList):
                #print ("%d:%s %r %r" %(i,c,inSingle,inDouble))if c=="'":
                    ifnot inDouble:
                        inSingle=not inSingle
                        cList[i]='"'elif c=='"':
                    inDouble=not inDouble
            doubleQuoted="".join(cList)    
            return doubleQuoted