Parse JSON String By Comma Deliminator Flutter - json

Question

I have some string that I need to separate into Latitude and Longitude to get LatLng but, do not know how to separate by delimiter to pull it off.
The string is: {location: 40.748817,-73.985428}
I need to separate it into Lat and lng to create a marker and do not know how

Answer 1

Try this !
//If String
String location = 'location: 40.748817,-73.985428';
List<String> latAndLong =
location.replaceFirst(' ', '').replaceAll('location:', '').split(',');
LatLng latLng = new LatLng(double.parse(latAndLong[0]),double.parse(latAndLong[1]));
//If Map/JSON
var location2 = {'location': '40.748817,-73.985428'};
String locationExtracted = location2['location'].toString();
List<String> latAndLong2 =
locationExtracted.replaceFirst(' ', '').replaceAll('location:', '').split(',');
LatLng latLng2 = new LatLng(double.parse(latAndLong2[0]),double.parse(latAndLong2[1]));

Answer 2

Depending on what the actual input format is, it can be easier or harder.
If the input is actually a JSON map with the format {"location": "40.748817,-73.985428"}, then just parse it as JSON first, then split the string on the comma:
List<double> parseCoordinates(String source) {
var parts = jsonParse(source)["location"]?.split(",");
if (parts == null || parts.length != 2) {
throw FormatException("Not valid location coordinates", source);
}
return [double.parse(parts[0], double.parts[1])];
}
If the input is actually a string of the form {location: 40.748817,-73.985428}, which is not valid JSON, then it looks like something which is actually most easily solved with a RegExp.
Example:
final _coordRE = RegExp(r"^\{location: (-?\d+(?:.\d+)), (-?\d+(?:.\d+))\}$");
List<double> parseCoordinates2(String source) {
var match = _coordRE.firstMatch(source);
if (match == null) throw FormatException("Not valid coordinates", source);
return [double.parse(match[1]), double.parse(match[2])];
}
and then use it as
var coords = parseCoordinates(source);
var lat = coords[0];
var lng = coords[1];
Alternatively, since you know the format so precisely, you can just extract the substrings yourself instead of using a RegExp:
List<double> parseCoordinates(String source) {
var prefix = "{location: ";
if (source.startsWith(prefix) && source.endsWith("}")) {
var commaIndex = source.indexOf(",", prefix.length);
if (commaIndex >= 0) {
var lat = double.parse(source.substring(prefix.length, commaIndex));
var lng = double.parse(source.substring(commaIndex + 1, source.length - 1));
return [lat, lng];
}
}
throw FormatException("Not valid coordinates", source);
}
If the format can vary more than your example (perhaps it allows -.5 as a coordinate, with no leading 0), you'll have to adapt the regexp. One option is to have the capture groups simply capture [-.\d]+ and rely on the double parser to handle syntax errors.

Answer 3

Have you tried the function jsonDecode? It returns a dynamic.
var coordinate = jsonDecode('[your json string]');
print(coordinate['location']);
Then the rest is just to split it into tokens with split() function.
G'luck.