parse static method

Map<String, Object?> parse(String query, { Encoding encoding = utf8, })

Parses a query string into a Map.

This method takes a query string and converts it into a map of key-value pairs. It supports URL decoding and handles array notation in keys (e.g., key[]=value1&key[]=value2).

Example:

var query = 'name=John&age=30&hobbies[]=reading&hobbies[]=writing';
var result = QueryString.parse(query);
print(result); // Outputs: {name: John, age: 30, hobbies: [reading, writing]}

query The query string to be parsed. It should be in the format of key=value&key2=value2.

encoding The encoding to be used for decoding the query components. Defaults to utf8.

Returns a Map where the keys are strings and the values are either strings or lists of strings, depending on whether the keys in the query string ended with [].

Implementation

static Map<String, Object?> parse(String query, {Encoding encoding = utf8}) {
  var result = <String, Object?>{};
  result = query.split("&").fold(
    {},
    (map, element) {
      int index = element.indexOf("=");
      if (index == -1) {
        if (element != "") {
          map[Uri.decodeQueryComponent(element, encoding: encoding)] = "";
        }
      } else if (index != 0) {
        var key = element.substring(0, index);
        var value = element.substring(index + 1);
        var encodeKey = Uri.decodeQueryComponent(key, encoding: encoding);
        var encodeValue = Uri.decodeQueryComponent(value, encoding: encoding);
        var isArray = encodeKey.endsWith('[]');

        if (isArray) {
          encodeKey = encodeKey.substring(0, encodeKey.length - 2);
          if (map.keys.contains(encodeKey)) {
            if (map[encodeKey] is List) {
              (map[encodeKey] as List).add(encodeValue);
            } else {
              var list = [];
              list.add(map[encodeKey]);
              list.add(encodeValue);
              map[encodeKey] = list;
            }
          } else {
            map[encodeKey] = [encodeValue];
          }
        } else {
          map[encodeKey] = encodeValue;
        }
      }
      return map;
    },
  );
  return result;
}