Question

How do I parse query strings safely in Dart?

Let’s assume I have q string with the value of:

?page=main&action=front&sid=h985jg9034gj498g859gh495

Ideally the code should work both in the server and client, but for now I’ll settle for a working client-side code.

Answer 1

I have made a simple package for that purpose exactly: https://github.com/kaisellgren/QueryString

Example:

import 'package:query_string/query_string.dart');

void main() {
  var q = '?page=main&action=front&sid=h985jg9034gj498g859gh495&enc=+Hello%20&empty';

  var r = QueryString.parse(q);

  print(r['page']); // "main"
  print(r['asdasd']); // null
}

The result is a Map. Accessing parameters is just a simple r['action'] and accessing a non-existant query parameter is null.

Now, to install, add to your pubspec.yaml as a dependency:

dependencies:
  query_string: any

And run pub install.

The library also handles decoding of things like %20 and +, and works even for empty parameters.

It does not support "array style parameters", because they are not part of the RFC 3986 specification.