How do you add query parameters to a Dart http request?

If you dont want to override the scheme of base endpoint url, use the below technique to convert the map to query string and append it to the base endpoint url

var endpointUrl = 'https://www.myurl.com/api/v1/user';
Map<String, String> queryParams = {
  'param1': '1',
  'param2': '2'
};

var headers = {
  HttpHeaders.authorizationHeader: 'Token $token',
  HttpHeaders.contentTypeHeader: 'application/json',
}

String queryString = Uri.parse(queryParameters: queryParams).query;

var requestUrl = endpointUrl + '?' + queryString; // result - https://www.myurl.com/api/v1/user?param1=1&param2=2
var response = await http.get(requestUrl, headers: headers);

You'll want to construct a Uri and use that for the request. Something like

final queryParameters = {
  'param1': 'one',
  'param2': 'two',
};
final uri =
    Uri.https('www.myurl.com', '/api/v1/test/${widget.pk}', queryParameters);
final response = await http.get(uri, headers: {
  HttpHeaders.authorizationHeader: 'Token $token',
  HttpHeaders.contentTypeHeader: 'application/json',
});

See https://api.dartlang.org/stable/2.0.0/dart-core/Uri/Uri.https.html

this is more simple

final uri = Uri.parse('$baseUrl/v1/endpoint').replace(queryParameters: {
      'page': page,
      'itemsPerPage': itemsPerPage,
    });
final response = await client.get(uri);