urldat function Null safety

String urldat(
  1. String base,
  2. String pathOrTemplate,
  3. {Map<String, dynamic>? parameters,
  4. String? scheme,
  5. int? port,
  6. String? fragment}

Function that takes base string URL and pathOrTemplate string URL. pathOrTemplate can be either:

  • path segment like /path/to/something
  • or path segment template like /users/:id/comments/

If parameters map is provided, the template keys in pathOrTemplate are substituted with the values from parameters. Extra keys in parameters that do not map to pathOrTemplate are always used as query parameters.

If pathOrTemplate is template (contains :colon) and no parameters are provided, UrldatError exception will be thrown.

scheme option is a valid URI scheme. It's intended to be used with base URL when no scheme is present in it. Warning: Function will throw UrldatError when base path contains scheme already.

port option is a integer describing the port number, zero or 80 are ignored in the final URL

fragment option will append fragment to URL. When URL already contains fragment value, UrldatError will be thrown


String urldat(String base, String pathOrTemplate,
    {Map<String, dynamic>? parameters,
    String? scheme,
    int? port,
    String? fragment}) {
  final uri = Uri.parse(base);

  if (hasScheme(uri) && scheme != null) {
    throw UrldatError.basePathSchemeError();

  if (hasFragment(pathOrTemplate) && fragment != null) {
    throw UrldatError.pathFragmentError();

  final parsedScheme = scheme != null ? Uri(scheme: scheme).scheme : null;

  final sanitizedBase = removeTrailingSlash(base);
  final sanitizedPathWithoutSlash =
  final sanitizedPath = removeTrailingQuestionMark(sanitizedPathWithoutSlash);

  if (isTemplate(sanitizedPath)) {
    if (parameters == null) {
      throw UrldatError.missingParametersWithTemplateError();

    if (parameters.isEmpty) {
      throw UrldatError.emptyParametersWithTemplateError();

    final templateKeys = getTemplateKeys(sanitizedPath);
    final queryParameterKeys =
        getQueryParameterKeys(templateKeys, parameters.keys.toSet());

    final filledTemplate =
        fillTemplateWithValues(sanitizedPath, templateKeys, parameters);
    final queryParameters =
        createQueryParametersWithKeys(parameters, queryParameterKeys);

    return joinParts(
      base: sanitizedBase,
      path: filledTemplate,
      query: queryParameters,
      scheme: parsedScheme,
      port: port,
      fragment: fragment,

  final queryParameters = createQueryParameters(parameters);

  return joinParts(
    base: sanitizedBase,
    path: sanitizedPath,
    query: queryParameters,
    scheme: parsedScheme,
    port: port,
    fragment: fragment,