value method

@override String? value(String name)

Convenience method for the value for a single valued header.

The value must not have more than one value.

Returns null if there is no header with the provided name.

Implementation

@override
String? value(String name) {
  final lcName = name.toLowerCase();

  final values = _data[lcName];
  if (values != null) {
    if (values.isEmpty) {
      return null; // unexpected: treat as if header does not exist
    } else if (values.length == 1) {
      return values.first;
    } else {
      // Multiple values not permitted for this method.
      //
      // This is the exception that the implementation of
      // `_HttpHeaders.value`, in the Dart SDK internal "http_headers.dart"
      // file, throws when there are multiple values.
      throw HttpException('More than one value for header $name');
    }
  } else {
    return null; // header does not exist
  }
}