Dart HttpStatus

last modified April 4, 2025

The HttpStatus class in Dart provides constants for HTTP status codes. It's part of the dart:io library and essential for web development and HTTP communication.

HttpStatus contains numeric constants for all standard HTTP status codes. These codes indicate success, failure, or other conditions in HTTP responses.

Basic Definition

HttpStatus is a utility class containing static integer constants. Each constant represents a standard HTTP status code with a descriptive name.

The class covers all status codes from informational (1xx) to server errors (5xx). Using these constants improves code readability and maintainability.

Checking Success Status

This example demonstrates checking if an HTTP response indicates success.

import 'dart:io';

void main() {
  int statusCode = 200;
  
  if (statusCode >= HttpStatus.ok && 
      statusCode < HttpStatus.multipleChoices) {
    print('Request succeeded');
  } else {
    print('Request failed');
  }
  
  print('OK status code: ${HttpStatus.ok}');
}

We check if the status code falls in the success range (200-299). The HttpStatus.ok constant represents 200, the standard success code.

$ dart main.dart
Request succeeded
OK status code: 200

Handling Redirects

This example shows how to identify different types of redirect responses.

import 'dart:io';

void handleRedirect(int statusCode) {
  switch (statusCode) {
    case HttpStatus.movedPermanently:
      print('301 - Moved Permanently');
      break;
    case HttpStatus.found:
      print('302 - Found');
      break;
    case HttpStatus.seeOther:
      print('303 - See Other');
      break;
    case HttpStatus.temporaryRedirect:
      print('307 - Temporary Redirect');
      break;
    case HttpStatus.permanentRedirect:
      print('308 - Permanent Redirect');
      break;
    default:
      print('Not a redirect');
  }
}

void main() {
  handleRedirect(HttpStatus.movedPermanently);
  handleRedirect(HttpStatus.temporaryRedirect);
}

We use HttpStatus constants to identify specific redirect types. Each redirect has different implications for how clients should handle it.

$ dart main.dart
301 - Moved Permanently
307 - Temporary Redirect

Error Handling

This example demonstrates handling different HTTP error statuses.

import 'dart:io';

String getErrorMessage(int statusCode) {
  if (statusCode == HttpStatus.badRequest) {
    return '400 - Bad Request';
  } else if (statusCode == HttpStatus.unauthorized) {
    return '401 - Unauthorized';
  } else if (statusCode == HttpStatus.forbidden) {
    return '403 - Forbidden';
  } else if (statusCode == HttpStatus.notFound) {
    return '404 - Not Found';
  } else if (statusCode >= HttpStatus.internalServerError) {
    return '5xx - Server Error';
  } else {
    return 'Unknown error';
  }
}

void main() {
  print(getErrorMessage(HttpStatus.notFound));
  print(getErrorMessage(HttpStatus.internalServerError));
}

We use HttpStatus constants to identify specific client and server errors. The function returns appropriate error messages based on the status code.

$ dart main.dart
404 - Not Found
5xx - Server Error

Creating HTTP Responses

This example shows using HttpStatus when creating HTTP server responses.

import 'dart:io';

void handleRequest(HttpRequest request) {
  try {
    // Process request
    request.response.statusCode = HttpStatus.ok;
    request.response.write('Success');
  } catch (e) {
    request.response.statusCode = HttpStatus.internalServerError;
    request.response.write('Error: $e');
  } finally {
    request.response.close();
  }
}

void main() async {
  var server = await HttpServer.bind('localhost', 8080);
  print('Server running on port 8080');
  
  await for (var request in server) {
    handleRequest(request);
  }
}

We set appropriate status codes in HTTP responses using HttpStatus constants. This ensures standard compliance and better client handling of responses.

$ dart main.dart
Server running on port 8080

Validating Status Codes

This example demonstrates validating HTTP status code ranges.

import 'dart:io';

String getStatusCategory(int statusCode) {
  if (statusCode < HttpStatus.continue_ || statusCode > 599) {
    return 'Invalid status code';
  } else if (statusCode < HttpStatus.ok) {
    return 'Informational';
  } else if (statusCode < HttpStatus.multipleChoices) {
    return 'Success';
  } else if (statusCode < HttpStatus.badRequest) {
    return 'Redirection';
  } else if (statusCode < HttpStatus.internalServerError) {
    return 'Client Error';
  } else {
    return 'Server Error';
  }
}

void main() {
  print('200: ${getStatusCategory(200)}');
  print('404: ${getStatusCategory(404)}');
  print('500: ${getStatusCategory(500)}');
}

We categorize status codes into standard HTTP ranges using HttpStatus constants. The function helps understand the general meaning of any valid status code.

$ dart main.dart
200: Success
404: Client Error
500: Server Error

Best Practices

• Use constants: Always prefer HttpStatus over magic numbers
• Range checks: Validate codes against standard ranges
• Document: Include status code meanings in documentation
• Error handling: Provide appropriate responses for each code

Source

Dart HttpStatus Documentation

This tutorial covered Dart's HttpStatus class with practical examples showing status code handling, validation, and HTTP server response creation.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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